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JOURNAL OF THE AUDIO ENGINEERING SOCIETYAUDIO / ACOUSTICS / APPLICATIONSVolume 50 Number 7/8 2002 July/August

In this issue…

Amplifier OutputStages

Low-Frequency Sound Reproduction

Reconstructing Missing Audio

Standards:Call for Comment

Features…

113th ConventionLos Angeles—Preview

23rd Conference, Copenhagen—Call for Papers

Update: Sections Directory

The Audio Engineering Society recognizes with gratitude the financialsupport given by its sustaining members, which enables the work ofthe Society to be extended. Addresses and brief descriptions of thebusiness activities of the sustaining members appear in the Octoberissue of the Journal.

The Society invites applications for sustaining membership. Informa-tion may be obtained from the Chair, Sustaining Memberships Com-mittee, Audio Engineering Society, 60 East 42nd St., Room 2520,New York, New York 10165-2520, USA, tel: 212-661-8528. Fax: 212-682-0477.

ACO Pacific, Inc.Air Studios Ltd.AKG Acoustics GmbHAKM Semiconductor, Inc.Amber Technology LimitedAMS Neve plcATC Loudspeaker Technology Ltd.Audio LimitedAudiomatica S.r.l.Audio Media/IMAS Publishing Ltd.Audio Precision, Inc.AudioScience, Inc.Audio-Technica U.S., Inc.AudioTrack CorporationAutograph Sound Ltd.B & W Loudspeakers LimitedBMP RecordingBritish Broadcasting CorporationBSS Audio Cadac Electronics PLCCalrec AudioCanford Audio plcCEDAR Audio Ltd.Celestion International LimitedCentre for Signal ProcessingCerwin-Vega, IncorporatedCommunity Professional Loudspeakers, Inc.Cox Audio EngineeringCrystal Audio Products/Cirrus

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IndustryJBL ProfessionalJensen Transformers Inc.Kawamura Electrical LaboratoryKEF Audio (UK) LimitedKenwood U.S.A. CorporationKlark Teknik Group (UK) PlcKlipsch L.L.C.Laboratories for InformationLectret Precision Pte. Ltd.Leitch Technology CorporationLindos ElectronicsMagnetic Reference Laboratory (MRL) Inc.Martin Audio Ltd.Meridian Audio LimitedMetropolis Studios and MasteringMiddle Atlantic Products Inc.Mosses & MitchellM2 Gauss Corp.Music Plaza Pte. Ltd.National Semiconductor CorporationGeorg Neumann GmbH Neutrik AGNVisionNXT (New Transducers Ltd.)1 LimitedOntario Institute of Audio Recording TechnologyOutline sncPRIMEDIA Business Magazines & Media Inc.Prism Sound

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Systems EngineeringUniversity of SalfordUniversity of Surrey, Dept. of Sound

RecordingVidiPaxWenger CorporationJ. M. Woodgate and AssociatesYamaha Research and Development

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AES Journal of the Audio Engineering Society(ISSN 0004-7554), Volume 50, Number 7/8, 2002 July/AugustPublished monthly, except January/February and July/August when published bi-monthly, by the Audio Engineering Society, 60 East 42nd Street, New York, NewYork 10165-2520, USA, Telephone: +1 212 661 8528. Fax: +1 212 682 0477. E-mail: [email protected]. Periodical postage paid at New York, New York, and at anadditional mailing office. Postmaster: Send address corrections to Audio Engineer-ing Society, 60 East 42nd Street, New York, New York 10165-2520.

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AUDIO/ACOUSTICS/APPLICATIONS

VOLUME 50 NUMBER 7/8 2002 JULY/AUGUST

CONTENT

PAPERSOn the Design and Efficiency of Class A, B, AB, G, and H Audio Power Amplifier Output Stages................................................................................Rosalfonso Bortoni, Sidnei Noceti Filho, and Rui Seara 547Audio power amplifiers are usually analyzed with resistive loads with an added compensation factor for nominally reactive loads of real loudspeakers. The current study examines amplifiers of class A, B, AB, G,and H under conditions of reactive loads with sine wave to determine the true stress on the power stage. By using a more exact method, the economic inefficiency of the older approximation is avoided. A procedure for designing and assessing output stages is also proposed.

Requirements for Low-Frequency Sound Reproduction, Part I:The Audibility of Changes in Passband Amplitude Ripple and Lower System Cutoff Frequency and Slope .....................Søren Bech 564The low-frequency loudspeaker in a 5.1 system has been investigated in terms of perception of its frequency cutoff, slope of the cutoff, and passband ripple. The cutoff frequency has a very significant effect on the subjective sense of “lower bass,” but the cutoff slope was found not to be significant. The audibility of ripple depends on the nature of the audio signal. Results were consistent in both an anechoic test procedure and a headphone simulation of that environment.

ENGINEERING REPORTSRequirements for Low-Frequency Sound Reproduction, Part II: Generation of Stimuli and Listening System Equalization.....................................................Jan Abildgaard Pedersen and Aki Mäkivirta 581Using headphones to simulate the perception of loudspeakers in an anechoic chamber is easier and more efficient, but it requires signal processing to produce the equivalent sound signals. This study describes the algorithms used in a previous study of the low-frequency channel loudspeaker. Signals were pre-equalized with added nonlinear processing based on head-related transfer measurements made in an anechoic chamber with an actual loudspeaker.

Reconstruction Method for Missing or Damaged Long Portions in Audio Signal.......................................................................................................Ismo Kauppinen and Jyrki Kauppinen 594Using a reconstruction method described previously, the authors demonstrate an algorithm that replaces gaps of up to several thousand samples with synthesized audio. Using three different types of music, the extrapolation method was able to reconstruct successfully the missing audio, so that listeners could not hear the difference between it and the original. The method was applied in practice to correct scratches from badly damaged recordings, but it can also work with any kind of impulse noise in real time.

STANDARDS AND INFORMATION DOCUMENTSAES Standards Committee News........................................................................................................... 603Acoustics and sound-source modelingCall for Comment on REVISION of AES10-1991(r1997), AES recommended practice for digital audio engineering—Format for the user data channel of the AES digital audio interface................................ 603

FEATURES113th Convention Preview, Los Angeles ............................................................................................... 606

Calendar ................................................................................................................................................. 608Exhibitors............................................................................................................................................... 610Exhibit Previews.................................................................................................................................... 614

Updates and Corrections to the 2001/2002 International Sections Directory.................................... 63623rd Conference, Copenhagen, Call for Papers.................................................................................... 641

DEPARTMENTS News of the Sections ........................................629Upcoming Meetings ..........................................634Sound Track........................................................635Advertiser Internet Directory............................635

Membership Information...................................637In Memoriam ......................................................639Sections Contacts Directory ............................642AES Conventions and Conferences ................648

PAPERS

INTRODUCTION

With the advent of the electronic tube in 1906, musiccould be transmitted for the first time through radio fre-quencies in 1907. After 1915 the first amplification systemsof voice and music for the public have appeared [1]. Eversince, the need for obtaining more and more powerful voiceand music reproduction systems has led to studies of newvoicing techniques and the conception of new audio ampli-fier structures. Because of several enclosure types [2], con-sidering their low efficiencies [3] and the large requiredelectric power levels, the efficiency parameter is, amongothers, one of the main requirements for a power amplifier.Thus diverse operation classes have been proposed. Bothoperation points and operation modes characterize theoperation classes in a power amplifier output stage.

In this paper classes A, B, AB, G, and H are considered,analyzed, and treated under the same considerations ofoperation, using both resistive and reactive loads (the lat-ter representing the usual loudspeakers and enclosurestructures). In this case electrical–mechanical–acousticalmodels [3] are used. In the literature other classes of oper-ation (C, D, E, F, I, and S) [4] – [7] are found. The aim ofthis paper is to provide a parameter analysis of the outputstage with regard to the currents and voltages of the out-put stage as well as its power and thermal performance

under several situations and conditions of operation. Allthose parameters are obtained taking into account sinu-soidal signals for BJT, IGBT, and MOSFET technologies.Until now almost all the studies for these amplifyingstructures have been oriented toward distinct operationclasses under specified conditions. To have a more exten-sive view of the state-of-the-art in audio power amplifiers,let us give a brief bibliographic review of these structures.

Class A amplifiers have less efficiency; however, theyalso present a lower harmonic distortion level. They areonly discussed for the purpose of comparison [1], [5] –[8]. In general most of the analyses are developed takinginto account resistive loads only [5] – [14]. For reactiveloads the analyses are mostly restricted to class B (or classAB, considering low bias current) [15] – [18]. This is dueto the fact that this amplifier class presents a simpler math-ematical formulation. (In this case, loads with constantimpedance magnitude and variable phase are used.) Insome cases commercial acoustical enclosure models arealso considered [19] – [21]. Classes G and H operate withdifferent power supply voltages at the audio power ampli-fier stage. They have only been described and analyzed fortwo stages [9] – [12], [22], [23]. In the literature, no math-ematical formulations for classes G and H with more thantwo stages are found. Some allusions are slight made tothree or four stages [1], [9], [24]. Moreover, all the analy-ses are accomplished for distinct transistor technologies(BJT or MOSFET), and the design is approached superfi-cially [24].

In the face of little or insufficient information and the

J. Audio Eng. Soc., Vol. 50, No. 7/8, 2002 July/August 547

On the Design and Efficiency of Class A, B, AB, G, andH Audio Power Amplifier Output Stages*

ROSALFONSO BORTONI, AES Associate Member, SIDNEI NOCETI FILHO, AND RUI SEARA

Circuits and Signal Processing Laboratory, Department of Electrical Engineering,Federal University of Santa Catarina, 88040-900 Florianópolis-SC, Brazil

A procedure for analyzing, designing, and assessing audio power amplifier output stagesoperating in classes A, B, AB, G, and H with reactive loads is presented. The study considerssteady-state sinusoidal analysis for BJT, IGBT, and MOSFET technologies. Electrical–mechanical–acoustical models of loudspeakers and enclosures are used whose parametersare obtained through the Thiele–Small model. An equivalent electrical–thermal model for atransistor–heatsink–ambience system associated with instantaneous and average powers isused for designing the power stage. A MATLAB software has been developed, which providesconsiderable support to the designer for all phases required in the design of audio poweramplifier output stages.

* Presented at the 110th Convention of the Audio EngineeringSociety, Amsterdam, The Netherlands, 2001 May 12 – 15;revised 2002 May 14.

BORTONI ET AL. PAPERS

lack of a unified mathematical treatment for audio poweramplifier output stages found in the literature, we proposethe following topics for this work:

1) A unified analysis for classes A, B, AB, G, and H,using both resistive and reactive loads

2) A generic expression for classes G and H with mul-tiple stages

3) A generic expression of the amplifier efficiency forclasses A, B, AB, G, and H

4) A mathematical formulation for the different opera-tion classes taking into account BJT, IGBT, and MOSFETtechnologies

5) A design methodology for the power stages withreactive loads considering an equivalent electrical–ther-mal model taking into account the instantaneous and aver-age powers

6) A computer-aided analysis and design based onMATLAB software.

1 RESISTIVE LOAD

1.1 Classes A, B, and ABFig. 1 shows the diagram of an output stage (comple-

mentary stage), which is the basic cell of class A, B, andAB amplifiers. For these classes the total average powersupplied by two sources, VCC1 and VCC2, is PS PS PS 2VCC IC since the average power provided by thepower supplies is identical, equal to PS and PS. Forclass A, IC ∫ IQ is the quiescent current of transistor Q1.For class B, IC ∫ IS is the average current in Q1, which ispresent only in a half-cycle of each signal period, and forclass AB, IC ∫ IS (qQ) is the average current, which is afunction of both the bias current IQ and the load current iL(see Fig. 3). For the three classes VCC VL max VCE sat.

Fig. 2 shows the collector and load currents for a classA output stage. In this figure Iman is defined as mainte-nance current, which is the current needed to ensure thetransistor operation in the active region for the extremeconditions of signal amplitude. In that case,

.II

I2

maxQ

Lman (1)

Then,

.P V VI

I22

maxmax

S L CE satL

man_ ei o (2)

The average power PL delivered to the load is given byPL V 2

L/2RL, where VL is the peak voltage at the load. Bydefining the factor g as g Iman/IL max and considering thatIL max VL max/RL, we obtain the efficiency factor h PL/PS, given by

/.h

gV

V

V V2

1

1

1

1 2

1

max maxL

L

CE sat L

2J

L

KK

N

P

OO (3)

Eq. (3) denotes that the maximum theoretical efficiencyfactor for class A operation is 50%, considering VCE sat 0, Iman 0, and VL VL max. This equation is also validfor IGBT devices. It can be shown that in the case ofMOSFET devices, the ratio VCE sat/VL max in Eq. (3) is

given by RDS on/RL, where RDS on is the conduction resist-ance between drain and source of the MOSFET [14].Thus,

/.h

gV

V

R R2

1

1

1

1 2

1

maxL

L

DS on L

2J

L

KK

N

P

OO (4)

In the class B case one should consider VBIAS 0. AsIS IL/p and IL VL/RL, one can show that

.p

P VV

V I2 1 max

maxS L

L

CE sat LJ

L

KK

N

P

OO (5)

Now considering that h PL/PS, we have

/.h

pV

V

V V4 1

1

max maxL

L

CE sat L(6)

Eq. (6) denotes that the maximum theoretical efficiencyfactor for class B operation is 78.5%, considering VCE sat 0 and VL VL max. Similarly we obtain for MOSFETdevices

/.h

pV

V

R R4 1

1

maxL

L

DS on L(7)

In the class AB case we should consider VBIAS > 0, but lessthan the voltage needed for class A operation (Fig. 1). Fig.

548 J. Audio Eng. Soc., Vol. 50, No. 7/8, 2002 July/August

Fig. 2. Transistor collector currents (Q1 and Q2) and load current.

Fig. 1. Output stage of class A, B, and AB amplifiers.

PAPERS AUDIO POWER AMPLIFIER OUTPUT STAGES

3 depicts the bias current IQ, load current iL, and collectorcurrents iC1 and iC2 as a function of the angle q. Based onthis figure, we can show that the average current IS(qQ) isgiven by

cosq qp p

qI II2

S Q Q QL

Qr ` j (8)

where IQ < IL max/2, and qQ is the transition anglebetween class A and class AB operation. That angle canbe represented as a function of the design parameters asfollows. Based on Fig. 3, we can obtain IQ (IL max/2)sin qQ or, alternatively, qQ sin1(2IQ/IL max), and byusing Eq. (8), we determine an expression for IS(qQ) asa function of qQ and IL,

.sin cosqp

q qp

qII I

maxS Q

LQ Q

LQ

r ` j (9)

For qQ 0 and IS(qQ) IL/p, we operate in class B. ForqQ p/2 and IS(qQ) IL max/2, we have class A (withIman 0). For 0 < qQ < p/2, we obtain class AB bias [8].Thus we can show that

sin cosp

q q qPR

V

V

VV V

21 max

maxmaxS

L

L

L

CE satL Q Q L Q

J

L

KK `

N

P

OO j

(10)and the efficiency factor, h PL/PS,

For MOSFET devices,

Fig. 4 shows the efficiency factor as a function of the out-put power for VCE sat 0. It is parameterized by the factorl, which is defined as l 2IQ/IL max. In this way the tran-sition between class B (IQ 0) and class A (IQ IL max/2),for Iman 0, is obtained.

1.2 Classes G and H with Multiple StagesThe definitions adopted in this paper for classes G and H

are according to those found in the references [1], [12],[22] – [24]. Fig. 5 shows the basic output structures of audiopower amplifiers, class G [Fig. 5(a)] and class H [Fig. 5(b)and (c)] [1], [23], [24], for multiple stages. In these struc-tures the output stages can be biased toward classes A, B, orAB. In this work we first consider class B bias; next, con-siderations are given to obtaining class A and class AB bias.

Analyzing the circuit in Fig. 5(a), disregarding the diodelosses, we can write

P V I V I V I2 2 2 S CC S CC S CC SN N1 1 2 2 gr r r (13)

where ISi, for i 1, . . . , N, are the average currents pro-vided by the power supplies VCCi. In Fig. 6, qTi, for i 1,. . . , N, represents the transition angle, corresponding tothe operation switching of the ith stage, and

, , , .aV V iV i N1 maxCC L CE sati i f (14)

Substituting Eq. (14) into Eq. (13), we obtain

.aP V iV I2 maxS L CE sat Si ii

N

1

! r_ i8 B (15)


Fig. 3. Transistor collector currents and load current. Fig. 4. Efficiency factors for class AB amplifiers.

/ /

/.

sin cosh

pq q qV

V

V V V V

V V

4 1

1

max max max

max

L

L

CE sat L Q Q L L Q

L L

_ i

(11)

/ /

/.

sin cosh

pq q qV

V

R R V V

V V

4 1

1

max max

max

L

L

DS on L Q Q L L Q

L L

_ i

(12)



Fig. 6. Transition angle.

Fig. 5. Output structures of multiple-stage amplifiers. (a) Class G. (b), (c) Class H.

(c)

(a) (b)


By isolating ai in Eq. (14) and considering that aN 1,we have

aV NV

V iV

CC CE sat

CC CE sati

N

i (16)

<

, ,

sinq

a a

aa

aV

VV

V

i N

0

1

1

( )max

max

TL

LL

L

i i

i i

N

11

1

1

0

f

#J

L

KK

N

P

OO

Z

[

\

]]]

]]]

(17)q q

pand0

2 T TN0

Current ISi is given by

, , , .sinp

q qdII

i N1

q

q

SL

i

( )

( )

T

T

i

i

1

f#r (18)

Solving Eq. (18) and substituting into Eq. (15) results in

pP

R

VA

2S

L

Li

i

N

1

! (19)

where Ai (ai ai1 VL max/VCE sat) cos qT(i1). Substituting Eq. (19) into h PL/PS, we obtain the effi-

ciency factor for a class G amplifier with N stages,

.hp

V

V

A4

1

maxL

L

ii

N

1!(20)

For MOSFET devices the efficiency factor is given by

hp

V

V

B4

1

maxL

L

ii

N

1!(21)

where Bi (ai ai1 RDS on/RL) cos qT(i1).Analyzing the circuits shown in Fig. 5(b) and (c), disre-

garding the diode and switch losses, we can write

P V I V I V I2 2 2 S CC S CC S CC SN N1 1 2 2 gr r r (22)

and

.aV V V maxCC L CE sati i (23)

By substituting Eq. (23) into Eq. (22) we obtain

.aP V V I2 maxS L CE sat Si ii

N

1

! r_ i8 B (24)

Comparing Eqs. (24) and (15) we notice that the differ-ence between them is the factor i, which is multiplyingVCE sat. That factor does not appear in Eq. (24) because thetransistors are arranged in a different configuration.

Considering the same design parameters mentioned previ-ously, we can write the following expressions for the efficiencyfactor of this amplifier stage, using BJT or IGBT devices,

/h

p

CV

V

V V4

1

maxmax

L

L

CE sat L ii

N

1!(25)

where Ci (ai ai1) cos qT(i1). For MOSFET devices,

/.h

p

CV

V

R R4

1

maxL

L

DS on L ii

N

1!(26)

For VCE sat 0 and RDS on 0, Eqs. (25) and (26) becomeidentical to Eqs. (20) and (21), respectively. Fig. 7 pres-ents, respectively, the efficiency factors and the dissipatedaverage powers (see Section 2.3) of classes G and H fordifferent values of N with ai i/N and class B bias at theoutput stage.

Let us now consider a practical case for which VCE sat ≠0. Fig. 8 presents the efficiency factors for classes Gand H with VCE sat/VL max 0.025 and N 4; and withVCE sat/VL max 0.015 and N 6.

1.3 Comparison of Efficiency FactorsFig. 9 shows a comparison between the efficiency fac-

tors of the diverse operation classes studied. For that com-parison the following parameter values were adopted:VCE sat/VL max 0.003 (all classes), g 0.10 (class A),l 0.02 (class AB), and a1 0.55 [classes G and H withtwo stages (N 2) and class B bias]. The smaller effi-


Fig. 7. Classes G and H for multiple stages, with VCE sat 0 and class B bias. (a) Efficiency factors. (b) Dissipated average powers.

(a) (b)


ciency factors were obtained for the class A configurationwith a maximum efficiency of 40.6%. The larger effi-ciency factors were obtained for class H, whose maximumvalue is 82.2%. The maximum efficiencies obtained forclasses B and AB are approximately 76.2% and 76.1%,respectively. The slight difference observed between thecurves is attributed to the small bias current used in theclass AB stage. As expected, the class G and H efficiencyfactors are identical up to the transition point. From thatpoint forward, a deviation occurs due to the particulartopologies used. The maximum efficiency factor for theclass G configuration is 80.1%. It is important to note thatthe greatest advantage of classes G and H, mainly in con-sumer applications, is the large increase in efficiency atmedium power. In this case, when comparing classes Gand H with class B (Fig. 9), at one-third power the effi-ciency ratio is approximately 1.8, compared to 1.08 at fullpower.

1.4 General Representation for EfficiencyFactors

A unified expression to represent the efficiency factorsfor classes A, B, AB, G, and H is obtained. ComparingEqs. (3), (6), (11), (20), and (25) we can write

hp

q gV

VX Y N Z

4

maxL

LQ` _ _j i i (27)

where

/

/

sin cosq

q q qX

V V

V V

max

maxQ

Q Q L L Q

L L`

_

j

i

(28)

gg

Z1 2

1

_ i (30)

Term X(qQ) determines the operation class as a function ofthe bias for classes A, B, and AB. Term Y(N) establishes theoperation class as a function of the operation mode for

classes G (k 1) and H (k 0). Term Z(g) is a function ofg for the bias of class A and equal to 1 for the other classes.

From Eq. (27) we directly obtain classes G and H, withclass A (qQ p/2 and g ≥ 0) or class AB (0 < qQ < p/2)biases. Eqs. (27), (28), and (30) are valid for BJT, IGBT, andMOSFET devices, whereas Eq. (29) is only valid for BJT andIGBT devices. When the term VCE sat/VL max is substitutedwith RDS on/RL, Eq. (29) is also valid for MOSFET devices.

2 REACTIVE LOAD

2.1 Average PowerIn a practical case, contrary to what is considered in

most studies, the audio-frequency amplifiers are loadedwith loudspeakers of one or more frequency ways (withpassive crossovers). Loudspeakers (with or without enclo-sures) present complex impedances [3], which are fre-quency dependent.

In this way, the average power delivered to the load is

cosww

j wPZ

V

2L

L

L2

_

_

_i

i

i (31)

where |ZL(w)| and j(w) are the magnitude and phase,respectively, of the load impedance. Let us examine theexample of Fig. 10 (Appendix 2). In the analysis that fol-lows the effect of ZL(w) on the behavior of the operationclasses mentioned is studied. Thus,

wI

Z

VL

L

L

_ i

(32)

wI

Z

Vmax

min

maxL

L

L

_ i

(33)


Fig. 8. Efficiency factor examples of classes G and H. (a) N 4. (b) N 6.

cosa a q

Y N

kV

Vk

V

V1

1

max maxL

CE sat

L

CE satTi i i

i

N

1 1

1

!J

L

KK

_

_ _

N

P

OO

i

i i

R

T

SSS

V

X

WWW

(29)

(a) (b)


where IL is the peak current of the load, and VL max andIL max correspond to the maximum values of VL and IL,respectively. Fig. 11 shows a graph of the power in a reac-tive load, whose impedance is depicted in Fig. 10, consid-ering that the amplifier is capable of delivering 100 W toa nominal load of 8 W.

2.2 Efficiency FactorNow let us redo the analyses described in Section 1.

Considering Eqs. (31), (32), and (33), we obtain anexpression for the efficiency factor h(w) (consideringreactive loads) for classes A, B, AB, G, and H, using BJTand IGBT devices. (For MOSFET devices it is enough toexchange VCE sat/VL max for RDS on/|ZL(w)|min),

cosh wp

q g w j wV

VX Y N Z R

4

maxL

LQ_ ` _ _ _ _i j i i i

(34)

where

.ww

wR

Z

Z min

L

L_

_

_

i

i

i

(35)

The term R(w) for class A bias is a function of ZL(w); forthe other classes R(w) is equal to 1. The other terms are thesame as defined in Section 1.4.

2.3 Dissipated Average PowerThe dissipated average power PD(w) can be determined

through the average power in the load PL(w) and the effi-ciency factor h(w) by the following expression:

.w wh w

P P1

1 D L

J

L

KKK

_ _

_

N

P

OOO

i i

i

(36)

By combining the efficiency factor expression in Eq. (34)with Eq. (31) we obtain the dissipated average power foreach class in question.

2.4 Dissipated Instantaneous PowerThe dissipated instantaneous power Pd(t) in each arm of

a push–pull stage can be determined by the productbetween instantaneous current i(t) and instantaneous volt-age v(t), both for the same arm. Thus,

P t i t v td _ _ _i i i (37)

where

,

, <

wi ti t

Z

VD i t

i t0

0

0

max

L

L $l l

l

_

_

_

_

_

i

i

i

i

i

Z

[

\

]]

]]

(38)

for the operation in classes A, B, AB, G, and H, with D


Fig. 9. Comparison of efficiency factors for class A, B, AB, G,and H operations.

Fig. 10. Sixth-order band-pass loudspeaker, magnitude and phase.


(qQ/p) sin qQ (1 2ag sin wt) sin wt • cos qQ, a 1 forclass A and a 0 for classes B and AB, and

sin w j wav t V bV

Vt max

maxL

L

CE sati_ _i i8 B* 4

(39)

where b 1 and ai 1 for classes A, B, and AB; b 1and ai a1 for sin[wt j(w)] ≤ 0, and b i for ai1 <sin[wt j(w)] ≤ ai for class G; b 1 for ai1 < |sin[wt j(w)]| ≤ ai for class H [Fig. 5(b)]; and b 1 and ai a1for sin[wt j(w)] ≤ 0, and b 1 for ai1 < sin[wt j(w)] ≤ ai for class H [Fig. 5(c)]; for i 1, . . . , N.

3 AMPLIFIER DESIGN

In order to obtain an adequate operation, the transistorsshould operate within the imposed limitations given bytheir manufacturers (obtained from the product datasheet). In [25] – [27] a design procedure is presented anddiscussed which uses the thermal behavior of the transis-tor junctions by assuming that the dissipated power signalwaveform is a pulse train, which simulates the steady-stateswitching. However, the effort of the output stage is afunction of the operation class (which here does not oper-ate in the switching regime), bias, losses, and load type(frequency function). Therefore such a design proceduredoes not take into account all the main points involved inthe problem as such.

Thus in the same way as in [24] we have used as amodel of the thermal effect the filtering of the dissipatedinstantaneous power signal Pd(t) by a linear invariant sys-tem (thermal equivalent), representing the transistor–heatsink–ambience system. In this way one can obtain thejunction average and instantaneous temperatures, TJ andTJ (t), of the transistors involved in the process.

3.1 Transistor LimitationsThe transistor limitations are given by the safe operat-

ing area (SOA), which is provided by the transistor man-

ufacturer, where the current IC MAX or ID MAX, voltageVCE MAX or VD MAX, and power PD MAX limitations aregiven for a given ambient TA or case TC temperature [28],[29]. Then,

(40)

(41)

<

<

<

<

<

or

or

i t I I

v t V V

P P

T T

T t T

max

max

max

max

max

C MAX D MAX

CE MAX DS MAX

D D MAX

J J MAX

J J pk

_

_

_

i

i

i

(42)

(43)

(44)

where PD max is the maximum dissipated average power,TJ max and TJ(t)max are the average and instantaneous max-imum junction temperatures, and TJ MAX and TJ pk are theaverage and peak admissible maximum junction tempera-tures (given by the manufacturer).

3.2 Equivalent Electrical–Thermal CircuitA simplified equivalent electrical–thermal circuit for a

transistor–heatsink–ambience system is shown in Fig. 12[30]. That configuration enables us to obtain the requiredtemperatures for this application: average TJ and instanta-neous TJ(t) junction temperatures; case TC and ambient TAtemperatures, which is the former TJ, the only one that isnot directly measured.

The circuit depicted in Fig. 12 is common to BJT,IGBT, and MOSFET devices. To obtain the average tem-perature (dc temperature), the reactances due to the ther-mal capacitances are considered infinite, taking intoaccount only the thermal resistances. Thus,

T P R R R T J D JC CD DA A_ i (45)

or even

.T P R T J D JC C (46)

These are the expressions to obtain TJ in steady-state oper-ation using the design data (PD, RJC, RCD, RDA, TC, and TA,


Fig. 11. Amplifier power response for reactive load of Fig. 10.


where RJC, RCD, and RDA are the thermal resistancesbetween junction and case, case and heatsink, andheatsink and ambience, respectively).

3.3 Transistor AssociationFig. 13 shows the circuit of Fig. 12 adapted for the case

of NT transistors, for which we can write

(47)P t

N

P t

R R N

CN

C

2

dT

d

DA DA T

DT

D

__

ii

(48)

(49)

where Pd(t) is the dissipated instantaneous power in each

transistor, RDA and C

DA are the thermal resistance andthermal capacitance, respectively, of the heatsink seen foreach transistor, and NT is the number of associated tran-sistors.

Here matched transistors have been considered and theassociation is made allowing for a uniform power distri-bution. In practice, two procedures are used for accom-plishing the match between the transistors. The first is theprevious selection of the transistors (match of parameters)and the second is the introduction of a small negative feed-back in the circuit (resistances of emitter or source).

3.4 Instantaneous Junction TemperatureThe instantaneous junction temperature TJ(t) is deter-

mined through convolution between dissipated instanta-neous power Pd

(t) and system impulse response ZT(t).Therefore,

T t P t Z tJ d T*_ _ _i i i (50)

where ZT(t) is the impulse response of the system ZT(s)(Fig. 13 and Appendix 1), which is obtained by the inverseLaplace transform of ZT(s) [31].

By assigning values to the circuit components of Fig. 13(RJC RCD R

DA 1°C/W, CJ 0.01 J/°C, CC 1J/°C, C

D 100 J/°C, TA 2°C, TJ max 3°C), we findTJ(t) @ PD(RJC RCD R

DA) TA TJ (Fig. 14), whereTJ(t) is the average value of TJ(t), which is equal to TJ fort Æ ∞ [32].

Therefore, by calculating TJ0(t) [TJ(t) for TA 0°C] for

the first period of Pd(t) and superimposing TJ0(t) on TJ,

which is obtained by Eq. (45), one can determine the valueof TJ(t) for t Æ ∞ (Fig. 15), since in practice CJ << CC <<CD. Thus,

(51)

d

T t T t T t T

T tT

T t t1

J J J J

J J

T

0 0

0 0

t "3

#

r

r

_ _ _

_ _

i i i

i i(52)

where TJ(t)|t Æ ∞ is the instantaneous junction temperaturefor t Æ ∞ , TJ0(t) is the instantaneous junction temperaturefor the first cycle of Pd

(t), TA 0°C, and T is the periodof Pd

(t).

4 GENERAL ASSESSMENT

The aim of this section is to carry out a comparisonbetween the efforts of an output stage considering bothresistive load (conventional method) and reactive load(method proposed in this work). Let us design an outputstage, operating in class B at an output power of 100 W ona resistive load of 8 W. In the following we determine thepower, efficiency factor, voltages, currents, and evolvedtemperatures, considering the reactive load shown in Fig.10 (Appendix 2) (which theoretically should have a nom-inal impedance of 8 W). For comparison, the same hasbeen made for an output stage operating in class H [Fig.5(c)] with four stages and ai equal to those of Fig. 8(a).The design data are PL 100 W, RL 8 W, VCE sat 3 V,IC MAX 10 A, VCE MAX 140 V, PD MAX 125 W,RJC 1°C/W, RCD 0.7°C/W, R

DA 0.2°C/W, CJ 0.01 J/°C, CC 1 J/°C, C

D 100 J/°C, TJ max TJ pk 150°C, and TA 40°C.

Based on these data, and respecting all the criteriaestablished in Section 3, a pair of transistors (push–pullconfiguration) has been used, resulting in NT 2. Table 1presents the results of the efforts in the output stages forclasses B and H for both resistive and reactive loads.

In practice the design of a power stage is usually carriedout by considering only a resistive load. It is then assigneda safety limit and the circuit is tested. In this way there isno guarantee that the power stage is designed properly,which may render the design either technically or com-mercially unfeasible.

Figs. 16 – 22 synthesize what was presented and dis-


Fig. 12. Electrical–thermal equivalent circuit.Fig. 13. Thermal–electrical circuit for transistor associated withNT transistors.


cussed in this paper. Parts (a) illustrate the class B casewith resistive load, and parts (b) and (c) depict classes Band H with reactive load. Note that even with midrange

values (resistive load), the effort of the power stage is verysignificant for frequencies below 20 Hz. For instantaneousvalues (resistive and reactive loads) this effort is even


Fig. 14. Last cycle of TJ(t) for 1200 s of simulation.

Fig. 15. TJ(t) obtained using Eq. (51).

Table 1. Comparison of resistive and reactive loads.

Class B Class B Class HResistive Reactive Reactive

NT 2 2 2PD(w)max 46.8 W 56.1 W 39.5 WPL(w)max 100 W 108 W 108 Wh%(w)max 73.06% 73.06% 84.11%iC(t)max 5.0 A 5.4 A 5.4 AvCE(t)max 83.0 V 83.0 V 63.0 VPd

(t)max 57.8 W 126.6 W 70.2 WTJ max 84.5°C 93.3°C 77.5°CTJ0(t)max 31.9°C 66.4°C 35.9°CTJ(t)max 104.3°C 142.2°C 104.4°CTC max 61.1°C 65.2°C 57.8°CVCC1 –– –– 23.0 VVCC2 –– –– 31.3 VVCC3 –– –– 37.6 VVCC4 43.0 V 43.0 V 43.0 V


more expressive. By ensuring that there is no signal witha frequency below 20 Hz (practically inaudible), oneobtains a good design, maintaining the quality of theresults.

Another important point that must be considered are theexisting minima of the magnitude of the reactive loadimpedance, which reach smaller values than the nominalimpedance of the loudspeaker (8 W). Through graphicanalyses these minima are easily detected. Moreover, theactual loads (loudspeakers–passive crossover–enclo-

sures) can be assessed (by simulation) before they areeffectively used. In addition, in the case of passivecrossovers associated with loudspeakers, we can havehigh-order systems, such as 16th order or higher.

We can conclude that a proper design is performed if onetakes into account the reactive loads. Furthermore, the morecareful the design (specific loads), the better the output stageperformance will be. In general cases (general-purposeamplifiers) we should assess a larger number of possibleload configurations in order to obtain an adequate result.


Fig. 16. Dissipated average power. (a) Class B considering resis-tive load. (b) Class B considering reactive load. (c) Class H con-sidering reactive load.

Fig. 17. Efficiency factor. (a) Class B considering resistive load.(b) Class B considering reactive load. (c) Class H consideringreactive load.

(c) (c)

(b)(b)

(a)(a)


5 DISCUSSIONS AND CONCLUSIONS

Audio amplifiers are devices used in many differenttypes of applications. Therefore to design them is a diffi-cult task due to the numerous variables involved. Some ofthose variables are environmental factors (humidity, tem-perature, and so on), application types (fixed or mobileinstallations), transistor types (different properties, toler-ance in the electrical characteristics, and so on), and,mainly, the structures of the loudspeakers used.

In this work a design procedure has been proposed foraudio power amplifier output stages operating in classesA, B, AB, G, and H with reactive loads. Moreover, thedesign procedure also considers bias type, operationmode, and device technology (BJT, IGBT, and MOSFET).Analytical expressions are also obtained to determine effi-ciency factors for classes G and H, taking into account anarbitrary number of stages. The importance of consideringreactive loads instead of just resistive loads has been veri-fied. This is caused by the fact that the dissipated average


Fig. 18. Load lines. (a) Class B considering resistive load.(b) Class B considering reactive load. (c) Class H consideringreactive load.

Fig. 19. Dissipated instantaneous power. (a) Class B consideringresistive load. (b) Class B considering reactive load. (c) Class Hconsidering reactive load.

(c) (c)

(b) (b)

(a) (a)


power for reactive loads (real case) can reach larger valuesthan the one for resistive loads. If a smaller than requiredpower value were considered in the design, the outputstage would be underdimensioned, leading transistor junc-tion temperatures to overshoot the admissible maximumvalues. Until now the usual procedure has been to considerresistive loads, taking into account a certain tolerance.However, the use of such a tolerance does not ensure areliable design. Moreover, this procedure can render the

power amplifier design technically or commerciallyunfeasible. The results obtained in this paper lead to anadequate power stage design from both technical and eco-nomic points of view.

6 ACKNOWLEDGMENT

The authors wish to thank the anonymous reviewers fortheir useful comments and suggestions.


Fig. 20. Instantaneous junction temperature. (a) Class B consid-ering resistive load. (b) Class B considering reactive load.(c) Class H considering reactive load.

Fig. 21. Average junction temperature. (a) Class B consideringresistive load. (b) Class B considering reactive load. (c) Class Hconsidering reactive load.

(c) (c)

(b) (b)

(a) (a)


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Fig. 22. Maximum junction temperature. (a) Class B considering resistive load. (b) Class B considering reactive load. (c) Class H con-sidering reactive load.

(c)

(a) (b)


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[19] E. Benjamin, “Audio Power Amplifiers for Loud-speaker Loads,” J. Audio Eng. Soc., vol. 42, pp. 670 –683(1994 Sept.).

[20] M. Otala and P. Huttunen, “Peak Current Require-ment of Commercial Loudspeaker Systems,” J. AudioEng. Soc., vol. 35, pp. 455 – 462 (1987 June).

[21] I. Martikainen and A. Varla, “About LoudspeakerSystem Impedance under Transient Drive Conditions,”presented at the 71st Convention of the Audio EngineeringSociety, J. Audio Eng. Soc. (Abstracts), vol. 30, p. 357(1982 May), preprint 1886.

[22] L. Feldman, “Class G High Efficiency Hi-FiAmplifier,” Radio Electron., pp. 47 – 49, 87 (1976 Aug.).

[23] L. Feldman, “Class H Variproportional Amplifier,”Radio Electron., pp. 53 – 55, 106 (1977 Oct.).

[24] E. Mendenhall, “Computer-Aided Design andAnalysis of Class-B and Class-H Power Amplifier OutputStages,” presented at the 101st Convention of the AudioEngineering Society, J. Audio Eng. Soc. (Abstracts), vol.44, p. 1155 (1996 Dec.), preprint 4329.

[25] K. Gauen, “Designing with TMOS PowerMOSFETs,” Motorola, AN-913 (1993 Sept.).

[26] R. Locher, “Introduction to Power MOSFETs and TheirApplications,” National Semiconductors, AN-558 (1988 Dec.).

[27] B. Trump, “Power Amplifier Stress and PowerHandling Limitations,” Burr-Brown, AB-039 (1993).

[28] Motorola, “Bipolar Power Transistor Data,” DL111/D,ver. 7 (1995).

[29] Motorola, “TMOS Power MOSFET Transistor DeviceData,” DL135/D, ver. 6 (1996).

[30] D. Self, Audio Power Amplifier Design Handbook(Newnes, 1996).

[31] A. V. Oppenheim, A. S. Willsky, and S. H. Nawab,Signals and Systems, 2nd ed. (Prentice-Hall, EnglewoodCliffs, NJ, 1996).

[32] R. Bortoni, “Analysis, Design and Assessment ofClass A, B, AB, G and H Audio Power Amplifier OutputStages” (in Portuguese), MSEE dissertation, Federal Uni-versity of Santa Catarina, Santa Catarina, Brazil (1999 Apr.).

APPENDIX 1

The impedance ZT(s) seen by Pd(t) is given by (see Fig.

13)

Z ss Ds Es F

As Bs C

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where

AC

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APPENDIX 2

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Fig. 23. Electrical equivalent circuit of sixth-order band-pass system.

THE AUTHORS

R. Bortoni S. N. Filho R. Seara

Rosalfonso Bortoni was born in São Lourenço, MG,Brazil. He received a B.E. degree in electrical engineer-ing from the National Institute of Telecommunication(INATEL), Santa Rita do Sapucaí, MG, Brazil, in 1993.In 1999 he received an M.Sc. degree in electrical engi-neering from the Federal University of Santa Catarina(UFSC), Florianópolis, SC, Brazil, and he is currentlypursuing a doctoral degree in electrical engineering atUFSC. His research interests include signal processingand circuit analysis and design.

He is currently secretary of the Audio EngineeringSociety, Brazil Section.

Sidnei Noceti Filho was born in Florianópolis, SC,Brazil. He received B.E. and M.Sc. degrees in electricalengineering from the Federal University of Santa Catarina(UFSC), Florianópolis, SC, Brazil, in 1975 and 1980,respectively. In 1985 he received a doctoral degree inelectrical engineering from the Federal University of Riode Janeiro (COPPE/UFRJ), RJ, Brazil. In 1976 he joinedthe Electrical Engineering Department of UFSC, wherehe has been engaged in education and research in signalprocessing and circuit analysis and design. He has beenprofessor of electrical engineering at UFSC since 1993December.



Rui Seara was born in Florianópolis, SC, Brazil. Hereceived B.E. and M.Sc. degrees in electrical engineer-ing from the Federal University of Santa Catarina,Florianópolis, SC, Brazil, in 1975 and 1980, respec-tively. In 1984 he received a doctoral degree in electricalengineering from the Paris-Sud University, Paris,

France. He joined the Electrical Engineering Depart-ment at the Federal University of Santa Catarina in1976, where he is currently professor of electrical engi-neering. His research interests include digital and ana-log filtering, image and speech processing, and digitalcommunications.

PAPERS

0 INTRODUCTION

The introduction of domestic multichannel sound repro-duction systems where the main channels include a fre-quency range of 20 Hz to 20 kHz and a special low-frequency effects (LFE) channel covering the frequencyrange of 20 Hz to 120 Hz has increased the demand forhigh-quality low-frequency sound reproduction. This isfurther emphasized by the fact that the LFE channel of the5.1 system is specified to sound pressure levels (SPLs) upto 10 – 12 dB relative to the level in the center channel.

The design of loudspeakers for high-quality low-frequency sound reproduction at high SPLs is a verydemanding task, involving complex mechanical, electri-cal, and acoustical problems. The optimum design of suchloudspeakers first requires detailed knowledge of thephysical interaction between the loudspeaker and theroom. Numerous investigations have been reported on this

issue, and the problems are fairly well described andunderstood (see [1] – [3] and references therein). Second itis necessary to understand how humans perceive low-frequency sound in small rooms and how perception isrelated to the physical properties of the sound field. Thishas also been an area with much activity; however, a sub-stantial number of problems still exist (see [4] – [16] andreferences therein).

As a part of the Medusa project a number of topics inlow-frequency sound reproduction were identified, whichwere characterized by a lack of, or poorly documented,understanding of the relationship between the physicalparameters and their perceptual importance. It wasdecided to investigate those areas in more detail, and theresults of these investigations are reported in two studies.This, the first, describes the results of the subjective exper-iments, and the second [17] describes the generation of thestimuli and the equalization of the experimental setup.

The work reported in parts I and II forms part of thestudies of the Eureka 1653 Medusa (Multichannel


Requirements for Low-FrequencySound Reproduction, Part I:

The Audibility of Changes in Passband Amplitude Ripple andLower System Cutoff Frequency and Slope*

SØREN BECH, AES Fellow

Bang & Olufsen a/s, DK-7600 Struer, Denmark

The audibility of changes in passband amplitude ripple and lower system cutoff frequencyand slope has been investigated for a loudspeaker system for two situations: a real loud-speaker in an anechoic chamber and a simulated system reproduced via headphones. Thesignals were standard program material, selected to ensure a sufficient energy content at therelevant frequencies. The experiments were conducted with six subjects with normal hearingusing a paired-comparison procedure. The subjects assessed the attributes “lower bass” and“upper bass” in relation to a fixed reference condition. The first experiment investigated theinfluence of high-pass filter order (second, fourth, and sixth) and lower cutoff frequency (20,35, and 50 Hz) at three reproduction levels and for four program items. The second experi-ment examined the influence of amplitude ripple corresponding to four reverberation times atthree reproduction levels and for four program items.

The results of the first experiment showed that the lower cutoff frequency has a significantinfluence on the perceived level of lower bass reproduction if the reproduction level is abovethe hearing threshold in the relevant frequency bands. The influence of high-pass filter orderwas not significant for the conditions investigated. The results of the second experimentshowed that the amplitude ripple has a significant influence on the perceived level of lowerand upper bass reproduction. The results also showed that there were no significant differ-ences between the data produced by the two reproduction methods.

* Manuscript received 2001 April 27; revised 2002 March 21.

PAPERS LOW-FREQUENCY SOUND REPRODUCTION, PART I

Enhancement of Domestic User Stereo Applications) proj-ect. The Medusa project was a 3.5-year joint researchproject with the following partners: British BroadcastingCorporation, Institute of Sound Recording of the Univer-sity of Surrey, Nokia Research Centre, Genelec Oy, andBang & Olufsen a/s.

1 EXPERIMENTAL STRATEGY

The purpose of the experiments was to identify andevaluate the perceptually important electrical/acousticalvariables required in the design of a loudspeaker systemfor high-quality reproduction of low-frequency sound insmall rooms. In order not to limit the applicability of theconclusions it was decided to assume that the system vari-ables were those available in a system employing digitalsignal processing (DSP) for all the filtering and controltasks.

The subjective experiments were planned to be con-ducted in the large anechoic chamber at the Department ofAcoustic Technology of the Technical University ofDenmark. In this room true free-field conditions exist forfrequencies above 44 Hz, and a specially designed loud-speaker, a so-called reference loudspeaker system, wasbuilt for the experiments. The details of this system arediscussed in [17]. However, as a large anechoic chamberis not generally available for normal development activi-ties, it would be advantageous if this type of experimentscould be conducted using, for example, headphone repro-duction instead. So in addition to conducting the experi-ments in the anechoic chamber it was decided to repeat theexperiments using reproduction by headphones, simulat-ing the reference system in the anechoic chamber. Theresults of the two reproduction methods could thus becompared, and if similar results were obtained, futureexperiments could be limited to headphone reproduction.

To guide the discussions on experimental design it wasdecided to consider the design variables in three separatefrequency ranges, as shown in Fig. 1. Note that this is onlyone of many possible divisions.

The frequency range is split into a lower part (1), a pass-band (2), and an upper part (3). The division is defined bythe limiting frequencies (4 and 5). Pedersen and Mäkivirta[17] present a more detailed discussion of the choice ofvariables, so here they are discussed only briefly.

The first two experiments, discussed here, only consid-ered the lower frequency part (1), the lower cutoff frequency(4), and the passband (2). The higher crossover frequency(5) and the filter order of the upper part (3) were fixed at 160Hz and fourth order in these experiments. The followingvariables were investigated in the first set of experiments:

a) Filter order of the high-pass filter (frequency range 1in Fig. 1)

b) Lower cutoff frequency (frequency range 4 in Fig. 1)c) Amplitude ripple in the lower and passband regions

(frequency ranges 1 and 2 in Fig. 1).The range of variation for variables a) – c) was selected

to be representative of the physical and electrical possibil-ities of practical loudspeaker designs. The following val-ues were chosen:

a) Filter order: second, fourth, and sixthb) Lower cutoff frequency: 20, 35, and 50 Hzc) Amplitude ripple: T60 0, 0.2, 0.4, and 0.8 s.Generation of the signals for the amplitude ripple con-

ditions was done using a simulation of the conditions in alistening room (see [17] for details). The ripples intro-duced by the room, however, will extend to higher fre-quencies than of interest for the present purpose. It wasthus decided to implement the ripples for two frequencyranges limited by the upper frequencies of 80 Hz and 120Hz, which are typical crossover frequencies for a subwoofersystem, and the specified crossover frequency for the LFEchannel of the 5.1 system, respectively. The implementationfrequency is thus added to the list of experimental variables.The target amplitude ripples are shown in Fig. 2.

It is important to note that variables a) – c) were orthog-onal, that is, they were varied independently of each otherin the experiment. Furthermore it was decided to investi-gate all factors at three SPLs for four program items.

In addition to the variables listed, the experiment alsoexamined the influence of delay ripple. However, due toan error in the implementation of the filters, the changes indelay ripple were not independent of the changes in ampli-tude ripple. The results of that part of the experiment arethus not considered here. However, the results for delayripple are presented and discussed in detail in [18].


Fig. 1. Division of frequency range for experimental design. Fora detailed discussion of parameters 1 – 5 see text. ––––– ideal-ized frequency response of LF part of loudspeaker system; – – –response of HF system.

Fig. 2. Target amplitude ripples implemented to either 80 or 120Hz. Top line at 60 dB corresponds to T60 0 s [0]. Other graphs,offset for reasons of clarity, represent T60 0.2 s [1], T60 0.4s [2], and T60 0.8 s [3], respectively. Numbers in brackets arethe identifications used in the experiment.

BECH PAPERS

The planning of the experiment showed that the opti-mum statistical experimental design would be to examinethe factors in two separate experiments. Filter order andlower cutoff frequency [a) and b)] were thus investigated inexperiment 1 and amplitude ripple [c)] in experiment 2.

2 PHYSICAL CONDITIONS

The description of the experimental setup in the ane-choic chamber and the details of the headphone systemcan be found in [17], so here only selected items will bediscussed.

2.1 SignalsThe selection of suitable signals is––as for any experi-

ment––important. The main criteria are suitability of thetask at hand and information content at the relevant fre-quencies. The suitability issue is concerned with the factthat a certain degree of repeatability of the signal or partsof the signal is necessary when using paired comparisonsbecause the subject is forced to switch between the twopresentations of the same program and to report based onthe comparison. The programs should, in addition to beingsuitable, contain energy in the frequency region of inter-est, which is the range of 20 – 120 Hz.

Both the suitability and the spectral informationrequirement could be fulfilled by designing an artificialsignal. However, it was decided that all programs shouldbe representative of the “real world,” that is, music orspeech signals. A large number of signals were thus ana-lyzed to determine their spectral properties at low fre-quencies (see Chapman [19] for details), and the most use-ful were selected, processed, and auditioned forsuitability. Seven pieces were selected, two for training ofthe subjects, four for the main experiment, and one (pinknoise) for calibration purposes. The selected programs arelisted in Table 1.

2.2 Calibration of Absolute and RelativeReproduction Levels

The choice of absolute reproduction level(s) wasdetermined by three main requirements (not in order ofimportance):

• The average level should be representative of normaldomestic listening levels.

• The loudspeaker should be operating within its specified

range at the maximum level, that is, no clipping or othernonlinear distortion should be present.

• The peak short-term SPLs should be above the hearingthreshold levels in the relevant frequency range.

Few published data exist on the average listening levelunder domestic conditions. Benjamin and Fielder [11] referto results from an unpublished survey, which found thepreferred dialog levels for television listening to be 60.5and 69 dB SPL, A-weighted, for home theater listening.

The maximum reproduction level was determined byapplying a nonprocessed version of the broad-band pinknoise signal to one of the reference loudspeakers posi-tioned in the anechoic chamber. The level was determinedby adjusting the input pink noise signal to be 2 dB belowthe clipping level1 of the loudspeaker system. This corre-sponded to 69 dB SPL (lin, slow) measured at the listen-ing position in the anechoic chamber and to approximately80 dB (lin, slow) at a listening position 2 m from the loud-speaker when the signal was applied to the reference loud-speaker placed in a standard listening room. The repro-duction levels are thus well below the levels where thesignificant distortion is generated by loudspeakers them-selves, as the loudspeaker has a harmonic distortion below2% in the frequency range of 20 –50 Hz and below 0.5%in the range of 50 –250 Hz (90 dB SPL at 1 m). See [17]for further details and note that these figures are well belowthe limits for harmonic distortion suggested by Fielder andBenjamin [11]. The corresponding loudness level at thelistening position was 22 sones, measured in the anechoicchamber according to ISO 532B [20] using a B&K 4133microphone and a B&K 2144 loudness analyzer.

The relationship between the maximum reproductionlevel per one-third octave and the hearing threshold levelfor all programs is shown in Fig. 3. The figure shows themaximum short-term SPLs (see Chapman [19] for furtherdetails) for one-third octaves over the entire program dura-tion. Also shown is the hearing threshold for free-field lis-tening conditions according to ISO 389 [21] for the rele-vant frequency range. The results show that all programswill have components above threshold down to approxi-mately 30 Hz at the highest reproduction level.

The two lower SPLs at 10 and 20 dB re the maxi-mum will thus lead to lower limiting frequencies of


1The clipping level was determined using Genelec’s built-inclipping indicator, the details of which are unknown.

Table 1. Specifications of selected program material.*

Experiment Main Record Duration PowerTitle Code Artist Company Record ID Track (min) (dB)

Rush Eric Clapton Reprise 926794-2 2 1 18.8Fourplay Fourplay Warner Bros. 7599-266565-2 10 1 12.9Ray of Light ray (1) Madonna Maverik/Warner Bros. 9362-46847-2 5 1 8.9Bladerunner bla (2) Vangelis East West 4509-96574-2 1 1 16.2The Hunter hun (3) Jennifer Warnes BMG 261974 9 1 13.9Amused to Death amu (4) Roger Waters Columbia 468761-2 3 1 25.3Pink noise 1 9.7

* The first two programs were used for training sessions, the next four for main experiment, and pink noise for calibration purposes.Power estimates were used for level alignment purposes.


35 – 45 Hz and 45 – 55 Hz, respectively. This suggests thatthe results for changes in lower cutoff frequency should beinterpreted with caution at the two lower levels. For thehighest reproduction level, with a limiting frequency of 30Hz, it is noted that there will still be a level difference at30 Hz between the amplitude responses with the 20 and 35Hz cutoff frequencies. Second, it is noted that the hearingthreshold curve represents the mean threshold of the stan-dard population. For the sake of completeness it wasdecided to use all reproduction levels in all experiments.

A careful calibration of the relative reproduction levelswas performed to avoid any biasing of the experimentalresults. The details of the procedure are described in [17],so only the main considerations will be given here. Levelcalibrations were performed at each of the three SPLs toremove differences in:

1) Loudness of the anechoic chamber and the head-phone setups

2) Loudness caused by different processing [variablesa) – c) in Section 1]

3) Loudness of the different programs.The loudness calibration of the two setups was done by

adjusting the transfer function for the headphone setupsuch that for reproduction of the same signal, the SPL atthe ear drum, in each ear, of a dummy head was identicalto that measured if the dummy head was placed at the lis-tening position in the anechoic chamber.

Different processing [see variables a) – c) in Section 1]results in differences in the reproduction levels for thesame input signal. These differences were removed byadjusting the gain factors for the processed versions of thebroad-band pink noise signal, so they all had a loudnesslevel of 22 sones. The gain factors so determined werethen applied to the processed program items.

The last set of calibration values was determined byremoving the differences in the average power levelsbetween the four programs. The power levels were usedinstead of loudness levels, as the standardized loudnessmeasure requires stationary signals. It is further noted thatthis calibration needs to be only approximate as differentprograms will not be compared directly during the exper-iment. Any differences between the programs will thushave a limited biasing effect. However, it is necessary tolimit the differences between programs to being smaller


Fig. 3. Maximum short-term SPLs for one-third octaves over entire program duration measured at listening position in anechoic cham-ber with both loudspeakers active at the highest reproduction level. Hearing threshold for free-field listening conditions according toISO standard 389 [21] for relevant frequency range is also shown. (a) bla. (b) amu. (c) hun. (d) ray.

(b) (d)

(c)(a)

BECH PAPERS

than the differences introduced by the three SPLs. Theaverage power spectra of the one-minute signals weremeasured and the relative gain adjustments determined(see Table 1).

The maximum reproduction level was thus 69 dB SPL(lin, slow) for all signals measured at the listening positionin the anechoic chamber. This corresponds to the averagelistening level for dialog in a home theater system accord-ing to Fielder and Benjamin [11]. This level will, however,not provide the listener with the so-called body impact,that is, a level where the low-frequency reproduction canbe perceived physically. It was considered more importantto operate within the constraints of the loudspeaker systemthan to create body impact in these experiments. If theexperimental results indicate that headphone reproductioncan be substituted for the anechoic chamber setup, it ispossible to repeat the experiment using significantlyhigher levels and still maintain low distortion levels, butstill without the body-impact factor.

2.3 Background Noise LevelThe background noise level in the anechoic chamber is

below the threshold of hearing in the frequency range ofinterest. The setup for the headphone reproduction exper-iment had the subjects seated in an audiometric booth toensure that the background noise level was sufficientlylow not to influence the listening tests.

3 EXPERIMENTAL PROCEDURE

3.1 ListenersSix listeners, all students at the Technical University of

Denmark, participated in the main experiments, and theywere paid an hourly rate for their services. Their hearingabilities were checked prior to the experiments to ensurethat they had hearing thresholds within2 10 dB re ISO 389[22]. The members of the permanent listening team at Bang& Olufsen and staff from the acoustics development depart-ment participated in the pilot experiments. These listenersall have extensive experience in listening tests, includingevaluation of low-frequency sound reproduction.

3.2 Test ProcedureA paired-comparison paradigm with a fixed reference

was used for both the anechoic and the headphone tests.This paradigm was selected because initial tests indicatedthat the subjective differences were small and thus a fairlysensitive procedure was needed. The fixed-reference optionwas chosen because a complete paired-comparison experi-ment required too large an experimental effort of the sub-jects. The fixed reference in the first experiment wasdefined by a cutoff frequency of 35 Hz and a fourth-orderfilter. In the second experiment an amplitude ripple corre-sponding to free-field conditions defined the referencestimulus.

In both experiments the subject’s task was to comparethe variable stimulus B to the fixed reference A and to

grade B with respect to A for two questions using a 5interval scale with one-decimal resolution. The questionswere

1) Has B more or less lower bass compared to A?2) Has B more or less upper bass compared to A?

The concepts of lower and upper bass were made famil-iar to the subjects by written instructions during the train-ing experiment, and by continuous discussion with theexperimenter.

A positive rating means that B has more of the givenattribute compared to A and a rating of 0 means that A andB have equal amounts of the attribute. It is noted that thesequestions are not related to the quality of the upper andlower bass but only to the magnitude of the attribute.Other details of the experimental setup related to the testprocedure are discussed in part II [17].

The selection of questions 1) and 2) was based on aseries of pilot experiments where the subjects were askedto rate the perceived changes in the form of five questionsthat covered the audible frequency range––lower bass,upper bass, lower midrange, upper midrange, and treble.The subjects were familiar with this division of the fre-quency range, and they had been trained in using this ter-minology, on a weekly basis, for years. The results clearlyshowed that the introduced changes did not have a signif-icant influence on the perceived sound related to the fre-quency bands characterized by the lower and uppermidrange and treble. Thus to reduce the experimentaleffort of the subjects it was decided to retain only thelower and upper bass questions.

3.3 Familiarization and Training ExperimentTo familiarize the subjects with the differences included

in the main experiments, each subject participated in train-ing sessions, one for the headphones and one for the loud-speaker experiment. The subjects could, using a multiple-comparison procedure, switch between seven stimuliselected to be representative of the nine stimuli fromexperiment 1 or sixteen from experiment 2. The trainingexperiment was based on two pieces of program materialthat were not included in the main experiment (see Table1). The subjects controlled the duration of the training ses-sion as they could continue until they felt confident thatthey could hear differences between the stimuli available.

3.4 Statistical Experimental DesignTo avoid any problems with temporary threshold shift,

it was decided to keep the reproduction level constant dur-ing a session. This means that SPL is a blocking factor inthe experimental design. For the second experiment it wasfurther decided to use the upper frequency limit of theimplementation (80 or 120 Hz) as another blocking factor.

The experimental design for the first experiment was asfollows. The factors are filter order (three levels), lowercutoff frequency (three levels), programs (four levels), andreproduction level (three levels). This results in nine com-binations of filter order and cutoff frequency, equal to ninecomparisons as the reference is compared against itself,for each of the four programs plus a repetition of thewhole experiment. Each subject is thus asked to make 72


2Three cases of 15 dB at a single frequency, for one ear,were accepted.


comparisons at each SPL. Pilot experiments showed thatone comparison takes on average 45 – 60 s, which meansthat one session would last close to an hour. It was there-fore decided to split a session into sessions a and b, whichwould be conducted consecutively, separated only by ashort break (15 – 30 min).

The presentation order of the stimuli was randomizedacross the a and b sessions. Assignment of the reproduc-tion levels to subjects and sessions followed a Latin squarestrategy. The combined a and b sessions thus represent acomplete factors experiment for the factors filter order F,lower cutoff frequency L, and program P. The factors sub-ject S and reproduction level R define the Latin squaremodel. The complete ANOVA model for experiment 1 foreach of the two questions is thus

Rating general mean S R F L P F * L F * P L * P residuals . (1)

Note that all factors are considered fixed, and only second-order interactions have been included. Residuals includethe effects of the repetition and the effect of the breakbetween the a and b sessions. This design, albeit with dif-ferent randomization for each subject, was used for boththe headphone and the loudspeaker experiments. Note thatthe design includes the reference stimuli in the group to bepresented to the subject. This allows for a check of thesubject’s ability to identify a known reference in a groupof unknown stimuli.

The original experimental design for the second exper-iment was as follows. The factors are amplitude ripple A(four levels), delay ripple D (four levels), reproductionlevel R (three levels), programs P (four levels), and imple-mentation frequency I (two levels). Reproduction leveland implementation frequency are blocking factors, andthe experiment was repeated once. A complete factorexperiment in one session would thus include 128 com-parisons (4 4 4 2) for each subject. However, asnoted for experiment 1, this is too many comparisons forone session, so it was decided to split the 128 comparisonsinto four blocks and introduce a blocking factor.Experiment 2 was thus designed as a split–split–plotexperiment, where reproduction level and implementationfrequency are the two splits and the plot is a blocked (4)complete factorial design. This design was used for eachsubject S (six levels), which then represents the “replica-tion” in the traditional experimental design terminology.The same design was used for both the headphone and theanechoic experiments. Note that the reference stimulus isincluded in the group of stimuli to be presented to the sub-ject. As for experiment 1, this allows for checking the sub-ject’s ability to identify a known stimulus.

The statistical analysis of the data for the amplitude rip-ple factor is complicated by the fact that the delay ripplefactor was included in the original experimental design asshown, but due to an error in the implementation of thesignal processing it cannot be included in the analysis. Theproblem is that changes in delay ripple were accompaniedby small changes in amplitude, so it is not possible to sep-arate the effects of the delay ripple and the amplitude

changes. The original statistical design included a block-ing factor, which cannot be included in the analysis whenthe delay ripple factor is not included. So it is necessary toassume that there was no significant effect due to theblocking of the experiment. This was verified in the analy-sis reported in [18].

The complete analysis of variance (ANOVA) model forexperiment 2 for each of the two questions is thus

Rating general mean R I A P S 2nd-order interactions residuals . (2)

All factors, except subject S, are considered fixed in theanalysis, and only the results for delay ripple D 0 areanalyzed.

4 RESULTS

4.1 Lower Cutoff Frequency and Filter OrderThe data for headphone and loudspeaker reproduction

were analyzed individually for each SPL by multivariateanalysis of variance (MANOVA) using the model given inEq. (1) for the dependent variables lower bass and upperbass. The significant ( p < 0.05) factors were (see Bech[18] for details of the MANOVA):

• Headphone reproductionUpper bass: lower cutoff frequency C (9), program P(5), and subject S (3)Lower bass: lower cutoff frequency C (51) , and subjectS (3)

• Loudspeaker reproductionUpper bass: lower cutoff frequency C (5), program P(5), and subject S (7)Lower bass: lower cutoff frequency C (56) , program P(7), and subject S (10).

The F values3 are given in parentheses, and it is noted thatthe same significant factors were found using a MANOVAmodel without the subject factor.

It is assumed that the statistical design ensures that theobservations are independent and that they originate fromnormal distributions with the same variance. However, itis noted that the ANOVA model is robust to deviationsfrom normality as long as the distributions are symmetri-cal. The distributions of the residuals were examined forboth dependent variables and the two reproduction meth-ods. The analysis showed that only for one situation(headphones, upper bass) were the residuals normally dis-tributed. The other distributions were symmetrical, buthad too long tails. The symmetry requirement is, as noted,the most important, so it is assumed that the results of theanalysis are valid.

The results for the significant factors are summarized inFig. 4 for the headphone data and in Fig. 5 for the loud-speaker data. Note that the data are presented for each pro-


3The F value determines, together with the number of degreesof freedom for the factors involved, the significance level of thefactor––the higher the F value, the more significant the factor

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Fig. 4. Scale values based on headphone reproduction as a function of cutoff frequency and reproduction level. Shown are mean val-ues averaged across subjects and filter order. Also shown are 95% confidence intervals based on error variance for each situation.(a) Lower bass. (b) Upper bass.

(a)

(b)



Fig. 5. Scale values based on loudspeaker reproduction as a function of cutoff frequency and reproduction level. Shown are mean val-ues averaged across subjects and filter order. Also shown are 95% confidence intervals based on error variance for each situation.(a) Lower bass. (b) Upper bass.

(b)

(a)

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gram and SPL despite the fact that neither of these factorswas significant. However, the discussion in Section 2 indi-cated that the interaction between SPL and program fac-tors could cause problems for the interpretation. Thus toclarify this issue, it was chosen to represent this interac-tion in the graphs.

First it is noted that the subjects have been able to iden-tify the reference stimuli included in the stimuli presented.The reference stimulus has a 35-Hz cutoff frequency, andit is noted that only for three situations (lower bass––pro-gram 2, 49-dB SPL, loudspeaker reproduction, and pro-gram 2, 69-dB SPL, headphones; and upper bass––pro-gram 3, 69-dB SPL, headphones) are the mean valuessignificantly (only slightly) different from a scale value of0. This is encouraging as it adds to the validity of the dataset and the experimental procedure.

The results show that for the highest reproduction levelthere is a significant increase, when compared to the ref-erence, in the perceived level of lower bass for both head-phone and loudspeaker reproduction for all programswhen the cutoff frequency is lowered from 35 to 20 Hz.However, there is only a significant decrease in the per-ception of lower bass for an increase in cutoff frequencyfrom 35 to 50 Hz for program 1.

There is also a significant difference between the per-ceived levels of lower bass for the 20- and 50-Hz cutofffrequencies for both reproduction methods and all pro-grams, except for loudspeaker reproduction and program3. It is noted, however, that the two conditions were notdirectly compared in the experiment, so in theory theresults should not be compared. However, if it is assumedthat the rating scale is linear in the range considered, thecomparison is meaningful.

As noted in Section 2.2, caution should be exercisedwhen interpreting the results for the two lower reproduc-tion levels. The results indicate that for lower bass there isa significant effect of lowering the cutoff frequency from35 to 20 Hz for program 2. For program 3 there are sig-nificant differences at both reproduction levels for loud-speakers and at 49 dB for headphones. However, there isno significant effect for an increase in the cutoff frequencyfrom 35 to 50 Hz for any situation tested.

The results for upper bass show that only in a few casesis there any significant influence of changes in the lowercutoff frequency.

4.2 Amplitude RippleThe data for headphone and loudspeaker reproduction

were analyzed individually using the MANOVA model inEq. (2) for the dependent variables lower bass and upperbass and a delay ripple of 0. The subject factor wasincluded as both a random and a fixed factor. However,there were no differences between the identity and thenumber of significant factors for the two situations. Theresults reported in the following are based on a model thatincludes subject as a fixed factor.

The distributions of the residuals were analyzed and theresults showed that the distributions were symmetrical,but had tail that were too long compared to the normal dis-tribution. This is similar to the observations for the distri-

butions of the residuals in experiment 1, as discussed inthe previous section. The results of the analyses were thusconsidered to be valid. The analyses showed that theresults for lower and upper bass include the same mainsignificant factors, so the following discussion applies toboth attributes. The two reproduction methods also pro-duced the same set of main factors, the only differencebeing that implementation frequency was only found sig-nificant for headphone reproduction.

The significant factors are, in order of importance,amplitude ripple R, program P, reproduction level R, andthe interaction between amplitude ripple and program.Other interactions were found to be significant, but their Fvalues were markedly smaller than those of the main fac-tors. The results can thus be summarized as shown in Figs.6 – 8.

The results for lower and upper bass are shown inFig. 6 for headphone reproduction, and in Fig. 7 forloudspeaker reproduction. First it is noted that theresults for an amplitude ripple of 0 are not significantlydifferent from 0 for any of the tested conditions exceptfor upper bass, headphone reproduction, 69 dB, andprogram bla. That means that the subjects have beenable to identify the reference stimuli included in thepresented group of stimuli. This was expected, based onthe results of the first experiment (see Section 4.1).However, it still adds further credibility to the experi-mental procedure and subjects.

The results show that, in general, an amplitude ripplehigher than 2 is needed4 to increase the impression oflower bass to a significant degree compared to the refer-ence situation of 0. This applies to all SPLs and programsexcept program bla, where an amplitude ripple of 3 isneeded. For programs amu and ray it is seen that signifi-cantly higher levels of lower bass can be found for anamplitude ripple of 1. It is also seen that the rate of changein lower bass increases with increasing reproduction lev-els for all programs except bla.

A comparison between the results for lower and upperbass shows that the changes introduced in amplitude rip-ple have mainly influenced the perceived level of lowerbass.

The implementation frequency factor and its interactionwith the SPL were significant for the headphone-baseddata, and the results are shown in Fig. 8. The results showthat the significance of the factor is caused by the signifi-cant difference between the lower bass levels for ampli-tude ripple 1 and SPL 59 dB.

4.3 Comparison of Headphone and LoudspeakerReproduction

The preceding discussion shows that the statisticalanalysis produced the same significant factors for bothreproduction methods, the only differences being that pro-gram was not significant for headphone reproduction andlower bass in the first experiment, and implementation fre-quency was not significant for loudspeaker reproduction


4See Fig. 2 for the relation between number code and magni-tude of the implemented ripples.



Fig. 6. Scale values based on headphone reproduction as a function of amplitude ripple for four programs and three reproduction lev-els. Shown are mean values averaged across subjects and implementation frequency for a delay ripple of 0. Also shown are 95% con-fidence intervals based on error variance for each situation. (a) Lower bass. (b) Upper bass.

(b)

(a)

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Fig. 7. Scale values based on loudspeaker reproduction as a function of amplitude ripple for four programs and three reproduction lev-els. Shown are mean values averaged across subjects and implementation frequency for a delay ripple of 0. Also shown are 95% con-fidence intervals based on error variance for each situation. (a) Lower bass. (b) Upper bass.

(b)

(a)


in the second experiment. The analysis further showedthat subjects were most sensitive to the changes intro-duced for the attribute lower bass, so those results will beused for a comparison between the two reproductionmethods. The mean scale values for lower bass for head-phone and loudspeaker reproduction are shown in Figs.9 – 12 for the main significant factors in the two experi-ments. The results show that the two reproduction meth-ods do not produce significantly different results in any ofthe situations tested.

5 DISCUSSION

5.1 Lower Cutoff Frequency and Filter OrderThe discussion in Section 2.2 noted that while the high-

est reproduction levels were above the hearing threshold atfrequencies down to approximately 30 Hz, this was not thecase for the two lower levels, and this should be consid-ered carefully before making any firm conclusions. Theresults in Figs. 4(a) and 5(a) for lower bass confirm this.At the highest level there is a significant effect of lower-ing the cutoff frequency from 35 to 20 Hz for all four pro-grams, whereas for the lowest level there is only a signif-icant effect for programs 2 and 3. For program 2 this canbe explained by the 5 – 7-dB increase in spectrum level forthe frequency range of 30 – 40 Hz compared to the level in

the range of 50 – 100 Hz, as shown in Fig. 3(b). The con-sequence is that the lower limiting frequencies at the twolower levels are approximately 32 and 42 Hz for 59 and 49dB, respectively. The significant effect for program 3 can-not be explained by properties of the spectrum.

The results thus indicate that the examined changes incutoff frequency lead to significant changes in the per-ceived level of lower bass if the reproduction level isabove the hearing threshold level.

The correlation between the results for the perceivedlevels of lower and upper bass is low, but significant at0.24 ( p < 0.01) due to the high number of observations. Alow correlation was expected as the physical changes inthe spectrum were introduced in a frequency range thatwould presumably correspond to the lower bass only. Thisis supported by the results shown in Figs. 4(b) and 5(b),where it is seen that the magnitude of the perceivedchanges in upper bass are insignificant for most of thetested situations. However, the trend is similar to thatobserved for lower bass.

The low-frequency part of the program spectra, shownin Fig. 3, has characteristics similar to those of a high-passfilter with a sixth-order slope. This explains why there isno significant effect of filter order for the two lowest cut-off frequencies at 20 and 35 Hz for any of the reproduc-tion levels. However, for the highest reproduction level


Fig. 8. Scale values based on headphone reproduction for lower bass as a function of amplitude ripple for SPLs and implementation(IMP) frequencies. Shown are mean values averaged across subjects and programs for a delay ripple of 0. Also shown are 95% confi-dence intervals based on error variance for each situation.

BECH PAPERS

and a cutoff frequency of 50 Hz it could be expected tofind a larger influence of filter slope. This is confirmed bya closer inspection of the results for the 50-Hz cutoff fre-quency, which shows the largest influence, although notsignificant, of filter slope for any of the situations tested.

The results thus indicate that the order of the high-passfilter characteristics of the loudspeaker system will nothave a significant influence for cutoff frequencies lowerthan 50 Hz and programs with spectra similar to thosetested.


Fig. 10. Comparison of scale values for lower bass for headphone (HP) and loudspeaker (LS) reproduction for amplitude ripple exper-iment. Shown are mean values for four programs and reproduction level of 69 dB, averaged across subjects and implementation fre-quency for a delay ripple of 0. Also shown are 95% confidence intervals based on error variance for each situation. Note that scalingof y axis has been optimized for each program.

Fig. 9. Comparison of scale values for lower bass for headphone (HP) and loudspeaker (LS) reproduction for lower cutoff frequencyexperiment. Shown are mean values for four programs averaged across subjects, reproduction level, and filter order. Also shown are95% confidence intervals based on error variance for each situation.



Fig. 12. Comparison of scale values for lower bass for headphone (HP) and loudspeaker (LS) reproduction for amplitude ripple exper-iment. Shown are mean values for four programs and reproduction level of 49 dB, averaged across subjects and implementation fre-quency for a delay ripple of 0. Also shown are 95% confidence intervals based on error variance for each situation. Note that scalingof y axis has been optimized for each program

Fig. 11. Comparison of scale values for lower bass for headphone (HP) and loudspeaker (LS) reproduction for amplitude ripple exper-iment. Shown are mean values for four programs and reproduction level of 59 dB, averaged across subjects and implementation fre-quency for a delay ripple of 0. Also shown are 95% confidence intervals based on error variance for each situation. Note that scalingof y axis has been optimized for each program.

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5.2 Amplitude RippleA number of investigations on the audibility of fre-

quency response irregularities have been reported, andFielder and Benjamin [11], Toole and Olive [10], andOlive et al. [13] have good summaries of the previousresults. However, only Olive et al. investigated the fre-quency range below 85 Hz, so there are few data to com-pare against directly.

Fielder and Benjamin suggest, based on an extrapola-tion of available results, that the just-noticeable difference(JND) in level for a 70.7% detection criterion and pulsedsinusoids in the frequency range below 80 Hz will be inthe range of 1.5 – 1 dB for reproduction levels of 5 – 40 dBabove the hearing threshold. Toole and Olive [10] showsthat the threshold of detection for a single nondelayed res-onance with a Q value of 1, and using the most criticalprogram material (pink noise), corresponds to a steady-state output level of the added resonance of 25 to 30dB re the program level for the frequency range of 100 Hzto 10 kHz. They further find, using the least critical pro-gram material (popular music), that the threshold of detec-tion increases to 10 dB re program level for a resonance(Q 1) at 1 kHz. Their results also indicate that a dou-bling of the Q value increases the threshold of audibilityby approximately 3 dB. Olive et al. [13] determined thedetection threshold for resonances and antiresonances at500, 250, 125, and 63 Hz using pink noise and 10-ms-wide pulses at a repetition rate of 10 Hz. Their resultsbasically confirmed the findings of previous researchers,Bücklein [6] shows that peaks in the frequency responseare more audible than the equivalent valleys and found a100% detection rate for a 5-dB peak (Q 10) centered at85 Hz and using white noise.

The results in Figs. 6(a) and 7(a) shows that an ampli-tude ripple of 1 leads to a significant change in lower bassin approximately 40% of the tested situations. For anamplitude ripple of 2 there are significant changes inapproximately 75% of the tested situations, and for anamplitude ripple of 3, 100% of the tested situations leadsto a significant change. This suggests that the threshold ofdetection (50%) corresponds to an amplitude ripple that ishigher, but close to 1. The implemented amplituderesponse corresponding to 1 is shown in Fig. 13. It can beassumed that the two peaks at approximately 58 and 70 Hzare determining the threshold because peaks are moreaudible than dips (Bücklein [6]), and the upward spread ofmasking means that peaks and valleys higher in frequencyare likely to be masked. The Q of both peaks is approxi-mately 2.9, with maximum levels of 3.2 and 3 dB re thereference (0).

Translation of these values into something that is com-parable with previous results requires a consideration ofthe bandwidth of the auditory system below 100 Hz.Moore [23] presents a summary of recent data suggestingthat, extrapolated to frequencies around 60 Hz, the criticalbandwidth is 30 Hz (equivalent rectangular bandwidth).The relative energy change in a critical band centeredaround the two peaks (50 – 80 Hz) can thus be calculatedto 2.11 dB for the 1 situation.

To compare this with the results of Toole and Olive [10]and Olive et al. [13], the relative change in energy for the1 situation was transformed by calculating the correspon-ding steady-state output of a single added resonance rela-tive to the reference level. The resonance had a Q value of2.9 (second order) and was centered at 63.2 Hz, and thecorresponding steady-state output of the resonance wascalculated to be 8.2 dB, corresponding to an energychange of 2.11 dB. Toole and Olive [10] found a thresholdvalue of approximately 10 dB for a single resonancewith a Q value of 1 at 1 kHz, and Olive et al. [13] found athreshold (70.7%) value of approximately 13 dB for aresonance with Q 1 at 63 Hz. Using the results that adoubling of Q increases the threshold by 3 dB, it followsthat Toole would have found a threshold value of 5.6 dBand Olive et al. would have found a threshold value ofapproximately 8.6 dB (13 dB 3 * 1.45) for a reso-nance with Q 2.9. These values are comparable to theobserved value of 8.2 dB, as it is noted that both Toole& Olive et al. determined the detection threshold,whereas the current “threshold” value is based on thecondition that the situation is not significantly differentfrom the reference situation. It is thus not possible tocompare values directly, but it is noted that the values areof similar size.

Similar calculations for an amplitude ripple of 2 resultin a corresponding steady-state output of a single addedresonance (Q 7.3) of 3.5 dB. This value can be com-pared to 4.6 dB based on results by Olive et al. This sug-gests that condition 2 should be above the threshold, andthis is in agreement with the observed results.

The observed threshold level of 2.1 dB is higher thanthe JND value predicted by Fielder and Benjamin, buttheir JND value is based on pulsed sinusoids, which mustbe assumed to be more critical (that is, lower thresholds)compared to real program material.

The results for lower bass given in Figs. 6(a) and 7(a)show that the influence of the reproduction level is higherfor amplitude ripple 3 than for 2. This can be explained bythe nonlinearity of the upward spread of masking (see, forexample, Fielder and Benjamin [11] for a detailed discus-sion of masking for low frequencies). It is further noted


Fig. 13. Amplitude ripples implemented for condition 1.


that the influence of the reproduction level is not signifi-cant for amplitude level 1 for any of the programs. This isimportant as it suggests that the threshold value is inde-pendent of the reproduction level for the range of SPLstested.

The influence of program was expected although greatcare was taken to ensure that the “suitability” of each pro-gram was high. The programs have similar levels of low-frequency energy (see Fig. 3 and discussion in Section2.2), so the observed lack of discriminative power of pro-gram bla must be the result of a nonideal time pattern forthat program. The subjects did report that they had prob-lems with this program, but were not specific regardingthe detailed reason.

The lack of influence of implementation frequency canbe explained as follows. The spectral difference betweenusing the two implementation frequencies can be seen inFig. 2. A 120-Hz limit means that the spectral valley atapproximately 100 Hz is included, whereas the 80-Hzlimit means that it is not included. The upward spread ofmasking of the hearing will, however, mask the main partof the valley when it is included in the spectra, and thelimited sensitivity to valleys (see Bücklein [6]) will furtherreduce their influence.

6 CONCLUSIONS

The audibility of changes in the lower system cutoff fre-quency and slope, and in passband amplitude ripple, hasbeen investigated for a loudspeaker system for two situa-tions––a real loudspeaker in an anechoic chamber and asimulated system reproduced via headphones. The testsignals were real program material, selected to ensure asufficient energy content at the relevant frequencies. Theexperiments were conducted with six subjects with normalhearing using a paired-comparison procedure. The sub-jects evaluated the magnitude of lower bass and upperbass in relation to a fixed reference condition.

The first experiment investigated the influence of high-pass filter order (second, fourth, and sixth) and lower cut-off frequency (20, 35, and 50 Hz) at three reproductionlevels and for four programs. The second experimentexamined the influence of amplitude ripple correspondingto four reverberation times at three reproduction levels andfor four programs.

The results of the first experiment showed that thelower cutoff frequency has a significant influence on theperceived level of lower bass if the reproduction level isabove the hearing threshold in the relevant frequencyrange. The influence of the high-pass filter order was notfound to be significant for the conditions investigated.

The results of the second experiment showed that thethreshold of audibility for changes in the perceived levelof lower bass corresponds to a peak amplitude ripple ofapproximately 3 dB re the reference transfer function.The threshold level is independent of the reproductionlevel, whereas the influence of higher amplitude ripplesincreases with increasing reproduction level. The generalaudibility of the amplitude ripple also depends on thesignal.

A comparison of the results for the two reproductionmethods showed that the two methods produced resultsthat were not significantly different. This suggests thatfuture experiments can be conducted using reproductionby headphones if the headphone system simulates theloudspeaker system employed in the anechoic chamber. Anumber of issues, such as influence of reproduction level(that is, lack of body impact) when using headphones,other types of manipulations of the low-frequency transferfunction, and internal versus external localization of thesound event need to be examined before general conclu-sions can be drawn about the similarity between the tworeproduction methods for subjective experiments on low-frequency reproduction.

7 ACKNOWLEDGMENT

The members of the Medusa group are thanked formany fruitful discussions. The author would like to thankPeter Chapman, Gert Munch, David Ward, Poul ErikTrabjerg, and John Usher, all from B&O, for countlesshours of intense effort in establishing the experimentalsetup, calculating the signal modifications, and runningthe experiments. The author would especially like to thankJan Abildgaard Pedersen for many hours of intense DSPwork, checking all the .wav files and processing. Finally,all the students are thanked for their participation in theexperiments.

8 REFERENCES

[1] Audio, Acoustics and Small Spaces, Proc. AES 15thInt. Conf. (Audio Engineering Society, New York, 1998).

[2] A. Groh, “High Fidelity Sound System Equalizationby Analysis of Standing Waves,” J. Audio Eng. Soc., vol.22, pp. 795 – 799 (1974 Dec.).

[3] T. Salava, “Subwoofers in Small Listening Rooms,”presented at the 106th Convention of the Audio Engin-eering Society, J. Audio Eng. Soc. (Abstracts), vol. 47, p.527 (1999 June), preprint 4940.

[4] J. Blauert and P. Laws, “Group Delay Distortion inElectroacoustical Systems,” J. Acoust. Soc. Am., vol. 63,pp. 1478 – 1483 (1978).

[5] D. Preis, “Phase Distortion and Phase Equalizationin Audio Signal Processing––A Tutorial Review,” J. AudioEng. Soc., vol. 30, pp. 774 – 794 (1982 Nov.).

[6] R. Bücklein, “The Audibility of Frequency Response Irreg-ularities,” J. Audio Eng. Soc., vol. 29, pp. 126 –131 (1981 Mar.).

[7] S. P. Lipshitz, M. Pocock, and J. Vanderkooy, “On theAudibility of Midrange Phase Distortion in Audio Systems,”J. Audio Eng. Soc., vol. 30, pp. 580 – 595 (1982 Sept.).

[8] L. R. Fincham, “The Subjective Importance of Uni-form Group Delay at Low Frequencies,” presented at the74th Convention of the Audio Engineering Society, J.Audio Eng. Soc. (Abstracts), vol. 31, pp. 971, 972 (1983Dec.), preprint 2056.

[9] J. Borenius, “Perceptibility of Direction and Time-DelayErrors in Subwoofer Reproduction,” presented at the 79thConvention of the Audio Engineering Society, J. Audio Eng.Soc. (Abstracts), vol. 33, p. 1008 (1985 Dec.), preprint 2290.


THE AUTHOR

BECH PAPERS

[10] F. E. Toole and S. E. Olive, “The Modification ofTimbre by Resonances: Perception and Measurement,”presented at the 83rd Convention of the Audio Engin-eering Society, J. Audio Eng. Soc. (Abstracts), vol. 35, pp.1050, 1051 (1987 Dec.), preprint 2487.

[11] L. D. Fielder and E. M. Benjamin, “SubwooferPerformance for Accurate Reproduction of Music,” J.Audio Eng. Soc., vol. 36, pp. 443 – 456 (1988 June).

[12] C. Kügler and G. Thiele, “Loudspeaker Reproduct-ion: Study on the Subwoofer Concept,” presented at the92nd Convention of the Audio Engineering Society, J.Audio Eng. Soc. (Abstracts), vol. 40, p. 437 (1992 May),preprint 3335.

[13] S. E. Olive, P. L. Schuck, J. G. Ryan, S. L. Sally,and M. E. Bonneville, “The Detection Thresholds ofResonances at Low Frequencies,” J. Audio Eng. Soc., vol.45, pp. 116 –128 (1997 Mar.).

[14] T. Nousaine, “Multiple Subwoofers for HomeTheater,” presented at the 103rd convention of the AudioEngineering Society, J. Audio Eng. Soc. (Abstracts), vol.45, p. 1015 (1997 Nov.), preprint 4558.

[15] S. Linkwitz, “Investigating of Sound-QualityDifferences between Monopolar and Dipolar Woofers inSmall Rooms,” presented at the 105th Convention of theAudio Engineering Society, J. Audio Eng. Soc.(Abstracts), vol. 46, p. 1032 (1998 Nov.), preprint 4786.

[16] N. Zacharov, S. Bech, and D. Meares, “The Use of Sub-

woofers in the Context of Surround Sound Program Reproduc-tion,” J. Audio Eng. Soc., vol. 46, pp. 276 –287 (1998 Apr.).

[17] J. A. Pedersen and A. Mäkivirta, “Requirementsfor Low-Frequency Sound Reproduction, Part II: Genera-tion of Stimuli and Listening System Equalization,” J.Audio Eng. Soc., vol. 50, pp. 581 – 593 (this issue).

[18] S. Bech, “Quantification of Subwoofer Require-ments, Part II: The Influence of Lower System Cut-offFrequency and Slope, and Pass-band Amplitude andGroup Delay Ripple,” presented at the 109th Conventionof the Audio Engineering Society, J. Audio Eng. Soc.(Abstracts), vol. 48, p. 1101 (2000 Nov.), preprint 5199.

[19] P. J. Chapman, “Programme Material Analysis,”presented at the 100th Convention of the AudioEngineering Society, J. Audio Eng. Soc. (Abstracts), vol.44, p. 652 (1996 July/Aug.), preprint 4277.

[20] ISO 532, “Method for Calculating LoudnessLevel,” International Standards Organization, Geneva,Switzerland (1975).

[21] ISO 389-7, “Reference Threshold of Hearing underFree-Field and Diffuse-Field Listening Conditions,” Inter-national Standards Organization, Geneva, Switzerland (1996).

[22] ISO 389(E), “Standard Reference Zero for theCalibration of Pure Tone Air Conduction Audiometers,” Inter-national Standards Organization, Geneva, Switzerland (1985).

[23] C. J. Moore, An Introduction to the Psychology ofHearing, 4th ed. (Academic Press, London, 1997).


Soren Bech received an M.Sc. in 1982 and a Ph.D. in1987, both from the Department of Acoustic Technology(AT) at the Technical University of Denmark. From 1982to 1992 he was a research fellow at AT, studying percep-tion and evaluation of reproduced sound in small rooms.

In 1992 he joined Bang & Olufsen as a technologyspecialist, and in June 2001 became a senior technologyspecialist responsible for the corporate activities in per-ception. In 2000 he was appointed an adjunct professorat McGill University, Faculty of Music, and in 2001 avisiting professor at the University of Surrey, Institute ofSound Recording. He has done research in, and has beenproject manager of several international collaborativeresearch projects including Archimedes (perception ofreproduced sound in small rooms), ADTT (AdvancedDigital Television Technologies), Adonis (image qualityof television displays), LoDist (perception of distortionin loudspeakers units), Medusa (multichannel sound

reproduction systems), and Vincent (flat-panel displaytechnologies).

Dr. Bech was co-chair of the ITU task group 10/3 anda member of task group 10/4, member of the organizingcommittee and editor of a symposium on “Perception ofReproduced Sound” in 1987, member of the Danish AESSection board (1986 – 88), section chair (1988 – 90), chairof the AES 12th Conference in 1992, member of theorganizing committee for the AES 100th Convention in1996, papers co-chair for the AES 15th Conference in1998, and AES governor (1996 – 98).

Dr. Bech is currently AES vice-president, NorthernRegion Europe (2001 – 2003), chair of the AESConference Policy Committee, and member of thereview board of JAES, JASA, and Acta Acoustica. He is afellow of the AES and the Acoustical Society of America.He has published numerous papers in JAES, JASA, andother scientific journals.

ENGINEERING REPORTS

0 INTRODUCTION

The aim of this work was to study the psychoacousti-cally determined performance requirements for the designof a loudspeaker system for high-quality reproduction oflow-frequency sound in small rooms.

This is part II in a series of papers, and it describes howdigital signal processing was used for the generation ofstimuli and the equalization of the listening system. Part Idescribed the actual listening experiments, includingexperimental strategy, procedure, and results [1].

The increasing use of digital surround sound systems,such as 5.1 systems, increases the attention to low-frequency reproduction. Considering 5.1 systems, espe-cially the .1 channel and modern program material, loud-speaker manufacturers have the desire to quantify therequirements for low-frequency sound reproduction.

In order not to limit the applicability of the conclusionsit was decided to assume that the system variables werethose available in a system employing digital signal pro-cessing (DSP) for all the filtering and control tasks.

The essential requirements for high-quality soundreproduction at low frequencies are the lower cutoff fre-quency and slope because these are linked to maximumdisplacement of drivers, system tuning, and powerrequirements. In this context it was also decided to focuson two additional parameters––amplitude ripple andgroup delay ripple, both in the passband. Amplitude ripplesets the requirements for how much the amplituderesponse can be allowed to deviate from an ideal response.Requirements regarding maximum group delay rippleimpose a limit on how rapidly the phase is allowed tochange. Both amplitude and delay ripple can arise due toa number of physical phenomena such as variations in theparameters of the loudspeaker drive units, resonances inthe cabinet, diffraction around the cabinet, reflections, and


Requirements for Low-Frequency SoundReproduction, Part II:

Generation of Stimuli and Listening System Equalization*

JAN ABILDGAARD PEDERSEN, AES Member

Research & Development, Bang & Olufsen a/s, DK-7600, Struer, Denmark

AND

AKI MÄKIVIRTA, AES Member

Genelec Oy, FIN-74100 lisalmi, Finland

In part I of two papers the requirements for low-frequency sound reproduction were inves-tigated by the variation of lower cutoff frequency and slope and by the introduction of differentlevels of amplitude ripple and group delay ripple in the passband of a high-performance soundreproduction system. Listening tests were performed at three different sound pressure levelsusing both loudspeakers in an anechoic chamber and headphones in an audiometric booth.Two reproduction setups were used to confirm that equal results of the listening tests couldbe obtained in the two cases when proper equalization was implemented.

It is described how DSP was used to generate stimuli and perform equalization of the tworeproduction setups. The shape and magnitude of amplitude and group delay ripple werederived from room simulations of an IEC 268-13 sized room with varying reverberation time.Proper equalization included the introduction of head-related transfer functions in the signalpath to the headphones. This ensured that the sound pressures at the ear drums were verysimilar in two cases––a person sitting in front of the loudspeakers in the anechoic chamberand a person wearing headphones in the experimental booth. Level calibration wasperformed on both setups using pink noise. The nonlinearities measured in the physicalloudspeakers were introduced into the signal path to the headphones using a nonlinearitysimulator program.

* Manuscript received 2001 April 27; revised 2002 March 22.

PEDERSEN AND MÄKIVIRTA ENGINEERING REPORTS

modes in the listening room. The experiments weredivided into two separate groups––lower cutoff frequencyand slope in the first group and amplitude and group delayripples in the second group. All parameters in each groupwere required to be varied independently, that is, orthogo-nally.

The work reported both here and in paper I formed partof the EUREKA Project 1653 Medusa (MultichannelEnhancement of Domestic User Stereo Applications). TheMedusa project was a 3.5-year joint research project withthe following partners: British Broadcasting Corporation,Institute of Sound Recording at University of Surrey,Nokia Research Centre, Genelec Oy, and Bang & Olufsena/s.

1 GENERATION OF STIMULI

Stimuli for the listening tests were produced by differ-ent filtering of seven selected program pieces. First thelower cutoff frequency and slope were changed and thenboth amplitude and group delay ripples in the passbandwere added.

1.1 Program MaterialSeven items of program material were selected from a

wide set of materials [1]. Two items were used during thetraining of subjects, whereas four other items were used inthe actual experiment. The last item was used for calibra-tion purposes only. The spectral distribution, especiallybelow 200 Hz, was of special interest when selecting theseven items of program material. Table 1 lists the specifi-cations for the selected seven pieces.

Total loudness at the listening position was used to cal-ibrate the playback level. The calculation of total loudnessrequired a stationary signal, which was chosen to be pinknoise, as seen in Table 1. The reproduction level of pinknoise was adjusted from loudness measurements, whichare described in Sections 3.1 and 3.3, and the levels of theother six pieces were individually adjusted relative to pinknoise, based on calculations of the total power content ofthe seven pieces. Eq. (1) gives the relative gain GA of pro-

gram item A relative to pink noise,

pink

G

A n

n

P

P

pinkA

n

N

n

N

A2

0

1

2

0

1

!

!

7

7

A

A

(1)

where pink [n] is the time signal of pink noise and A[n] thetime signal of program item A, N is the number of samplesin the program pieces, Ppink is the total power content ofpink noise, and PA is the total power content of programitem A. The total power content is given in Table 1 foreach of the seven pieces.

Power spectra of all the program items were calculatedusing the 1 min of each program item. Fig. 1 gives thepower spectra of the two training items and Fig. 2 those ofthe four items that were used in the actual experiment. Theoriginal program items were turned into Microsoft wavefiles with two channels, 16 bits, and 44 100-Hz samplingfrequency. All the programs for processing had Microsoftwave files as both input and output files.

1.2 Variable Lower Cutoff Frequency and SlopeThe lower cutoff frequency was varied from 20 to 50

Hz by prefiltering the program material using a digitalhigh-pass filter with variable cutoff frequency. The rangefrom 20 to 50 Hz was considered to be a typical range oflower cutoff frequencies. An intermediate value of 35 Hzwas chosen as a third cutoff frequency. Additional infor-mation about the experimental plan was presented in partI [1]. Fig. 3 illustrates the variation of the lower cutofffrequency.

It is not only the cutoff frequency that is of importancewhen considering the lower rolloff of a loudspeaker sys-tem, but also the order, that is, slope. A closed-box systemis of second order and a vented box is of fourth order.Considering these very commonly used systems, it waschosen to vary the order of the high-pass filter betweensecond, fourth, and sixth order. Fig. 3 shows this variationof the slope from second order up to sixth order.


Table 1. Specifications of selected program material.*

Main Record Power†Title Artist Company Number Track Time (dB)

Rush Eric Clapton Reprise 926794-2 2 0:00 18.81:00

Fourplay Fourplay Warner Bros. 7599-266565-2 10 0:25 12.91:25

Ray of Light Madonna Maverik/Warner Bros. 9362-46847-2 5 0:40 8.91:40

Bladerunner Vangelis East West 4509-96574-2 1 1:00 16.22:00

The Hunter Jennifer Warnes BMG 261974 9 3:40 13.9 4:40

Amused to Death Roger Waters Columbia 468761-2 3 0:05 25.31:05

Pink noise 0:00 9.71:00

* The first two programs were used during training and the following four during the actual experiment. Pink noise was used forcalibration.†Power averaged over the whole duration of each program item. Only relative levels were necessary for level alignment of pro-gram pieces.

ENGINEERING REPORTS LOW-FREQUENCY SOUND REPRODUCTION, PART II

1.3 Amplitude and Group Delay RippleRipples both in amplitude response and in the group

delay are found in practical usage of loudspeaker systems.Ripples can arise for a number of reasons, such as toler-ances of components, limited possibilities of equalization,

poor tuning of the system, diffraction of the cabinet, reflec-tions, and modes in the listening room. When designingand installing a loudspeaker system, it would be useful tohave knowledge about how large the ripples are allowed tobe. Ripples of different magnitudes were added to the testitems before playback by introducing a digital filter com-


Fig. 2. Power spectrum (one-third) of four music segments for actual test (aligned).

Fig. 1. Power spectrum (one-third) of first two music segments for training (aligned).


prising a nonflat amplitude response or a nonlinear phaseresponse. A nonflat amplitude response in the passband ofthe loudspeaker yielded amplitude ripple and a nonlinearphase response yielded a nonconstant group delay, that is,group delay ripple.

The shape and magnitude of both amplitude and groupdelay ripple were calculated from room simulations of anIEC 268-13 sized room [2]. The room simulations werebased on the principle of mirror images and carried outusing a developed program [3]. The room simulator pro-gram was used to calculate the first 1000 ms of theimpulse response in a specified receiver position, given aspecified source position. Both source and receiver wereassumed to be omnidirectional. The impulse response wassampled at a rate of 4 kHz, which was appropriate consid-ering the bass region of a loudspeaker system.

The simulated room was a rectangular room with dimen-sions of 5.03 m 6.02 m 2.50 m (width length height). The source position was chosen to be (X, Y, Z) (0.30 m, 0.40 m, 0.35 m), which was considered to be arealistic corner position that would excite all room modes,which in turn would yield large ripples. The receiver posi-tion was chosen to be at a typical listening position nearthe center of the room, but offset about 0.30 m to avoidabnormal effects due to perfect symmetry, such as perfectcancellation: (X, Y, Z) (2.20 m, 2.70 m, 1.10 m).

These parameters of the room simulation were fixed inall simulations, but the reverberation time T60 was variedfrom an anechoic environment to 0.8 s in order to controlthe magnitude of the ripples, that is, a hard room yieldedlarge ripples compared to a well damped room. The rever-beration times of the simulated rooms were estimated by

time-reversed integration of the squared impulse response.Eq. (2) was used to calculate a Schroeder integral plotrp[n], based on the impulse response h[n], which was oflength N,

.rp n h ii n

N2

!7 7A A (2)

Further information about time-reversed integration canbe found in [4]. The reverberation time T60 was foundthrough inspection of a plot of the Schroeder integral bydetermining the time where the level was decreased 60dB relative to the initial level. Note that the length of thesimulated impulse response was longer than the truereverberation time in order to avoid errors in theSchroeder integration.

Four levels of ripples were calculated by simulatingfour rooms with different reverbation times T60: 0 s (ane-choic), 0.2 s, 0.4 s, and 0.8 s. The reverberation time wasadjusted by changing the reflection coefficients of thewalls, floor, and ceiling. Table 2 lists the reflection coeffi-cients for the six surfaces in each of the four rooms. Theamplitude and phase responses of each room were nor-malized according to the anechoic room, that is, the ane-choic case yielded zero amplitude ripple and zero groupdelay ripple. The group delay was calculated from theunwrapped phase response by differentiation. Figs. 4 – 6show all four levels of amplitude ripple and group delayripple. Please note that ripples were only implementedfrom these target curves up to a certain upper frequency,that is, to emulate the upper frequency limit of a sub-


Table 2. Reflection coefficients of walls, floor, and ceiling

T60 Walls Floor Ceiling

Anechoic 0.000 0.000 0.0000.2 s 0.650 0.440 0.2900.4 s 0.805 0.540 0.3600.8 s 0.895 0.600 0.400

Fig. 3. Variation of cutoff frequency and slope.



Fig. 6. Group delay ripple in four cases. From top––anechoic, T60 0.2 s, T60 0.4 s, T60 0.8 s. Both 80 and 120 Hz are markedas upper limits for implementing the ripples. For clarity, 0-s level has been shifted to 600 s, 200 s, 200 s, and 600 s, respectively,as indicated by bold horizontal lines.

Fig. 5. Amplitude ripple implemented up to 120 Hz in four cases. From top––anechoic, T60 0.2 s, T60 0.4 s, T60 0.8 s. For clar-ity, 0-dB level has been shifted to 60 dB, 20 dB, 20 dB, and 60 dB, respectively, as indicated by bold horizontal lines.

Fig. 4. Amplitude ripple implemented up to 80 Hz in four cases. From top––anechoic, T60 0.2 s, T60 0.4 s, T60 0.8 s. For clar-ity, 0-dB level has been shifted to 60 dB, 20 dB, 20 dB, and 60 dB, respectively, as indicated by bold horizontal lines.


woofer. Two upper frequency limits were implemented toinvestigate the influence of the range in which rippleswere implemented: 80 Hz as indicated in Fig. 4, and 120Hz as indicated in Fig. 5. Both 80 Hz and 120 Hz are indi-cated for the group delay ripple in Fig. 6. 80 Hz was con-sidered to be a typical crossover frequency for a sub-woofer and 120 Hz was the specified crossover frequencyfor the low-frequency enhancement (LFE) channel of a5.1-channel system.

In order to minimize the influence of loudness differ-ences between the four different amplitude ripple filters, itwas decided to normalize the total power relative to theanechoic filter, that is, 0-dB filter. The power of eachamplitude ripple filter was calculated in the frequencyrange from 20 to 80 Hz in Fig. 4 and from 20 to 120 Hz inFig. 5. Then a pure gain was applied to the individual fil-ters in order to obtain equal total power in the specifiedfrequency ranges.

1.4 ImplementationVariation of the lower cutoff frequency and slope was

implemented using digital high-pass filters with variablecutoff frequency of second, fourth, and sixth order accord-ing to the experimental design [1].

The amplitude and group delay ripple filters weredesigned based on the impulse responses produced by thesimulated room response calculations found in Section1.3. Only ripples in the bass range were included, mean-ing that ripples in amplitude and delay were only includedup to a certain frequency, and no ripples existed above thisfrequency.

The experimental design [1] had three variables for theripples: the limiting frequency below which the ripplesexist (two values), the amount of amplitude ripple (fourvalues), and the amount of delay ripple (four values).

Two filter designs for each value of the reverberationtime were then produced––a linear phase filter, whichcontained the amplitude ripples but no delay ripples, andan all-pass filter, which contained just the delay ripplesand no amplitude ripples. The delay filters were madecausal by adding a constant delay.

The experimental design [1] used the amplitude rippledata from one reverberation time simulation, combinedwith the delay ripple data from any of the four reverbera-tion times. This was implemented by convolving an ampli-tude filter with a delay filter, producing one filter for eachof the amplitude/delay deviation combinations. The filtershad a sampling rate of 4410 Hz. The filter length was 2.04s (8996 samples) when it contained both amplitude anddelay ripple.

The audio files containing the desired deviations wereproduced using a multirate convolution process. The audiodata were crossover filtered at one of the two desired fre-quencies, the low-pass section was convolved with the rip-ple filters described, and the final signal was produced bysumming the two signals with the necessary gain anddelay alignment. For delay ripple filtering, the delay align-ment could not be exact over the whole crossover fre-quency band, and this produced changes in the amplitudeand delay properties at the crossover point (maximum 1.5

dB). The introduction of delay ripple also introducedsome unwanted amplitude ripple. But the opposite was notthe case, that is, the introduction of amplitude ripple didnot introduce any unwanted delay ripple. It follows fromthis that amplitude ripple and delay ripple were not com-pletely orthogonal, and as a consequence it was decidednot to use the test results obtained from the stimuli whereany delay ripple was introduced [1].

The convolution was performed in floating-point arith-metic, and the source and destination files were 16-bitfixed point, sampling frequency 44.1 kHz. The low-passsection was processed at a sampling frequency of 4410 Hz(decimation by 10). Distortion and noise levels were stud-ied at each step of the process, and proper dithering wasapplied at quantizations to maintain linearity throughoutthe processing chain and to minimize noise.

2 EXPERIMENTAL SETUPS

The experiments were carried out using two differentsetups––loudspeakers in an anechoic chamber and head-phones in quiet surroundings.

2.1 Setup in Anechoic ChamberThe processed audio samples were played back using a

pair of reference loudspeakers built especially for this pur-pose. These reference loudspeakers extended down to 20Hz (2.5 dB) and kept the harmonic distortion below 2%(90 dB SPL at 1 m) at low frequencies, in the range from20 to 50 Hz. Above 50 Hz, in the range from 50 to 250 Hz,the harmonic distortion was below 0.5% (90 dB SPL at 1m). Above 50 Hz the group delay was kept below 10 ms,in the frequency range from 50 Hz to 20 kHz. The groupdelay was kept below 20 ms in the full frequency range,from 20 Hz to 20 kHz. It was an active three-way closed-box system. Crossover frequencies were 160 Hz and 1.6kHz (fourth order). The separate power amplifiers for thethree bands were 400 W, 160 W, and 120 W.

The setup comprised two reference loudspeakers and alistening position placed in a 3-m equilateral triangle in alarge anechoic chamber, as shown in Fig. 7. The subjectswere seated in a chair. Both loudspeakers and the chairwere placed on grids that were held in place by poles


Fig. 7. Setup in anechoic chamber, comprised of two referenceloudspeakers and a chair for listening. Both loudspeakers andchair were placed on grids held in place by poles extending to thebottom of the anechoic chamber.


extending to the bottom of the anechoic chamber. The ane-choic chamber is located at the Technical University ofDenmark, Department of Acoustic Technology. The freespace in the anechoic chamber is about 1000 m3. The threedimensions are of similar magnitude, but not equal, andthe lower limiting frequency is 43.7 Hz. A detaileddescription can be found in [5].

A computer-based system for automated control of thelistening tests was utilized. The system is known asGuineaPig [6], [7]. This software was run in a workstation(Silicon Graphics Octane) that included eight channels of24-bit (ADAT) input and output. Graphical user interfaceand feedback from the subject were handled by a laptopPC connected to the workstation.

Control of analog level and conversion from digital toanalog were performed using a digital mixing console(YAMAHA O3D). This mixer utilized 20-bit linear 8oversampling digital-to-analog converters. Fig. 8 showsan overview of the entire signal path starting at the origi-nal program pieces located on the original Compact Discs(CDs). The program material from the original CDs wasprocessed prior to the listening experiments and put ontothe hard disk of the workstation. During the actual listen-ing experiments the program material was taken from thehard disk of the workstation.

2.2 Headphone SetupAs an alternative to using an anechoic chamber, head-

phones were utilized in an attempt to simulate the setup in

the anechoic chamber. A number of different headphoneswere tested and an electrostatic type was chosen(Sennheiser HE 60, electrostatic, amplifier SennheiserHEV 70). This choice was motivated by a wide frequencyresponse and low distortion.

Fig. 9 gives measurements of the distortion of the head-phone at a maximum level of 100 dB SPL. The head-phones were placed on a Brüel & Kjær head and torsosimulator (B&K 4128), and measurements were takenusing a Brüel & Kjær audio analyzer (B&K 2012). Thehead and torso simulator was mounted with hard ears(optional). Measurements took place in an anechoic cham-ber at Bang & Olufsen. The levels of both second and thirdharmonics were generally more than 75 dB (0.02%) belowthe fundamental, except for a number of frequencieswhere the level was 60 dB (0.1%) below the fundamental.The levels of both second and third harmonics rose toabout 50 dB (0.3%) below the fundamental at 20 Hz.

During listening experiments, subjects were seated inquiet surroundings, an audiometric booth. The audiomet-ric booth was located next-door to the anechoic chamberdescribed in Section 2.1.

In an attempt to simulate the reference loudspeakers inthe anechoic chamber, it was decided to include a nonlin-ear simulation of the reference loudspeakers, that is, dis-tortion due to nonlinearities of the reference loudspeakerwas added to the signals before playback using the head-phones. Section 3.2 describes how a nonlinear simulatorprogram was used to perform this simulation. The sound


Fig. 9. Fundamental, second, and third harmonics measured with head and torso simulator and headphones used in the experiment.Maximum SPL at 9 kHz was 100 dB.

Fig. 8. Signal path from original CD to playback in anechoic chamber using reference loudspeakers. Program material from CD wasprocessed prior to listening experiments and put onto hard disk of workstation.


pressures at the ear drums in the two setups were madesimilar by applying advanced equalization to the signalsbefore playback via the headphones. Section 3.3 describesthis equalization in detail. Fig. 10 shows the signal pathwhen headphones were used. The graphic user interfaceand feedback from the subject were handled directly bythe workstation.

3 LISTENING SYSTEM EQUALIZATION ANDCALIBRATION

The setup in the anechoic chamber was measured usingpink noise, and calibration was performed. Both the non-linearities of the loudspeaker and the difference in lineartransfer functions of the headphones compared to listen-ing in the anechoic chamber were taken into account in theequalization process.

3.1 Anechoic ChamberThe middle curve in Fig. 11 shows a measurement of

the left reference loudspeaker placed in the anechoicchamber according to Fig. 7. The measurement was takenusing a free-field microphone (B&K 4133), measurementamplifier (B&K 2690: NEXUS), and an audio analyzer

(B&K 2012). The free-field microphone was placed at thelistening position pointing directly toward the left refer-ence loudspeaker. The first mode of the anechoic chamberis clearly seen in Fig. 11 at approximately 35 Hz, whichwas a frequency so low that the damping in the room wasinsufficient to be anechoic. This mode was unavoidable,so it was decided to leave the system like it was and takethe response in Fig. 11 as part of the circumstances for theexperiment.

During the listening experiment three different play-back levels, spaced 10 dB between each level, were used.The highest level was found by applying full-scale pinknoise, and adjusting the level to 2 dB below the levelwhere clipping is indicated on the rear of the loudspeaker.Adjusted to this level, a sound pressure level of 69 dB (lin,slow) was measured using the free-field microphone at thelistening position, when pink noise was applied to the leftreference loudspeaker. In an IEC 268-13 standard listen-ing room [2], this adjustment corresponded to approxi-mately 80 dB (lin) sound pressure level.

Still using the free-field microphone and playing thepink noise, the loudness level was measured to 22 sonesvia a loudness meter (B&K 2144). This loudness meterwas based on ISO 532B “Zwicker” loudness [8]. When a


Fig. 11. Transfer functions. From top––left loudspeaker to left ear, left loudspeaker to right ear, left loudspeaker to free-field micro-phone, left headphone and right headphone both mounted on head and torso simulator. Curves were shifted apart to increase clarity.Free-field microphone measurement was lowered 30 dB relative to HRTFs, e.g., left loudspeaker to left ear.

Fig. 10. Signal path from CD to playback in audiometric booth using headphones. Program material from CD was processed prior tolistening experiments and put onto hard disk of workstation.


1-kHz sine wave, full scale on a CD, was applied usingthis adjustment, 78.4 dB (lin) was measured via the free-field microphone. The two lower playback levels weresimply 10 and 20 dB below this adjusted level.

3.2 Nonlinear SimulationA nonlinear simulation of the reference loudspeaker

was utilized when playback was performed using head-phones. This ensured that distortion due to nonlinearitiesof the reference loudspeaker was added to the signalsbefore playback using the headphones. This operation wasperformed using a nonlinear loudspeaker driver simulatorprogram (LoDist) [9].

The central parameter in this nonlinear simulator pro-gram was the diaphragm position, that is, the traditionalloudspeaker driver parameters were dependent on thediaphragm position. All relevant parameters were deter-mined as a function of absolute displacement from theneutral position. Measurements were performed on awoofer driver identical to the ones used in the referenceloudspeakers. Based on these parameters, the nonlinearsimulator program solved numerically the differentialequations that described the loudspeaker driver and itsenvironment, such as its cabinet. More information aboutmeasuring position-dependent parameters, and the opera-tion and principle of the nonlinear simulator program canbe found in [9].

Care was taken to ensure that the electrical voltageapplied to the simulated driver was identical to the voltageapplied to the physical driver in the reference loudspeaker.This was achieved by applying appropriate scaling whenrelating the digital signal feed to the nonlinear simulatorprogram and the corresponding analog voltage.

3.3 HeadphonesThe sound pressures at the ear drums in the two setups

were made similar by applying advanced equalization tothe signals before playback via the headphones. Head-related transfer functions (HRTFs) were measured in theanechoic chamber using the setup described in Section2.1. HRTFs are described in [10].

The HRTFs were measured using the left referenceloudspeaker and a head and torso simulator (B&K 4128)placed in the listening position in the anechoic chamber,facing a point just halfway between the loudspeakers. Thehead and torso simulator was used because it was assumedthat individual HRTFs for each subject in the listening testwere not necessary. This assumption was made becausetimbre was judged to be the important parameter, whereasexact location was judged to be a secondary issue.Especially at low frequencies, which was the importantfrequency range in this context, the individual HRTFs arevery similar, which lead to the choice of using a standardhead and torso simulator. Fig. 11 includes two HRTFmeasurements at the top of the figure––left loudspeaker toleft ear (the uppermost curve) and left loudspeaker to rightear. The shadow effect of the head is obvious above 400Hz, where left loudspeaker to left ear is much higher thanleft loudspeaker to right ear. Below 150 Hz both HRTFscoincide with the middle curve, the free-field microphone

measurement, but the curves are shifted 30 dB apart forclarity. Perfect symmetry of the acoustic setup wasassumed when right loudspeaker to right ear and rightloudspeaker to left ear were obtained, but differences inthe sensitivities of the two ears of the head and torso sim-ulator were taken into account.

The selected headphones were placed on the head andtorso simulator, and the transfer functions to each ear weremeasured. These amplitude responses are shown at thebottom of Fig. 11. As described in Section 3.2, a nonlinearsimulator program was used to simulate the nonlinearbehavior of a loudspeaker driver, but to do so accurately,it had to have the correct linear response as well, that is,the linear response of the reference loudspeaker. But thelinear response of the reference loudspeaker was alsoincluded in the measured HRTFs––transfer functionsfrom the input of the loudspeakers to the output of thehead and torso simulator. For this reason an inverse filterof the linear transfer function of the nonlinear simulatorprogram was included in the equalization in order to can-cel one of the two linear transfer functions of the referenceloudspeakers found in the signal chain.

The linear transfer function of the nonlinear simulatorprogram was found by feeding an audio file, containing adigital Dirac impulse, through the nonlinear simulatorprogram. This was done at a signal level that did not giverise to displacements of an order where nonlinearitiescome into play, such as a small fraction of 1 mm. Fig. 12shows the determined amplitude response along with abold curve, which has limited attenuation toward lowerfrequencies. This limitation below 15 Hz was used toavoid dynamic/numerical problems when the transferfunction was inverted.

The placement of the digital filter can be seen in Fig.10, where the filter is marked with EQ. The filter wasdesigned from the measured HRTFs, the transfer functionof headphones on the head and torso simulator, and thelinear transfer function of the nonlinear simulator pro-gram. The digital filter was used to process the signals,which were meant for playback via the reference loud-speakers, in such a way that the output signals from thedigital filter were ready for playback via headphones. Thiswas performed so that the sound pressures at the eardrums of the head and torso simulator were identical in thetwo setups––headphones mounted on the head and torsosimulator and the head and torso simulator placed in theanechoic chamber in front of the reference loudspeakers.

During calibration with pink noise, the function of thedigital filter EQ was somewhat different. Section 3.1described how the pink noise signal was played back viathe reference loudspeakers and how the sound pressurewas measured by a free-field microphone. In this situationthe digital filter was used to process the pink noise signalso that the electrical output of the head and torso simula-tor wearing the headphones was identical to the electricaloutput of the free-field microphone in the anechoic cham-ber, when the loudspeakers were playing the unprocessedpink noise. This was necessary because the loudness meterused required an input signal from a free-field microphonein order to calculate the correct loudness level.



Fig. 13 summarizes all the considerations regarding thecalculation of the digital equalizer filter EQ in the twocases––playback of program pieces, namely, using themeasured HRTFs, and calibration with pink noise,namely, using the free-field microphone measurement.

When a human is listening to two loudspeakers, each ofthe two ears receives sound coming from both loudspeak-ers––crosstalk from both loudspeakers to both ears. Fig.14 shows a schematic of how this was achieved using fourindividual filters for each equalizer EQ when the programpieces were processed, that is, the equalizer for the pro-gram pieces consisted of the four filters, HRR, HRL, HLR,and HLL.

HRR was calculated from the ratio of the HRTF from theright loudspeaker to the right ear divided by the product ofthe transfer function of the right headphone and the lineartransfer function of the nonlinear simulator program . HRLwas calculated using the HRTF from the right loudspeakerto the left ear, the left headphone, and the linear transferfunction of the nonlinear simulator program. HLR and HLLwere calculated accordingly. The equalizer for the pink

noise did not have crosstalk, that is, only two equalizer fil-ters, because the HRTFs were replaced by the free-fieldmicrophone measurements. Due to the assumption of per-fect acoustic symmetry, the numerator in Fig. 13 wasexactly the same for both right and left loudspeakers. Theonly difference was between the two headphones, that is,in the denominator in Fig. 13.

Fig. 15 shows all four filters that formed the equalizerfor the program pieces, HRR and HLL being the two uppercurves in the frequency range from 400 to 8000 Hz. Fig.16 shows the two filters that formed the equalizer for thepink noise. All measurements were taken using 1/24octave logarithmic frequency resolution, and the filterswere designed using an FFT size of 65 536. This called forinterpolation, which was performed in the complex planeafter removal of the pure time delays of all the relevanttransfer functions. After interpolation, all pure time delayswere reintroduced to ensure the correct time responses.The final impulse responses of the equalizer filters weretruncated after 10 000 samples. Filtering was then per-formed using a convolution program developed for this


Fig. 13. Calculation of equalization filters EQ for either programmaterial using HRTF measurements or pink noise using free-field microphone measurements.

Fig. 14. Four different filters used to generate signals for head-phone playback based on two signals for loudspeaker playback.

Fig. 12. Measured linear transfer function of nonlinear simulator program. Transfer function was limited below 15 Hz to avoid highgains when implementing inverse filter.


purpose, based on floating-point arithmetic.The fixed-point nature of the audio files, that is, 16 bits,

was taken into account by down-scaling the equalizer fil-ters appropriately and reintroducing the removed gains inthe conversion process to analog signals. The level cali-bration was performed by adjusting the gain of the digitalmixing console, so that the resulting loudness level was 22sones. This corresponded to a sound pressure level of 69dB (lin) for one channel playing the processed pink noise.

This calibration and the equalization ensured that thetransfer function for the headphone setup was adjustedsuch that for the reproduction of the same signal, thesound pressure level at the ear drum in each ear of adummy head was identical to that measured if the dummyhead was placed at the listening position in the anechoicchamber.

4 CONCLUSION

Seven program pieces were processed using DSP inorder to prepare the program pieces of the listening exper-

iments, described in part I [1]. Pink noise was used to cal-ibrate the loudness level of the two setups––referenceloudspeakers in an anechoic chamber and headphones inan audiometric booth. Three different reproduction levelswere used, all 10 dB apart. The loudest level was cali-brated to 22 sones, which corresponded to 69 dB SPL forone channel playing in the anechoic chamber.

Three different lower cutoff frequencies were imple-mented–– 20 Hz, 35 Hz, and 50 Hz––combined withthree different orders/slopes––second, fourth, and sixthorder. Based on room simulations, four different levels ofamplitude ripples and group delay ripples in the passbandwere implemented. Amplitude ripples varied between 0and 20 dB, and group delay varied between 0 and 200ms. These variations were found by varying the reverber-ation time T60 from anechoic to 0.8 s in room simulationsof an IEC 268-13 sized room. When delay ripple wasintroduced, some unwanted amplitude ripple was alsointroduced (maximum 1, 5 dB). No unwanted delay ripplewas introduced when amplitude ripple was introduced.

In an attempt to have similar conditions in the two


Fig. 16. Amplitude response of two filters used to process pink noise before calibration of headphone setup.

Fig. 15. Amplitude response of four filters used to generate signals for headphone playback based on signals for loudspeaker playback.

THE AUTHORS


setups, advanced equalization of the signals and simula-tion of the nonlinear behavior of the woofer drivers wereperformed before the signals were fed to the headphones.The equalization was based on measurements of HRTFs inthe anechoic chamber, the transfer function of the refer-ence loudspeakers using a free-field microphone, thetransfer function of headphones mounted on a head andtorso simulator, and the linear transfer function of the sim-ulator program for the nonlinear simulation of loud-speaker drivers. All signal processing was performeddirectly on audio files.

5 ACKNOWLEDGMENT

The authors would like to thank their colleagues inEUREKA Project 1653, Medusa, for countless fruitfuldiscussions and valuable ideas. Great effort was shown,and large tasks were carried out by our colleagues, whomthe authors would like to thank: Gert Munch, PeterChapman, and David Ward at Bang & Olufsen and AriVarla at Genelec. The authors would especially like tothank Søren Bech from Bang & Olufsen for outstandingenthusiasm and general view of the whole process. Inaddition the authors would like to thank the Department ofAcoustic Technology at the Technical University ofDenmark for the use of their large anechoic chamber andfor practical support with the measurement setup.

6 REFERENCES

[1] S. Bech, “Requirements for Low-Frequency SoundReproduction, Part I: The Audibility of Changes inPassband Amplitude Ripple and Lower System CutoffFrequency and Slope,” J. Audio Eng. Soc. vol. 50, pp.564 – 580 (this issue).

[2] IEC 268-13, “Sound System Equipment,” Part 13:“Listening Tests on Loudspeakers,” International Electro-

technical Commission, Geneva, Switzerland (1985).[3] J. A. Pedersen, K. Hermansen, and P. Rubak, “The

Distribution of the Low Frequency Sound Field and ItsRelation to Room Equalization,” presented at the 96th Con-vention of the Audio Engineering Society, J. Audio Eng.Soc. (Abstracts), vol. 42, p. 408 (1994 May), preprint 3852.

[4] F. Jacobsen and J. H. Rindel, “Time Reversed DecayMeasurements,” J. Sound Vibration, vol. 117, pp. 187 –190 (1987).

[5] F. Ingerslev, O. J. Pedersen, P. K. Møller, and J.Kristensen, “New Rooms for Acoustic Measurements atthe Danish Technical University,” Acustica, vol. 19, pp.185 – 199 (1967/1968).

[6] N. Zacharov, J. Huopaniemi, and M. Hämäläinen,“Round Robin Subjective Evaluation of Virtual HomeTheater Sound Systems at the AES 16th InternationalConference,” in Spatial Sound Reproduction, Proc. AES16th Int. Conf. (1999), pp. 544 – 556.

[7] J. Hynninen and N. Zacharov, “GuineaPig––AGeneric Subjective Test System for Multichannel Audio,”presented at the 106th Convention of the AudioEngineering Society, J. Audio Eng. Soc. (Abstracts), vol.47, p. 513 (1999 June), preprint 4871.

[8] ISO 532, “Method for Calculating Loudness Level,”International Electrotechnical Commission, Geneva,Switzerland (1975).

[9] E. Sandermann Olsen, “Nonlinear Modeling ofLow-Frequency Loudspeakers––A Practical Implement-ation,” presented at the 102nd Convention of the AudioEngineering Society, J. Audio Eng. Soc. (Abstracts), vol.45, p. 414 (1997 May), preprint 4469.

[10] K. Inanaga, Y. Yamada, and H. Koizumi, “Head-phone System with Out-of-Head Localization ApplyingDynamic HRTF (Head-Related Transfer Function),” pre-sented at the 98th Convention of the Audio EngineeringSociety, J. Audio Eng. Soc. (Abstracts), vol. 43, pp. 401,402 (1995 May), preprint 4011.


Jan Abildgaard Pedersen received a master's degree inelectrical engineering from the University of Aalborg inDenmark in 1993, where he specialized in acoustics.

After graduating, Mr. Pedersen began working atBang & Olufsen as a DSP research engineer in theElectroacoustics Research & Development department,

and since 1998 he has been a technology specialist foracoustics and DSP. In this capacity, he is not onlyresponsible for Bang & Olufsen following this technol-ogy area, but also contributes to the development of it.He works in many other research areas including low-frequency sound field, room equalization, near-field

J. A. Pedersen A. Mäkivirta



acoustic measurements, subwoofer requirements, andespecially what DSP has to offer in acoustic applica-tions. He is a member of the AES.

Aki Mäkivirta was born 1960 in Jyväskylä, Finland. Hereceived Diploma Engineer, Licentiate in Technology, andDoctor of Science in Technology degrees in electricalengineering from Tampere University of Technology,Tampere, Finland, in 1985, 1989 and 1992, respectively.His doctor’s thesis described applications of nonlinearsignal processing methods for haemodynamic monitoringin medical intensive care.

In 1983, Dr. Mäkivirta joined the Medical Engineering

Laboratory of the Research Center of Finland atTampere, where he worked in various research positionsin the field of biomedical signal analysis. In 1990 hejoined Nokia Corporation Research Center in Tampere,Finland, where he served as a project manager, and after1992 was the research manager responsible for building aresearch group for DSP applications in television audioand high-quality loudspeaker reproduction. In 1995 hejoined Genelec Oy, Iisalmi, Finland, where he is a R&Dmanager responsible for digital system and signal pro-cessing applications.

Dr. Mäkivirta is a member of the AES and IEEE. Heholds 13 patents, and he is the author of more than 40journal and conference papers.

ENGINEERING REPORTS

INTRODUCTION

Due to physical damages to the storage medium, trans-fer errors, or destructive signal processing, informationcan be lost from a portion of a signal. The portion of thesignal can be lost completely, resulting in a gap, or it canbe irreversibly distorted due to an impulsive disturbance. Insuch cases the samples in the disturbed portion do not con-tain any information about the original signal and shouldnot be used in calculating the reconstructed samples.Reconstruction of missing signal samples is a commonlyknown signal processing problem, and various methodshave been introduced to perform the task [1] – [6].

Our method is based on the time-domain signal extrap-olation described in [7]. The corrupted samples are replacedby a weighted average of the signals extrapolated from areaspreceding and following the missing or corrupted area. Inthis engineering report the correction method is applied inpractice to correct scratches in digital signals recordedfrom old damaged vinyl recordings.

From the mathematical theory of extrapolation [7] wecan obtain the requirements for signals that can be extrap-olated. By studying audio signals we notice that they donot exactly satisfy the requirements of being fully pre-dictable, and therefore they cannot be perfectly extrapo-lated. However, the audio signal nearly satisfies therequirements for short-time intervals, and good error cor-rection for missing or damaged audio signals up to thou-

sands of samples (with a sampling frequency of 44.1 kHz)can be achieved by using the proposed method.

1 RECONSTRUCTION OF MISSING SAMPLES

After a missing section has been located or an error inthe audio signal detected, the damaged samples are recon-structed by using the time-domain discrete signal extrapo-lation method described in [7]. The extrapolation is basedon first finding the impulse response of the signal (that is,modeling the signal) and then using a convolution-likeone-step extrapolation equation to generate the first newsample to the given signal vector by weighting and com-bining previous samples. This newly extrapolated sampleis added to the signal vector as a known sample, and theone-step extrapolation equation is used again to generatethe next new sample. By applying this procedure succes-sively, an unlimited number of new samples can be gener-ated. The signal is extrapolated across the missing seg-ment from both sides. A weighted average of the forwardand backward extrapolated signals is used to fill the miss-ing section in order to ensure a smooth transition when thesignal characteristics change within the missing segment.An example of the reconstruction of a missing audio sig-nal segment is presented in Fig. 1.

1.1 Signal ModelingPrior to extrapolation the audio signal must be modeled.

The signal is modeled by calculating its impulse response.The impulse response bears information about all the fre-


Reconstruction Method for Missing or DamagedLong Portions in Audio Signal*

ISMO KAUPPINEN AND JYRKI KAUPPINEN

University of Turku, Department of Physics, FIN-20014 Turku, Finland

An algorithm for the correction of disturbances or gaps of up to several thousand samplesin an audio signal is presented. The reconstruction is based on a novel method for time-domain discrete signal extrapolation. The missing or disturbed portion of the audio signal isreplaced by a weighted average of signals extrapolated from the areas preceding andfollowing the disturbed portion. Impulsive-type errors usually distort the underlying signalirreversibly, and the damaged signal portion does not contain any information of the originalsignal. In the proposed method the damaged signal samples are not used in computing thereplacing samples. The reconstruction method is applied in practice to correct scratches fromsignals recorded from badly damaged vinyl recordings. The proposed signal reconstructionmethod can be implemented in real-time applications.

*Manuscript received 2000 November 20; revised 2002 May16.

ENGINEERING REPORTS RECONSTRUCTION METHOD

quencies present in the signal and their amplitudeenvelopes. We derive the impulse response vectors hand h of the signal x before and after the missing sec-tion, respectively. The impulse response can be solvedanalytically from N 2M known signal samples with theequation

Xh x (1)

where h [h1, h2, . . . , hM]T, x [xM1, xM2, . . . ,x2M]T. The matrix X is composed of shifted signalsamples,

.

x

x

x

x

x

x

x

x

x

x

x

x

X

M

M

M

M

M

M

M

M

M M

1

2 1

1

2 2

2

1

2 3

1

2

h h h

f

f

f

h

J

L

KKKKKK

N

P

OOOOOO

(2)

However, the exact analytical solution for h exists onlyfor noiseless theoretical signals. For nonstationary noisysignals (such as audio signals) an iterative approachshould be used. A preferred method is to calculate first theaudioregressive (AR) model prediction error coefficientsof the signal and then convert them into impulse responsecoefficients. The AR prediction error coefficient vectora [a0, a1, a2, . . . , ap], where p is the model order, can

be converted into the impulse response vector by using theh [h1, . . . , hM] [a1, a2, . . . , ap] and p M. Arobust iterative method for finding the AR model coeffi-cients is the Burg method [8] – [10].

1.2 Extrapolation and Cross-FadeThe one-step forward extrapolation equation is

x h xn k n kk

M

1

! (3)

where xn is the forward extrapolated signal sample and his the impulse response vector derived from the area pre-ceding the error. After extrapolating the first new samplewith Eq. (3) and setting it as a known signal sample, wecan use Eq. (3) to extrapolate the next new sample.Repeating this process, we can extrapolate an unlimitednumber of new samples. The backward extrapolationequation is

x h xn k n kk

M

1

! (4)

where xn is the backward extrapolated signal sample andh is the impulse response vector derived from the areafollowing the error. The missing section is replaced by aweighted average of the forward and backward extrapo-


Fig. 1. Large section of a signal (a) from acoustic guitar is zeroed (b) and reconstructed using proposed method (c). Length of zeroedportion–– 3006 samples (0.068 s). Reconstructed signal (c) is subtracted from original signal (a), and resulting error signal is plottedin (d).

(d)

(a)

(c)

(b)

KAUPPINEN AND KAUPPINEN ENGINEERING REPORTS

lated signals. A weighting function wn is used to producethe cross-fade of the forward and backward extrapolatedsignals. The signal replacing the damaged portion is givenby

x w x w x1 n n n n nt _ i (5)

where xn and xn are the forward and backward extrapo-lated signal samples, respectively. The weighting functionwn satisfies the condition 0 ≤ wn ≤ 1. The simplest choicewould be to use a linear weighting function, given by

wn n

n n

e s

en (6)

where ns is the starting point and ne the end point of thedistorted portion. The linear weighting function is notoptimal, because the precision of an extrapolation deterio-rates with increasing length of the extrapolation. The mosteffective weighting function is formed so that the extrapo-lation closer to its starting point always has as large aweight as possible. The extreme case would be to use theforward extrapolation alone to the center of the damagedportion and then the backward extrapolation alone. In thiscase the weighting function wn would be a step function.However, due to different extrapolation errors, this couldlead to a discontinuity in the middle of the reconstructedsignal. The best weighting function can be found as acompromise between these two functions. The parametricgeneral weighting function is given by [11]

,

, >w

u

u

u

u

12

12

2

12 2

2

1

2

1

n

na

na

n

n

#_

_

i

i

Z

[

\

]]

]]

(7)

where

.un n

n n

e s

sn (8)

Both extreme cases can be obtained from Eq. (7) byselecting the parameter a 1 for linear weighting anda $ ∞ for step functions. The general weighting func-tions wn and 1 wn are illustrated in Fig. 2.

2 EXPERIMENTS

2.1 Objective Measurements2.1.1 Model Order

The theory of extrapolation stipulates that there shouldbe two impulse response coefficients for each frequency inthe signal, and if the amplitudes of the frequencies are notconstant, it requires additional coefficients to model thesignal properly. In a real-life case we do not know howmany frequencies there exist in the signal or the form oftheir amplitude envelopes. However, the optimal modelorder can be estimated experimentally by observing thequality of the extrapolated signal as a function of the num-ber of impulse response coefficients. This is achieved byestimating a known section of a given signal and compar-

ing the extrapolated estimate xn to the original signal xn.A conventional objective quality measure is the signal-

to-noise ratio (SNR). The SNR of the (forward) extrapo-lated signal is given by

2

logSNR

x x

x

10

n nn

W

nn

W

2

0

1

0

1

!

!

_ i

(9)

where W is the number of extrapolated samples. The termxn xn, where xn is the original signal, represents thenoise that is the error of the extrapolation. The SNR doesnot always have a high correlation with subjective listen-ing tests. The extrapolation can be considered as a func-tion approximation where the extrapolated signal is theapproximation of the original signal. By increasing themodel order a more detailed approximation of the desiredsignal is achieved. This learning process can be monitoredby observing the mean square error (MSE) between theestimate and the desired signal, given by

.MSEW

x x2

1 n n

n

W2

0

1

! _ i (10)

These measures give only the mathematical interpretationof the performance. However, the final “detector” is thehuman ear, which indicates that psychoacoustics shouldbe considered in the quality measure. It is known that fre-quency-to-place transformation occurs in the basilar mem-brane inside the hearing organism, suggesting that themeasurements should be accomplished in the frequencydomain rather than in the time domain. An objective meas-ure, based on subjective quantities, is the noise-to-maskratio (NMR), which indicates the occurrences of audiblenoise. The NMR is given by [12]

logNMRB T

CR

101

1

b

bk

k k

k

b

B

2

0

1

lb

hb

!! (11)


Fig. 2. Weighting functions wn and 1 wn for forward and back-ward extrapolations, respectively.


where Rk FFTxn xn, B is the number of criticalbands, Cb is the number of frequency components per crit-ical band, and klb and khb are lower and higher boundariesin each critical band. FFT denotes the fast Fourier trans-form. The calculation of the masking threshold Tb is pre-sented in [13]. The NMR measure has been found to havea high correlation with subjective tests [14]. A lower dBvalue corresponds to less audible noise; a negative NMRindicates that the noise is completely masked by the signaland thus is inaudible to the human auditory system.

A section of the audio signal with 1000 samples isextrapolated (forward only) several times by increasingthe length of the impulse response M and compared to theoriginal signal. The values of SNR, MSE, and NMR areplotted in Fig. 3 as a function of M. The length of theimpulse response is varied from 100 to 2000, and the num-ber N of previous samples used for the calculation of theimpulse responses was 3000. In Fig. 4 the 1000-sample-long extrapolated section is plotted in the same graph asthe original for three different impulse response lengths(M 100, M 300, M 1000). With 1000 impulseresponse coefficients the original signal is approximatedalmost perfectly.

2.1.2 Extrapolation LengthThe error in each extrapolated sample increases as the

extrapolation length increases. This phenomenon is illus-trated in Fig. 5, where SNR, MSE, and NMR are meas-ured for the last 500 (forward) extrapolated samples as afunction of the extrapolation length. Since the quality isvery high at the beginning of the extrapolated section, theaverage quality of the whole extrapolated section is muchbetter than the quality of the last 500 extrapolated samples.The quality values for the whole 5000-sample-long extra-polated section (used in Fig. 5) SNR 3.7 dB, MSE 0.0082, and NMR 4.7 dB. The quality of the extrap-olation can be improved significantly by extrapolatingfrom both directions. The quality values for the same5000-sample section with a weighted average (a 3) ofthe forward and backward extrapolated signals are SNR 10.6 dB, MSE 0.0018, and NMR 11.8 dB.

2.1.3 Removal of Impulsive NoiseThe proposed method for reconstructing missing or

damaged sections in the audio signal is applied in practiceto correct large scratches in signals recorded from dam-


Fig. 3. Audio signal section of 1000 samples is extrapolated several times by varying the number of impulse response coefficients(M 100 – 2000). Quality of extrapolation is monitored with three objective quality measures as a function of impulse response length.


aged vinyl recordings. The principle of the process is illus-trated in Fig. 6. Before reconstruction can be accom-plished, the location of the damaged samples must beknown. Methods for detecting impulsive errors in audiosignals are presented, for example, in [15]. The detectionis carried out by generating a detection signal with peaksindicating the error locations and using an adaptive thresh-old function for detecting the peaks. In Fig. 7 a largescratch resulting in about 700 damaged samples is recon-structed by the proposed method.

2.2 Subjective EvaluationsThree different audio samples were used for the listen-

ing tests. Signals were played from a CD, and high-quality headphones were used. In each track on the CD asound sample could be heard twice. In some cases the sec-ond sample contained an extrapolated section of variablelength. The listener had to decide whether the two sampleswere the same or different if some audible distortion couldbe perceived resulting from the extrapolation. These testswere carried out with 10 listeners.

The first sound sample contained a noisy bell soundrecorded from a synthesizer. Even though the sound char-

acteristics of the sound change relatively fast, the extrapo-lation performs well for long sections. However, the audi-ble difference results from the poor ability to extrapolaterandom noise, and a change in the background noiseamplitude can be perceived. The second sample was cho-sen to represent an extremely difficult situation for theextrapolation. It contained a stereo recording of a crashcymbal with a high degree of room ambience. Both chan-nels of the signal were extrapolated at the same location.For transparent extrapolation a high number of fading fre-quencies and the complex structure of the room ambiencerequire to be modeled with great detail. The third soundsample was a high-quality recording of a low key from anacoustic piano with a rich spectral harmonic structure.

Fig. 8 presents the results of the listening tests. The barsdenote the percentage of the 10 listeners who detected audi-ble differences in the sample with the extrapolated sectioncompared to the original sample. In the first sound sample(bell) none of the listeners detected any audible distortionwith the extrapolated section of 1000 samples (23 ms). Evenwith 7000 extrapolated samples (160 ms) 30% of the listen-ers did not detect any difference compared to the originalsample. This indicates that the resulting distortions are minor


Fig. 4. Audio signal section of 1000 samples is extrapolated three times with M 100, M 300, and M 1000. Extrapolated signalis plotted in same graph as original signal.



Fig. 6. Procedure for eliminating impulsive error in audio signal.

Fig. 5. Objective quality measures as a function of extrapolation length measured for last 500 extrapolated samples.


and barely audible. For the second sound sample (crashcymbal) only 200 samples could be extrapolated withoutanyone detecting a difference. However, 1400 samples couldbe extrapolated with 40% of the listeners not detecting anyaudible side effects. In the third sound sample (piano) evena 9000-sample section (200 ms) could be replaced by theextrapolated signal with 50% of the listeners not detecting it.

3 CONCLUSION

We have proposed a method for the correction of dis-turbances or gaps in audio signals. The algorithm can beapplied in practice to eliminate impulsive errors fromaudio signals recorded from damaged vinyl recordings orto recover data dropouts resulting in transmission


Fig. 8. Results of listening test. Bars denote percentage of listeners who detected audible difference in sample with a section replacedby extrapolated signal compared to original sample.

Fig. 7. Large click resulting in about 700 damaged samples is replaced by weighted average of forward and backward extrapolatedsignals.

THE AUTHORS


schemes. With the proposed method we can correctimpulsive errors up to thousands of samples in length fromCD-quality (16-bit, 44.1-kHz) audio signals without audi-ble distortion.

Based on information theory, information once lost can-not be recovered perfectly. But if there are some traces ofthe lost information in the preceding and the followingdata sections, the lost part can at least be partly recovered.In an audio signal, the significance of “partly” is to bedetermined by the human ear.

4 REFERENCES

[1] S. D. Cabrera and T. W. Parks, “Extrapolation andSpectral Estimation with Iterative Weighted Norm Modifi-cation,” IEEE Trans. Signal Process., vol. 39, pp. 842 –851 (1991).

[2] S. V. Vaseghi and P. J. W. Rayner, “Detection andSuppression of Impulsive Noise in Speech Communi-cation Systems,” IEE Proc. Commun., Speech, Vision, vol.137, pt. 1, pp. 38 – 46 (1990).

[3] A. J. E. M. Janse, R. N. J. Veldhuis, and L. B. Vries,“Adaptive Interpolation of Discrete-Time Signals that CanBe Modelled as Autoregressive Processes,” IEEE Trans.Acoust., Speech, Signal Process., vol. ASSP-34, pp. 317 –330 (1986).

[4] R. C. Maher, “A Method for Extrapolation ofMissing Digital Audio Data,” J. Audio Eng. Soc. (Engin-eering Reports), vol. 42, pp. 350 – 357 (1994 May).

[5] S. V. Vaseghi and R. Frayling-Cork, “Restoration of

Old Gramophone Recordings,” J. Audio Eng. Soc., vol. 40,pp. 791 – 801 (1992 Oct.).

[6] S. Godsill, P. Rayner, and O. Cappe, Digital AudioRestoration (Springer, London, 1998).

[7] I. Kauppinen, J. Kauppinen, and P. Saarinen, “AMethod for Long Extrapolation of Audio Signals,” J.Audio Eng. Soc., vol. 49, pp. 1167 – 1180 (2001 Dec.).

[8] S. Haykin, Nonlinear Methods of Spectral Analysis(Springer, Berlin, 1983).

[9] J. G. Proakis and D. G. Manolakis, Digital Signal Pro-cessing, 3rd ed. (Prentice-Hall, Englewood Cliffs, NJ, 1996).

[10] F. Keiler, D. Arbif, and U. Zölzer, “Efficient Linear Pre-diction for Digital Audio Effects,” in Proc. DAFX-00 (2000).

[11] P. Saarinen, “New Tools in Spectral Analysis,” PhDthesis, University of Turku, Finland (1996).

[12] D. E. Tsoukalas, J. N. Mourjopoulos, and C.Kokkinakis, “Speech Enhancement Based on AudibleNoise Suppression,” IEEE Trans. Speech Audio Process.,vol. 5, pp. 497 – 514 (1997 Nov.).

[13] J. D. Johnston, “Transform Coding of AudioSignals Using Perceptual Noise Criteria,” IEEE J. SelectedAreas in Commun., vol. 6, pp. 314 – 323 (1988 Feb.).

[14] J. Herre, E. Eberlein, H. Schott, and K. Branden-burg, “Advanced Audio Measurement System Using Psycho-acoustic Properties,” presented at the 92nd Convention ofthe Audio Engineering Society, J. Audio Eng. Soc.(Abstracts), vol. 40, p. 447 (1992 May), preprint 3321.

[15] I. Kauppinen, “Methods for Detecting ImpulsiveNoise in Speech and Audio Signals,” in Proc. DSP2002(2002 July).


Ismo Kauppinen was born in Oulu, Finland, in 1975.He studied physics at the University of Turku from whichhe received an M.S. degree in 1999, and where he is cur-rently a Ph.D. candidate near completion.

Mr. Kauppinen is currently working as a research assis-tant in the Department of Applied Physics at theUniversity of Turku. His research interests include com-puter music, digital sound analysis and resynthesis, audiorestoration, and auditory modeling.

Jyrki K. Kauppinen was born in Finland in 1944. Hereceived a B.A. degree in 1967, an M.Sc. degree inphysics in 1968, and a Ph.D. degree in 1975 from the

University of Oulu. He started his academic career atthe University of Oulu working in many positions fromassistant to professor. The National Research Councilof Canada appointed him a research fellow in 1980. Hewas elected a senior research fellow at the Academy ofFinland in 1981. In 1990 he was a visiting scientist atthe National Research Council of Canada and atKansas State University. At present he is a professor ofphysics at the University of Turku (since 1986), adocent in physics at the University of Oulu, and adocent in optical measurement technology at HelsinkiUniversity of Technology.

Dr. Kauppinen has published about 150 papers in inter-national scientific journals and has made about 130 con-

I. Kauppinen J. K. Kauppinen



ference presentations including about 40 invited lectures.He has written invited review articles in the Encyclopediaof Applied Physics, the Encyclopedia of Spectroscopy andSpectrometry, the Spectrometric Techniques, and theHandbook of Vibrational Spectroscopy. His paper dealingwith Fourier self-deconvolution has the highest citationnumber since 1975 in the Journal of Applied Spectro-scopy. In 2001 Kauppinen and Partanen published a bookFourier Transforms in Spectroscopy (Wiley-VCH). Hehas six patents and a few patents pending.

Dr. Kauppinen has been a member of the program andsteering committees in the International Conferences onFourier Transform Spectroscopy, a member of the work-ing group of IUPAC for Unified Wavenumber Standards,and a member of the Finnish Academy of Science andLetters. He was chair of the program committee and amember of the steering committee for the first Inter-national Conference of Advance Vibrational SpectroscopyICAVS-1 held in Turku. He is also a member of the pro-gram and steering committees for ICAVS-2, and is going

to be a member of the editorial board of Applied Spectro-scopy Reviews. Dr. Kauppinen received the InternationalBomem-Michelson Award in 1992 and the InnovationAward (the Foundation for New Technology) in 1999 fordeveloping the commercial FT-IR gas analyzer GASMETwith Temet Instruments Ltd.

His varied research interests include high-resolutionFourier transform spectroscopy, the development of high-resolution interferometers (resolution of 0.0004 cm1, thehighest in the world), infrared wavenumber standards,gauge measuring interferometer for the Finnish standard oflength, conventional rotation-vibration molecular spectro-scopy, low-resolution stationary interferometers (withoutmoving parts), the development of small very stable inter-ferometers for IR, NIR, VIS, and UV such as the Carousel-interferometer, the development of commercial, automaticgas analyzers such as GASMET, and the treatment ofexperimental data by various sophistical mathematicalmethods such as resolution enhancement using Fourierself-deconvolution, and the extrapolation of signals.

Call for Comment on REVISION of AES10-1991(r1997), AES recommended practicefor digital audio engineering—Format forthe user data channel of the AES digitalaudio interfaceThe browser URL is http://ftp.aessc.org/pub/aes10-R-xxxx.pdf. For direct FTP access, the site name isftp.aessc.org/pub/ and the file name is aes10-R-xxxx.pdf.The file is in Acrobat PDF format.

This document was developed by a writing group of theAudio Engineering Society Standards Committee (AESSC)and has been prepared for comment according to AESpolicies and procedures. It has been brought to the attentionof International Electrotechnical Commission TechnicalCommittee 100. Existing international standards relating tothe subject of this document were used and referencedthroughout its development.

Address comments by mail to the AESSC Secretariat,Audio Engineering Society, 60 E. 42nd St., New York, NY10165; or by e-mail to [email protected]. E-mail is pre-ferred. Only comments so addressed will be considered.Comments that suggest changes must include proposedwording. Comments must be restricted to this documentonly. Send comments to other documents separately.

This document will be reaffirmed by the AES after anyadverse comment received within three months of the publi-cation of this call on www.aes.org/standards/, 2002-07-12,has been resolved. All comments will be published on theWeb site.

Persons unable to obtain this draft document from theWeb site may request a copy from the secretariat at AudioEngineering Society Standards Committee, Draft CommentsDept., Woodlands, Goodwood Rise, Marlow, Bucks. SL73QE, UK.

Report of the SC-04-01 Working Group onAcoustics and Sound Source Modeling, ofthe SC-04 Subcommittee on Acousticsmeeting, held in conjunction with the AES

112th Convention in Munich, Germany2002-05-12Chair R. Campbell convened the meeting. The agenda andthe report from the previous meeting at the AES 110thConvention were approved as written.

Current development projects

AES-X05 Room and Source Simulators: Specificationand Evaluation of Computer Models for Design andAuralization; Recommendations for TransportableInput and Output FilesA PTD is on the FTP site as: X05-WG-PTD-010614.pdf.The chair reported that he has put the EASE compatible testroom posted by W. Ahnert into CATT but some additionaltesting remains to be done. The results of this will be posted.

AES-X70 Smoothing Digitally-Derived FrequencyResponse Data on a Fractional Octave BasisThe meeting decided to recommend, via this report, retirementof this project. If no objections are received within twoweeks of this posting, the chair will request the retirement.

AES-X83 Loudspeaker Polar Radiation MeasurementsSuitable for Room AcousticsThe discussion concentrated on two items, the proposal sub-mitted by B. I. Dalenback and another submitted by B. Olsen,direct impulse response, by means of a demonstration at theprevious meeting. See the report of the December meeting.

It was the consensus of the meeting that impulse re-sponses should be available as stand-alone WAV files forthose modeling programs that are prepared to accept themdirectly. The Dalenback proposal would have optionallyembedded them in the binary distribution.

After considerable discussion, it became apparent thatthese ideas can be merged whereby the IRs can be madeavailable on the distribution media as WAV files, andpointed to within the binary distribution block. In addition, apointer to one text header file can be used to furnish theextra non-radiation data needed to complete the WAV file-set information.


COMMITTEE NEWSAES STANDARDS

Information regarding Standards Committee activi-ties including meetings, structure, procedures, re-ports, and membership may be obtained viahttp://www.aes.org/standards/. For its publisheddocuments and reports, including this column, theAESSC is guided by International ElectrotechnicalCommission (IEC) style as described in the ISO-IECDirectives, Part 3. IEC style differs in some respectsfrom the style of the AES as used elsewhere in thisJournal. For current project schedules, see the pro-ject-status document on the Web site. AESSC docu-ment stages referenced are proposed task-groupdraft (PTD), proposed working-group draft (PWD),proposed call for comment (PCFC), and call forcomment (CFC).

This method allows both types of radiation data to be fur-nished to a modeling program. A loudspeaker manufacturerwould have the option of providing the IRs, or of convertingthe IRs to text format, including whatever post-processing isneeded to fit the desired data density. The resulting text filewould be made available to the user, or it can be convertedto a DLL-style binary data block and made available in thatfashion. Essentially, this adds one additional item at the frontend of the flow diagram shown in the Dalenback proposal.

The meeting felt that the following data should be madeavailable:

a) impulse response files together with a descriptive textheader;

b) text-only data formatted in a way to allow the con-struction of radiation balloons;

c) a binary data block containing all of the radiation infor-mation which, depending upon the format required by themodeling program, may contain embedded IRs or it mayreference IRs stored elsewhere on the distribution media.

It also felt that the document should include:a) transformation of IRs into text-based radiation data

either as IRs or a proprietary data acquisition system;b) transformation of text data to binary data in preparation

of creating the binary data block;c) merging of binary radiation data with other data (or

pointers to IRs) and final formatting for modeling programdirect binary input compatibility.

These items, including an example of a flow chart for theinformation, are included in proposed task-group draft X83-ptd-rc-020517.pdf on the FTP site.

The meeting recognized that for many applications, IRdistribution is not necessary, and the route through text, ortext followed by a DLL, will be sufficient to provide mean-ingful room acoustic modeling data. In addition, some man-ufacturers may be reluctant to furnish IRs, and may thereforeuse the alternate route such as the Dalenback proposal. Notethat the WAV file data set has been previously discussedand one possible file structure identified, but not yet incor-porated into a PTD.

Some examples of current use were pointed out bymembers:

— The EASE program can accept manufacturer’s IRs di-rectly and produce radiation pattern data for use internally tothe program. It can also work with text radiation balloon data.

— The CATT program can accept text radiation balloondata and also a proprietary DLL-based binary data blockcreated from manufacturer’s measured radiation data.

— Many small loudspeakers typically used for wall-mounting or ceiling mounting can be adequately modeledusing rather low-density radiation balloon text data.

— Musical instrument directivity, a critical issue for ac-curate auralization, is usually given in sparse text balloonformat.

The chair will attempt to merge these ideas into a singledraft document and post it by 2002-09-01.

During the discussion, mention was made of a mea-suring system using a simple file naming convention forIRs. For reference, the URL is http://www.anselm-

goertz.de/Page10383/Monkey_Forest_dt/monkey_forest_dt.html.

AES-X108 Measurement of the Acoustical andElectroacoustic Characteristics of Personal ComputersD. Queen explained that SC-04-01 was assigned this task as anew project because the expertise for it did not reside in SC-02-01 to which the review project, AES-6id-R, is assigned.

He noted that the intent of AES-6id is to guide thecomputer manufacturer, who may have limited expertise in-house, in making relatively simple sets of measurements toquantify the audio quality of personal computers. Theacoustic procedures in the PTD on SC-0401-D FTP site, 6ID-R-A1-PTD-DQ-011117.pdf will represent an improvementover what is done now, even if they are not up to laboratorypractice for loudspeakers, microphones, and product noise.

Members suggested that the document emphasize thatmeasurements are to be made on one channel at a time.

Several members noted that, contrary to the draft, manu-facturers of test equipment do not provide guidelines for theuse of their products, so that the minimum acoustical re-quirements of the room including dimensions, positions, andbackground noise must be included.

The group also recommended that test signals be providedon the AESSC Web site to allow real-time analyzer mea-surements.

The discussion also provided a standard means to positionlaptops with respect to the test microphone and sound source.

After considerable discussion, the group consensus wasthat distortion measurements should not be included. Queennoted, however, that these measurements are included incurrent industry documents, so AES-6id should explain whythey are misleading.

Queen will revise the PTD according to the discussion.Members urged that WG members try measuring their

own equipment as an indicator of potential technicalproblems.

AES-X122 Loudspeaker Radiation and AcousticalSurface Data Measurements: How They Apply to UsageEnvironmentsThe chair noted that this project was initiated at theAmsterdam meeting and that conceptually, this work treatsspecial wall surfaces such as diffusers (both active andpassive) as secondary sound sources. Thus the same ra-diation data density as used in primary sources under dis-cussion under project AES-X83 might apply for purposes ofroom acoustic modeling.

The working group decided to request that the project besuspended until the work on AES-X83 and AES-X05 isfurther advanced.

New projectsNo project requests were received or introduced.

New businessThere was no new business.

The next meeting is scheduled to be held in conjunctionwith the AES 113th Convention in Los Angeles, CA, US.


AES STANDARDSCOMMITTEE NEWS


this issue. See page 610 for a complete exhibitor list and page614 for a preview of exhibitor products.

A full program of standards meetings is scheduled prior toand during the convention. Check the AES Standards Com-mittee page at www.aes.org/standards for the complete listof times and locations. The AES Technical Council has anambitious schedule of technical committee meetingsthroughout the convention; see www.aes.org/technical.

SPECIAL EVENTSThe Platinum Producers Series—panels of industry insidersdiscussing their craft—will be presented on Sunday andMonday. Veteran radio actors will stage a 75th anniversaryperformance of the Lux Radio Theater production of TheJazz Singer on Sunday evening. On Sunday delegates canhear one of the great innovators of multichannel sound dur-ing “An Afternoon with Tom Holman.” Saturday throughMonday evenings delegates can meet colleagues and relaxwith a cool drink at the Songwriters’ Showcase in the SouthLobby. Graham Blyth will present a concert on the newDobson organ on Tuesday morning during a tour of the re-cently completed Cathedral of Our Lady of the Angels. Thehugely popular When Vinyl Ruled exhibit, produced by theHistorical Committee, will run throughout the convention.

AUDIO EDUCATION AND STUDENT PROGRAMSThe 113th education events will include Student DelegateAssemblies, a Poster Session, the Education Fair, the Edu-cation Forum, the Recording Competition, and two one-on-one Mentoring Sessions. Also, two workshops—Stereo andSurround Microphone Techniques and Mixing and Master-ing in Multichannel Surround—will be produced by theAES Education Committee.

Whether you are seeking the latest leading-edge informationto be presented in the technical papers and workshops or thelatest equipment advancements to be shown by exhibitors, youwill find numerous opportunities to satisfy your interests in au-dio at the AES 113th Convention. Join your colleagues fromaround the world at this global audio extravaganza.Editor’s Note: For late-breaking convention updates and oth-er Society news, visit www.aes.org.

Come to the City of Angels this fall when audioenthusiasts from around the world gather for theAES 113th Convention. An exciting lineup oftechnical papers, workshops, and products hasbeen put together by Convention Chair Floyd

Toole and his creative committee. The official opening cere-monies on Saturday morning at the Los Angeles ConventionCenter will be highlighted by the keynote address of standardsvisionary Leonardo Chiariglione, the “father of MPEG.”Chiariglione has in the past expressed some unexpected opin-ions for a global standards guru, saying that “Bill Gates hasbeen a benefactor of mankind.” His keynote address promisesto be thought-provoking and entertaining.

THE RICHARD C. HEYSER MEMORIAL LECTUREOn Monday evening 113th delegates will have an opportunityto hear Jim West. His pioneering research on charge storageand transport in polymers (the electrical analogy of a perma-nent magnet) led to the development of electret transducersfor sound recording and voice communication. Almost 90%of all microphones built today are based on the principlesfirst published by West in the early 1960s. He holds 47 U.S.and over 200 foreign patents on various microphones andtechniques for making polymer electrets. A Bell Laborato-ries Fellow, he recently retired from Lucent Technologiesand is now a research scientist in the Multimedia Technolo-gies Research Lab of Avaya.

THE TECHNICAL PROGRAMPapers Cochairs Eric Benjamin and John Strawn have assem-bled 14 sessions of 78 papers by researchers from around theworld. Session topics will include Transducers, Signal Pro-cessing, Room Acoustics and Sound Reinforcement, Multichan-nel, Low Bit-Rate Coding, High-Resolution Audio, Recordingand Reproduction, Audio Networking and Automotive Audio,and Psychoacoustics. Workshops Chair Marshall Buck hasplanned 15 in-depth workshops looking at the entire spectrumof audio technologies. Also on tap are eight technical tours toLA audio facilities. A complete list of papers, workshops, andtechnical tours can be found at www.aes.org. Tentative datesand times appear on the Convention Calendar on page 608 of

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AES 113th

ConventionLeonardoChiariglione,keynote speaker

Jim West, Heyser lecturer

2002 October 5–8Los Angeles Convention Center

Los Angeles, California,USA

Mono

Multichannel

Stereo

• Home Theater/Entertainment

• Wireless + Portable

• Telecom + Voice

• Gaming

• Internet + Broadcast

Technologies. Product Applications

World Wide Partners

• Circle Surround II

• FOCUS

• SRS 3D

• SRS Headphone

• TruBass

• TruSurround XT

• VIP

• WOW

The Future of Audio. Technical information and online demos at www.srslabs.com2002 SRS Labs, Inc. All rights reserved. The SRS logo is a registered trademark of SRS Labs, Inc.C

Aiwa, AKM, Analog Devices, Broadcom, Cirrus Logic, ESS, Fujitsu, Funai,

Hitachi, Hughes Network Systems, Kenwood, Marantz, Microsoft,

Mitsubishi, Motorola, NJRC, Olympus, Philips, Pioneer, RCA, Samsung,

Sanyo, Sherwood, Sony, STMicroelectronics, Texas Instruments, Toshiba

SRS Labs is a recognized leader in developing customized audio solutions for any application. Its

diverse portfolio of proprietary technologies includes mono and stereo enhancement, voice processing,

multichannel audio, headphones, and speaker design. • With over seventy patents, established platform

partnerships with analog and digital implementations, and hardware or software solutions, SRS Labs is

the perfect partner for companies reliant upon audio performance.

AAardvark

ACO Pacific, Inc., p. 614

Acoustic Systems, p. 614

Acoustical Solutions, Inc., p. 614

A.D.A.M. Audio GmbH, p. 614

ADK Microphones

AEA, p. 614

AEQ, S.A., p. 614

Akai Musical Instrument Corp., p. 614

AKG Acoustics, US, p. 614

AKM Semiconductor, p. 616

Alcorn McBride, Inc., p. 616

Alesis Distribution LLC

Allen & Heath, p. 616

Altermedia, Inc., p. 616

Amek

Ametron Audio/Video, p. 616

AMS Neve PLC

Analog Devices, Inc., p. 616

Apogee Electronics, Inc.

Applied Microphone Technology, p. 616

Arboretum Systems, Inc., p. 616

ART-Applied Research & Technology

ATC Loudspeaker Technology

The ATI Group, p. 616

ATR Service Co., p. 616

Audio Accessories, Inc., p. 616

Audio Engineering Associates, p. 616

Audio Precision, Inc. Audio-Technica U.S., Inc.,

p. 616

AudioControl IndustrialAuralex AcousticsAvalon Design, Inc., p. 616

BBag End LoudspeakersBaltic Latvian Universal Electronics - “B.L.U.E.” Belden Electronics DivisionBenchmark Media Systems, Inc., p. 617

Berklee College of Music, p. 617

BIAS (Berkley Integrated Audio Software) Brauner/Transamerica AudioBrüel & Kjær North America, p. 617

Bryston Ltd., p. 617

BSS AudioC

Cable Factory, p. 617

Cadac Electronics PLC, p. 617

Cakewalk Calrec Audio Ltd.

CB Electronics, p. 617 CEDAR Audio Ltd.

Chevin Research Ltd., p. 617

Cirrus Logic Inc. Cliff Electronic Components, Inc., p. 617

Club Systems International, p. 617

Coles/Audio Engineering Associates, p. 617

Community Professional Loudspeakers, Inc.Convention TV, p. 617

Cooper Sound Systems, Inc.,p. 617

Countryman Associates, Inc.Crane Song, Ltd.Crest Audio, p. 618

Crown International, p. 618

Cycling ’74, p. 618

D D.A.S. Audio S.A., p. 618 D.A.S. Audio of America, p. 618

Dan Dugan Sound DesignData Linked Productsdbx Professional Products, p. 618

dCS Ltd.


Sustaining Member of the Audio Engineering Society

Advertiser in this issue

Following is the list of exhibitors available at press time.

113th EXHIBITORSLLLLoooossss AAAAnnnnggggeeeelllleeeessss,,,, CCCCaaaallll iiiiffffoooorrrrnnnniiiiaaaa

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Demeter Amplification, p. 618

Denon Electronics, p. 618 Digidesign

Digidesign Development Partners

DigigramDigital Music TechnologiesDigital Theater Systems, Inc.Disc Makers, p. 618

DJ Times, p. 618

DK Audio A/S Dolby Laboratories, Inc., p. 618

Doremi Labs, Inc.Dorrough Electronics, p. 618

Drawmer (USA) / Transamerica Audio Group, Inc.

DTS, p. 618

D.W. Fearn E

Eastern Acoustic Works, Inc., p. 618

Electronic Musician Magazine, p. 620

Electro-Voice, p. 620

EMTEC Multimedia, Inc., p. 620

ETA SystemsEuphonix, Inc.Eventide Inc.Expression Center for New Media

FFairlight USAFAR - Fundamental Acoustic

Research Fostex America

Fraunhofer Institute for Integrated Circuits, p. 620

Furman Sound

GGefen Systems, Inc., p. 620

GenelecGeoffrey Daking & Co., Inc., p. 620

Gepco International, Inc., p. 620

Gibson Labs, p. 620

Glyph Technologies (USA)GML: George Massenburg Labs LLC, p. 620

Gold Line/TEF, p. 620

Gordon Instruments, p. 620

Gotham Audio Cable, p. 620

Grace DesignGreat River Electronics Inc., p. 620

Group One Ltd.

HH.E.A.R. (Hearing Education & Awareness for Rockers), p. 620

HHB Communications USA, Inc., p. 620

Hosa Technology, Inc. House Ear Research Institute, p. 621

IiBiquity Digital Corporation, p. 621

ILIO Entertainments, p. 621

IMAS Publishing/Audio Media/Pro Audio Review, p. 621

Independent Audio Innova SON SA, p. 621

International DJ Expo/The Club Show, p. 621

iZ Technology Corporation, p. 621

J JBL Professional

Jensen Transformers

The John Hardy Company

Josephson Engineering

RF Magnetic Sciences

KKlark Teknik, p. 621

Klippel GmbH, p. 621

KRK Systems, LLC, p. 621

Kurzweil Music SystemsL

L-Acoustics US, p. 621

Lectrosonics, Inc., p. 621

Lexicon, Inc., p. 622

Linn Products Ltd. Listen, Inc., p. 622

Logitek Electronic SystemsLundahl Transformers ABLynx Studio Technology, Inc., p. 622

MMackie DesignsMAD LabsMAGMA, p. 622

Manley Labs, p. 622

Marquette Audio Labs, p. 622

Marshall Electronics, Inc. (Mogami Cables)Marshall Electronics, Inc. (MXL Microphones)

Martin Audio

Martinsound, Inc.MBHO Microphones, p. 622

McCauley Sound, Inc.Mercury Recording Equipment Co., p. 622

Merging TechnologiesMetric Halo Distribution, Inc.Meyer Sound, p. 622

Microboards Technology, LLC, p. 622

Midas, p. 622

Midiman/M. Audio Inc. Millenia Music & Media Systems, p. 622

Mix Magazine, p. 623Motorola, Inc.


1111 1111 3333tttt hhhh CCCCoooonnnnvvvveeeennnntttt iiii oooonnnnEXHIBITORS

mSoft Inc., p. 623

The Museum of Sound Recording, p. 623

The Music & Sound Retailer, p. 623

Music Maker Publications/ Recording MagazineMytek Digital, p. 623

NNagra USANational Academy of Recording Arts and Sciences, Inc. (Recording Academy), p. 623

Native Instruments USA, p. 624 Neumann/USA, p. 624 Neutrik USA, Inc., p. 624 Neutrik Test Instruments AG (NTI)

New Transducers Ltd. NHT Pro, p. 624

Noren Products, Inc. Norris-Whitney Communications

OOpticom GmbH, p. 624

Otari Corporation, p. 624

PPeavey Electronics Corp. Pelonis Sound & Acoustics, Inc., p. 624

Pendulum Audio, Inc. Penn Fabrication, Inc.Penny & Giles Controls Inc., p. 624

Pilchner Schoustal International Inc., p. 624

Plus24 PMC Monitor Company, p. 624

PMI Audio Group, p. 624

Post Magazine, AdvanStar Communications Inc., p. 624

Powerphysics Precision Laboratories

PreSonus Audio Electronics Primedia, p. 624

Prism Media Products, p. 625

Professional Audio Design, Inc.,p. 625

PWM Systems, p. 625

QQuested Monitoring Systems, p. 625

QSC Audio Products Inc.

RRADIAN Audio Engineering, Inc., p. 625

Rane Corporation, p. 625

RCS, p. 625

Renkus-Heinz, Inc., p. 625

Resolution, p. 625

RODE Microphones, p. 625

Rohde & Schwarz GmbH & Co. KG, p. 625

Roland CorporationRolls CorporationRoyer Labs RTS, p. 625

SSabine, Inc., p. 625

Sabra-som Ltd. (K-IV Enterprises)

SADiE (Studio Audio & Video Ltd.)SAE Institute of TechnologySchoeps/Redding Audio, Inc., p. 626

SE Electronics, p. 626 Sennheiser Electronic Corp.,

p. 626

Sequerra Audio Labs LLCShep & Associates, p. 626

Shure IncorporatedSLS Loudspeakers

Solid State Logic Ltd.SONY Electronics, Inc.Sound & Communications, p. 626

Sound & Video Contractor Magazine, p. 626

Sound Devices, LLCSound Ideas

Sound on Sound, p. 626 Soundcraft

Soundelux Microphones, p. 626

Soundfield Research/ Transamerica Audio Group

SPARS, p. 626

SRS Labs, Inc., p. 626

Steinberg North America, p. 626 STUDER North America Inc.,

p. 627

Studio Network Solutions, p. 627

Studio Technologies, Inc.Summit Audio Inc., p. 627

Sunrise E. & E., Inc., p. 627

Switchcraft Inc., p. 627

Symetrix, Inc. Syntrillium Software Corporation, p. 627

Sysid Labs, p. 627

T Tannoy TASCAM, p. 627

TC Electronic Inc.TECA, p. 627

Telex Communications, p. 627

TerraSonde (USA)Testa Communications, p. 627

Texas Instruments THAT Corporation

Trian ElectronicsU

United Entertainment Media, a CMP Company, p. 628

Universal Audio, p. 628

VVidiPax, p. 628

Vienna Symphonic Library GmbH, p. 628

WWave Arts, Inc., p. 628

Wave Distribution, p. 628

Wave Space, Inc., p. 628

Waves Ltd., p. 628

West Penn Wire/CDT, p. 628

Westlake Audio, p. 628

Whirlwind WhisperRoom, Inc., p. 628

Wireworks Corporation, p. 628

Wohler Technologies, p. 628

World Link Digital, p. 628

Y Yamaha Corporation of America

Yamaha Corp. - mLAN Licensing Office, p. 628

ZZ-Systems, Inc.Zaxcom Audio

EXHIBIT HOURS

Saturday, October 5 ...................................................12:00 noon–6:00 pm

Sunday, October 6 ......................................................10:00 am–6:00 pm

Monday, October 7 ......................................................10:00 am–6:00 pm

Tuesday, October 8 ......................................................10:00 am–4:00 pm

Exhibit Previews

A E S S U S TA I N I N G M E M B E R

ACO PACIFIC, INC. (Belmont, CA,USA) will introduce the 7052SM andMK224SM packages which providemeasurement transparency, stability,and ICP™ accelerometer compatibility.The company will also feature theACOustic Interface™ and Simple In-tensity™ systems, Very Random™white/pink-noise generators, 94/124dBSPL calibrators, and ACOpell™weatherized windscreens.

ACOUSTIC SYSTEMS (Austin, TX,USA) manufactures and installs acous-tical products for recording arts, broad-cast, and other special applications. Thefirm focuses on preengineered studiosmanufactured to customer’s specifica-tions in consultation with national salesrepresentatives at NCC New York.

ACOUSTICAL SOLUTIONS, INC.(Richmond, VA, USA) offers a completeline of sound control and noise reductionproducts for use in all types of applica-tions including recording studios, broad-

cast facilities, distance learning class-rooms, architectural acoustics, houses ofworship, theaters, auditoriums, gymnasi-ums, home theaters, residential, tele-conferencing and videoconferencing environments, as well as all types of in-dustrial noise control.

A.D.A.M. AUDIO GMBH (Berlin,Germany) will show a wide range ofactive (powered) and passive studiomonitors. The mid-range and tweeterunits feature the Air Motion trans-former principle.

AEA (Pasadena, CA, USA) will showthe new AEA R78 vocal microphone.As with its R44 replica microphone,the company has maintained the in-tegrity established by RCA in the1930s by combining state-of-the-arttechnology and handcrafted workman-ship. AEA products are known for

their smoothness, forgiving nature, andtonal balance. For further product in-formation see also Audio EngineeringAssociates, p. 616.

AEQ, S.A. (Leganés, Spain) will fea-ture the BC 2000D digital console,which was conceived and designed withmore than twenty years of experience inthe construction of mixing consoles; theE@sy Family, including SWINGportable and EAGLE and COURSE sta-tionary audio codecs, communicationsunits for ISDN and POTS, IMPACTdigital audio router, and CADDYAD/DA converter; and the SYSTEL6000 multiplexer software for ISDNlines, which provide multiconferencingand on-air talk show control.

AKAI MUSICAL INSTRUMENTCORP. (Fort Worth, TX, USA) willshow the DPS24, an affordable, pro-fessional quality, 24-track recorderwith a feature-rich professional digitalmixer; and the MPC4000, the latest inthe MPC series. The company is aworldwide leader in audio equipmentfor the musical instrument, project stu-dio, professional, and postproductionmarkets.


AKG ACOUSTICS, US (Nashville,TN, USA) will feature microphonesand headphones used in a diverse arrayof applications, including music,


EXHIBIT PREVIEWS

recording, permanent install, broadcast,and new technologies.


AKM SEMICONDUCTOR (San Jose,CA, USA) designs and manufacturesmixed-signal audio ICs for professionaland consumer markets. Products in-clude S/PDIF transmitters and re-ceivers; 192-kHz audio ADCs, DACs,and codecs; and chips with integratedPLLs, amplifiers, and preamplifiers.The company also provides world-classsupport and custom design assistance.

ALCORN MCBRIDE, INC. (Orlando,FL, USA) designs and manufacturesdigital audio, video, lighting, and showcontrol products. The firm also pro-vides custom-design/build consultingand manufacturing services. Productsinclude MP3 machines, 8TRAXX, bin-loop, DVM/2, and DVM/HD.

ALLEN & HEATH (Sandy, UT, USA)is a leader in the live mixing consoleindustry. The firm’s professional con-soles—the MixWizard, the Xone se-ries, and the ML series—can accom-modate any application and level ofuser’s needs.

ALTERMEDIA, INC. (Burbank, CA,USA) will exhibit Studio Suite, a leadingstudio management software that handlesscheduling, project management, con-tacts and communications, invoices,tape/disk library and labels, equipmentand media inventories, recall sheets, me-dia asset management, and more. Thesoftware is networkable across Macin-tosh and Windows platforms and ispowerful enough for multiroom facilitieswhile priced for the project studio.

AMETRON AUDIO/VIDEO (Holly-wood, CA, USA) rents, sells, installs,and repairs professional audio andvideo equipment. The company stocksthousands of cables, connectors, micro-phones, amplifiers, mixers, loudspeak-ers, major formats of recorders/playersand recording media. It also has in-house soundproof edit suites, a fullyequipped screening room, and climate-controlled tape vault storage facilities.

ANALOG DEVICES, INC. (Nor-wood, MA, USA) produces high-per-

formance precision audio signal pro-cessing converters, digital signal pro-cessors, and software that deliverrecording studio quality audio to a widevariety of professional, home, automo-tive, portable, and handheld applica-tions, expanding the ability of artistsand recording engineers to add effects,realism, and clarity to their work. Witha wide choice of industry-standard for-mats, the company helps bring therecording studio and movie theater lis-tening experience to the mass market.

APPLIED MICROPHONE TECH-NOLOGY (Berkeley Heights, NJ,USA) designs microphones for wood-wind, brass, string, percussion, andfretted instruments. Each microphone isdesigned to produce the natural soundof the instrument.

ARBORETUM SYSTEMS, INC.(Pacifica, CA, USA) manufactures, dis-tributes, and licenses audio software so-lutions for music recording, film/videopostproduction, multimedia, broadcastand audio restoration for the profes-sional and consumer markets world-wide. Product lines showcased will include Montage, for multimedia au-thoring; Hyperprism, for sound effectsprocessing; Ray Gun and Ionizer, fornoise reduction and sound clean-up;and Realizer and Realizer Pro, for au-dio streaming.

THE ATI GROUP (Jessup, MD, USA)manufactures three product lines of highquality professional audio equipment:ATI Paragon II monitor and FOH con-soles, API Legacy recording consolesand a large selection of rack mountproducts, and Automix by Uptownmoving fader automation for analogmixing consoles. The ATI Group is theUSA distributor for Audient gear.

ATR SERVICE CO. (York, PA, USA)will demonstrate its new ARIA refer-ence range of class-A tape recorder

electronics that provides quantitativeand qualitative audio improvements toexisting analog tape transports. Thefirm will also demonstrate the newATR-108C 2-in, 8-track unit and theAmpex ATR102 1-in and 1⁄2-in remanu-factured recorders and accessories.

AUDIO ACCESSORIES, INC. (Mar-low, NH, USA) will display audio jackpanels and jacks (1⁄4-in long frame andTT/mini), prewired audio patchbays topunch-down terminals and multipinconnectors, audio patch cords and cordholders, interconnect cables, and otherpatching accessories.

AUDIO ENGINEERING ASSOCI-ATES (Pasadena, CA, USA) manufac-tures tall stands and booms for locationand studio applications, decca trees andstereo microphone arrays, stereo phasedisplays, and MS stereo width con-trollers. For further product informationsee also AEA, p. 614.


AUDIO-TECHNICA U.S., INC.(Stow, OH, USA) will display a varietyof professional microphones and relatedproducts, including the Artist Elite™handheld condenser and dynamic mi-crophones; the 40 Series premium lineof studio microphones specially engi-neered for precise performance; and theprofessional and affordable 30 Seriescondenser microphones.

AVALON DESIGN, INC. (SanClemente, CA, USA) will exhibit theVt-737sp class-A mono vacuum tubemicrophone/preamplifier/compressor/equalizer, Vt-747sp class-A stereo vac-uum tube/discrete compressor/


equalizer, U5 class-A discrete DI boxand instrument preamplifier, M5 class-A mono discrete microphone preampli-fier, AD2022 class-A dual mono dis-crete microphone preamplifier,AD2044 class-A dual mono/stereoopto-compressor, AD2055 class-A dualmono music equalizer, and AD2077class-A dual mono mastering equalizer.

BENCHMARK MEDIA SYSTEMS,INC. (Syracuse, NY, USA) will exhibitstate-of-the-art digital and analog audioequipment. On display will be the latestin no-compromise 24-bit digital con-version, such as the jitter immune 24-bit/96-kHz DAC-1 two-channel D/Aconverter with UltraLock Technolo-gy™. The firm also offers a wide rangeof products including A/D and D/Aconverters, distribution amplifiers, mi-crophone-preamplifiers, meter systems,and interface amplifiers.

BERKLEE COLLEGE OF MUSIC(Boston, MA, USA) is one of theworld’s largest independent music col-leges and premier institutions for thestudy of contemporary music, offeringcourses toward a fully accredited four-year baccalaureate degree or diploma.

BRÜEL & KJÆR NORTH AMERI-CA (Norcross, GA, USA), a leadingmanufacturer of test and measurementinstrumentation and software for acous-tics and audio application, will exhibitmeasurement microphones and couplersfor transducer measurement and design;Ometron scanning laser systems for non-contact measurements of loudspeakercone motion; sound-level meters androom acoustics software (Dirac) for char-acterizing room acoustics; and Odeonsoftware for modeling performancespaces and sound system coverage.

BRYSTON LTD. (Peterborough, On-tario, Canada) is a well-known builderof high-quality audio equipment includ-ing power amplifiers, preamplifiers,crossover networks, 70-V products, andsurround processors. Bryston is the ex-clusive North American distributor forthe PMC professional monitor systems.

CABLE FACTORY (Burnaby, BritishColumbia, Canada) manufactures theLive Link standard and custom snakes,

custom studio patchbay wiring, and DI-Pro direct box; and provides in-housecustom metal work. The firm is the ex-clusive North American distributor ofthe Lundahl Audio transformers, theGotham Audio cables, all types of tour-ing and studio-quality cabling, and theLive Link touring cables.


CADAC ELECTRONICS PLC (Lu-ton, Beds., UK) offers a comprehensivelineup of mixing consoles for sound re-inforcement and location recording ap-plications. Equipment on display willinclude the R-type lightweight touringconsole, J-type and F-type live produc-tion consoles, M-type monitor boardSound Automation Manager for Win-dows®, and Plus 5.1 C-type locationrecording console for surround soundrecording and monitoring.

CB ELECTRONICS (Charvil,Berks., UK), specialist in time code,biphase, and serial control for video,film and audio postproduction, will in-troduce the P2 DVD, which brings P 9control to DVD playback. The SR series of 9-pin serial controllers areoptimized for audio postproduction.The firm’s VS-1 video streamer is aninternational standard.

CHEVIN RESEARCH LTD. (OldLyme, CT, USA) was established in1989 in Otley, West Yorkshire, UK. Ini-tially the company designed equipmentfor the laboratory/scientific market,where it still remains active, having de-veloped the compact and lightweightChevin power supply.

CLIFF ELECTRONIC COMPO-NENTS, INC. (Benicia, CA, USA)designs and manufactures audio con-nectors and accessories. Products in-clude: a full line of 1⁄4-in jack sockets,plugs, XLR connectors, touchproof ter-minal binding posts, Euro-US-UKcordsets, digital processor boards,knobs, Optifade, and a full line of

phono and DIN connectors. The firm isthe exclusive worldwide distributor forAlan Parson’s Soundcheck-2 Test CDand Qualkit Pro PC Test software andhas been a supplier to OEM manufac-turers since 1962.

CLUB SYSTEMS INTERNATION-AL (Port Washington, NY, USA) willfeature Club Systems International, atrade publication covering professionalaudio, video, lighting, and security sys-tems in nightclubs, dance clubs, livemusic performance venues, and enter-tainment centers. Its audience is clubowners, operators, managers, installers,contractors, and disc jockeys.

COLES/AUDIO ENGINEERING AS-SOCIATES (Pasadena, CA, USA) willintroduce the new Coles 4040 studio rib-bon microphone. Also shown will be theBBC-developed 4038 studio ribbon mi-crophone and the 4104B “no voicebooth needed” lip microphone. AEA’s4038 stereo microphone template forBlumlein and near-coincident configura-tions will also be demonstrated. Thefirm also provides reribboning and cus-tom accessories and has been a distribu-tor in North America since 1984.

CONVENTION TV (Port Washington,NY, USA) is a leader in trade show newsfor the music, sound, lighting, and A/Vindustries. Convention TV and conven-tionTV.net ensures that a company’smessage is both seen and heard by moretrade show attendees and thousands ofprospects who missed the show.

COOPER SOUND SYSTEMS, INC.(San Luis Obispo, CA, USA) designs


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and manufactures the CS104 andCS208 portable audio mixers. The firmwill exhibit the new CS104-4T directout option: four outputs independent ofmain outputs. New optional features forthe CS208 will be shown including fourbalanced outputs for use with eight-trackrecorders and internal A/D converters.All new options are retrofittable.

CREST AUDIO (Fair Lawn, NJ,USA) designs and manufactures audioamplifiers, NexSys control systems,and live mixing consoles. Products in-clude the PRO and CA professionaltouring amplifiers, the CKV/CKS/CKipower processing amplifiers, the LT/STSeries of lightweight amplifiers, andthe V12, X-Series, and X-Rack Seriesconsoles. Also shown will be productsfrom the Crest Performance Range in-cluding loudspeakers, equalizers, andCPx amplifiers.

CROWN INTERNATIONAL (Elkhart,IN, USA) manufactures power ampli-fiers, microphones, and systems controlfor the professional audio industry.

CYCLING ’74 (San Francisco, CA,USA) develops, distributes, and sup-ports Macintosh OS and Windowsproducts for musicians using pro-grammable music, audio, and multime-dia software. New products being fea-tured include pluggo 3 for RTAS, MAS,and VST host applications and the radi-aL live performance audio application,as well as Max/MSP, pluggo, radiaL,and M.


D.A.S. AUDIO, S.A. (Valencia,Spain) will display the new Compact 2self-powered loudspeaker system, afour-way, triamplified system thatcomprises the Compact 2, mid-highsystem, and the Compact 18 Sub, low-frequency system. It is configured as athree-way system that has a usable op-erating range from 60 Hz to 18 kHz,which optimizes performance and reli-ability in sound reinforcement applica-tions requiring high sound pressurelevels and exceptional sound quality.


D.A.S. AUDIO OF AMERICA (OldLyme, CT, USA) manufactures loud-

speaker systems and transducer com-ponents, which are supplied to othersystems builders throughout the world,as well as power amplifiers, electronicsignal processors, and accessories thataddress the gamut of sound reinforce-ment applications.

DBX PROFESSIONAL PROD-UCTS (Sandy, UT, USA), a leader inthe professional audio industry for over30 years, offers a full spectrum of pro-fessional audio solutions, from com-pressors and equalizers to loudspeakermanagement systems.

DEMETER AMPLIFICATION (VanNuys, CA, USA) manufacturers of am-plifiers and signal processing equip-ment will exhibit Classic SeriesVTMP-2C microphone preamplifier;HXM-1 microphone preamplifier;HXC-1 optical tube compressor;VTHF-300M 300-watt mono blockpower amplifier; VTDB-2B mono tubedirect box with Jensen output trans-former; STDB-1 stereo tube direct boxwith Jensen output transformers; HDI-1stereo tube direct/line driver; RV-1 RealReverb; SSC-ILC silent speaker cham-ber with Celestion Vintage 30 60-wattspeaker.

DENON ELECTRONICS (PineBrook, NJ, USA) is an industry leaderin digital, surround sound, broadcast,DJ, installer, and analog audio technol-ogy for over 100 years. Products shownwill include CD and MD player/recorders, DVD players, dual and sin-gle cassette decks, HDD/solid-state au-dio/video players, A/V surround soundamplifiers, paging amplifiers, mixers,and headphones.

DISC MAKERS (Pennsauken, NJ,USA) is a leading independent CDmanufacturer offering complete CD,cassette, and 12-in vinyl packages. Thecompany also provides helpful guides,newsletters, and DIY resources for theindependent musician.

DJ TIMES (Port Washington, NY,USA) will feature DJ Times, an indus-try bible for the mobile and club DJ.As club music culture has evolved intopop music culture, the publication haschampioned the DJ. As the market

continues to expand, this periodical of-fers a cost-effective vehicle for reach-ing DJs.


DOLBY LABORATORIES, INC.(San Francisco, CA, USA) will demon-strate the new DP564 multichannel au-dio decoder, the next-generation refer-ence decoder for applications frompostproduction to DVD authoring andDTV broadcast. The new LM100 loud-ness meter, which provides a broadcast-friendly solution for measuring the sub-jective loudness differences of content,will also be shown.

DORROUGH ELECTRONICS(Woodland Hills, CA, USA) manufac-tures audio loudness meters featuringthe trademark of Peak and Average fora highly accurate reading. These analogand digital reading meters are used intransmission, recording, postproduc-tion, mastering, sound reinforcement,and surround sound.


DTS (Agoura Hills, CA, USA) is aninnovator in the development of multi-channel digital sound solutions for theconsumer electronics and professionalaudio markets, including home A/V;video games and consoles; personalcomputers; and mobile and portable au-dio systems. Today, major consumerelectronics manufacturers support DTStechnology. Addressing the demand forDTS-encoded content worldwide, thecompany offers hardware and softwareencoders to the professional audio com-munity, allowing it to produce DTSaudio content directly.


EASTERN ACOUSTIC WORKS,INC. (Whitinsville, MA, USA) is aleader in the design and manufacture ofprofessional loudspeaker systems. Thefirm also oversees the development andoperation of SIA Software, manufactur-er of SMAART-Live acoustical mea-surement and analysis software. Forover two decades, Eastern AcousticWorks has helped to advance the pro-fessional audio industry with such tech-nology as the patented radial phaseplug technology, virtual line array, andphase point source technology.


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ELECTRONIC MUSICIAN MAGA-ZINE (Emeryville, CA, USA) will dis-play Electronic Musician, a publicationwritten specifically for musicians interested in recording in a home orpersonal studio. The magazine fea-tures new product announcements,qualitative product reviews by industryprofessionals, and coverage of all as-pects of music production from initialconcept to CD production and liveperformances.

ELECTRO-VOICE (Burnsville, MN,USA) is a brand of Telex Communica-tions, the manufacturer of high-qualityprofessional audio equipment includ-ing loudspeakers, mixing consoles, sig-nal processing, microphones (wiredand wireless), intercom, and duplicat-ing equipment (CD and cassette tape)under the Telex, Electro-Voice, Midas,Klark Teknik, and RTS brands.

EMTEC MULTIMEDIA, INC. (Valen-cia, CA, USA) originated modern taperecording in 1936, and has since thenremained a leader in magnetic mediaproducts. Studio products available areSM 900, SM 911, SM 468, LM 526,LPR 35, LTO, Chrome Extra and FerroExtra cassettes. Digital Master productsinclude DM 931, ADAT Master, DTRSMaster, DAT Master, and CD-R Master.The company also produces accessoriesand a wide range of DATA Media back-up products.

FRAUNHOFER INSTITUTE FORINTEGRATED CIRCUITS (Erlangen,Germany), a leader in high-quality lowbit-rate audio coding, will feature theMPEG layer-3 (MP3) and MPEG-4AAC. The firm contributes to manystandards bodies including 3GPP, AES,DVB, and ISMA.

GEFEN SYSTEMS, INC. (Wood-land Hills, CA, USA) will exhibitsamples of its products including 4 x 1DVI switcher, VGA to ADC conver-sion box, VGA to DVI conversionbox, DVI to ADC conversion box,DVI to ADC conversion box, DVIhub, CAT51000-5000 extenders, andthe USB 500, which extends USB to1650 feet, as well as SFXNet soundeffects locator and audition softwarefor digital workstations.

GEOFFREY DAKING & CO., INC.(Wilmington, DE, USA) will exhibitthe 1112 recording console, an all-dis-crete, class-A, transformer-coupled system. Features include: Jensen transformer-coupled microphone-preamplifier, 4-band equalizer, fivefrequencies on each band, high- andlow-pass filters, relay hard bypasspad, phantom-power switch, phasechange, stereo bus plus 8 output bus-es, 4 auxiliary sends, and pre- andpostproduction.

GEPCO INTERNATIONAL, INC.(Des Plaines, IL, USA) is a manufac-turer of audio and video cables, cableassemblies, and specialty cable prod-ucts. Audio cables include multi-pair/dual pair, single pair, multiconduc-tor, loudspeaker, guitar/instrument,microphone, and digital audio. All ca-bles can be cut to customer’s specifica-tions. GEPCO also distributes forADC, Neutrik, Switchcraft, EDAC,AMP, and other quality manufacturers.

GIBSON LABS (Redondo Beach,CA, USA) will exhibit their digital net-working products, amplifiers, sound re-inforcement loudspeakers, monitorloudspeakers, and their devices forsound systems.

GML: GEORGE MASSENBURGLABS, LLC (Franklin, TN, USA) willdisplay the new 2020 high-resolutiondiscrete input channel which includesthe well-known GML preamplifier,parametric equalizer, and dynamicrange controller. Also on exhibit will bethe complete GML line.

GOLD LINE/TEF (West Redding, CT,USA), an American manufacturer ofprofessional audio test equipment anddigital balanced and unbalanced equal-izers, will exhibit TEF analyzers withnew software and portable RTAs withnew intelligibility software formeasuring STI-CIS and RASTI. Thecompany manufactures a complete lineof SPL meters, phase testers, and multi-plexers for the studio.

GORDON INSTRUMENTS(Nashville, TN, USA) produces theGordon microphone preamplifier sys-tem, a two-channel, discrete, FET

preamplifier with separate gain controlwhich inserts the minimum gain need-ed using variable-gain, open-loop am-plifiers. Output load compensationsenses the load and adjusts the outputstage to achieve the lowest distortion.

GOTHAM AUDIO CABLE (Regens-dorf, Switzerland). See preview for Cable Factory, p. 617.

GREAT RIVER ELECTRONICS,INC. (Inver Grove Heights, MN, USA)designs and manufactures microphonepreamplifiers, equalizers, and custommixing equipment for location record-ing as well as broadcast. Other OEMproducts include audio/video confer-ence support equipment and militarytelecommunications hardware.

H.E.A.R. (Hearing Education andAwareness for Rockers) (San Fran-cisco, CA, USA) is a nonprofit volunteerorganization dedicated to raising aware-ness of the dangers of repeated exposureto excessive noise levels from music,which can lead to permanent hearing lossand tinnitus, through education aware-ness and grassroots outreach advocacy.


HHB COMMUNICATIONS USAINC. (Los Angeles, CA, USA) willfeature the new HHB Portadrive loca-tion sound recorder and the HHBCDR830 BurnIT PLUS fully featuredprofessional CD recorder. Completelyupdated HHB recording media on dis-play will include the DVD-R4.7GBgeneral, DVD-R4.7GB authoring,DVD-RW4.7GB, DVD-RAM4.7GB,and DVD-RAM9.4GB. The firm willalso demonstrate the HHB Portadisc,HHB circle monitors, new Rosendahlnanoclocks, new Lynx L22, and TL


EXHIBIT PREVIEWS

Audio Tube mixing consoles and sig-nal processors.

HOUSE EAR RESEARCH INSTI-TUTE (Los Angeles, CA, USA) willprovide hearing health and conservationinformation based on world-renownedhearing research and education, alongwith free hearing screenings, co-spon-sored by the AES, to all registered par-ticipants during convention hours. Fourpeople will be screened simultaneouslyin a mobile testing unit. A daily sign-upsheet will be available. Exclusivescreenings for exhibitors will take placefrom 9:00 am to 10:00 am.

IBIQUITY DIGITAL CORPORA-TION (Warren, NJ, USA) is the devel-oper of PAC™ compression technologyfor audio and data broadcast applica-tions. Backed by 15 of the largest radiobroadcasters, including ABC, ClearChannel and Viacom, and strategicpartners Ford Motor Company, Harris,Lucent, TI, and Visteon, iBiquity’scompression technology has been im-plemented in terrestrial IBOC andsatellite systems worldwide.

ILIO ENTERTAINMENTS (Malibu,CA, USA) will show the SpectrasonicsVirtual Instruments’ new line of sam-ple-based software plug-in instrumentsfor use with VST Macintosh/PC, MAS,and RTAS host programs. Three plug-ins have been released, including Sty-lus™, a vinyl groove module; Trilo-gy™, a total bass module; andAtmosphere™, a dream pad module.Each virtual instrument contains over 3GB of brand new sounds by producerEric Persing. ILIO Entertainments isthe exclusive North American distribu-tor of the Spectrasonics Virtual Instru-ments products.

IMAS PUBLISHING (Falls Church,VA, USA) is a leader in audio andvideo trade publications. These include:

Audio Media, Audio Media (Europeanedition), Pro Audio Review, RadioWorld, TV Technology, and Broadcastand Production.


INNOVA SON SA (Plougoumelen,France) has been active in sound rein-forcement digital console manufactur-ing since 1993 and has provided high-caliber clients, such as the BBC andRadio-France, with the acclaimedMuxipaire systems and Sensory con-soles. Based in Brittany, France, thecompany offers complete in-housemanufacturing and is represented inNorth America, Asia, and Europe.

INTERNATIONAL DJ EXPO (PortWashington, NY, USA), a leader ofpro-DJ shows, is proud to announce theexpansion of its show to include theClub Market Show, 2002 August26–29, in Atlantic City, New Jersey.The International DJ Expo/The ClubShow will be four days of seminars andthree days of exhibits catering to the DJand club markets.

IZ TECHNOLOGY CORPORA-TION (Burnaby, British Columbia,Canada), a leading manufacturer ofprofessional, multitrack hard disk audiorecorders will display RADAR 24®:Project and Project D, fully upgrade-able recording packages used in fixedand remote recording studios, scoringstages, and broadcast facilities through-out the world.


KLARK TEKNIK (Burnsville, MN,USA) is a brand of Telex Communica-tions, the manufacturer of high-qualityprofessional audio equipment includ-ing loudspeakers, mixing consoles, sig-nal processing, microphones (wiredand wireless), intercom, and duplicat-ing equipment (CD and cassette tape)under the Telex, Electro-Voice, Midas,Klark Teknik, and RTS brands.

KLIPPEL GMBH (Dresden, Germany)will feature its analyzer system, a versa-tile tool for assessing linear, nonlinear,and thermal parameters of loudspeakersover the full working range. It predictsthe large signal performance, simulatesdesign choices, and auralizes an audiooutput. The range of products has beenextended to include the Power Monitor,an eight-channel acquisition device forquality control, and software with fastdual-channel transfer function and dis-tortion measurement.

KRK SYSTEMS, LLC (Hollywood,FL, USA) will introduce new productsincluding the M218 main system moni-tor, the E12DSP and the redesignedE8T, part of the Expose line of moni-tors; and the improved KroK2 andRoKit2.

L-ACOUSTICS US (Oxnard, CA,USA), formerly Cox Audio Engineer-ing, manufactures and sells the L-ACOUSTICS loudspeaker systems, in-cluding V-DOSC, dV-DOSC, ARCS,115FM, and a complete line of loud-speakers that offer creative solutions todifficult audio environments. Using theproprietary concept Wavefront Sculp-ture Technology®, the arrayable loud-speaker systems offer the same acousti-cal structure as a single isophasic soundsource, thus eliminating comb filteringand greatly extending the near field.

LECTROSONICS, INC. (Rio Rancho,NM, USA) manufactures mixing prod-ucts and wireless microphone systemsfor conference centers, boardrooms, andtelevision stations worldwide. Productsfeatured will include: audio proces-


EXHIBIT PREVIEWS

sor, automatic mixers, 200 Series wire-less microphone system, and wirelessIFB equipment. The company will alsoprovide a special presentation of thenew digital wireless microphones.

LEXICON, INC. (Bedford, MA, USA)introduced one of the first digital pro-cessors in 1971 and has since become aworld leader in digital audio. The com-pany manufactures, among other things,multichannel digital reverberators andeffects systems; dual-channel proces-sors; and critically acclaimed home the-ater products.

LISTEN, INC. (Boston, MA, USA)will feature its SoundCheck™ softwarefor electroacoustics measurement, alow-cost, turnkey, PC-based QC testsystem for loudspeakers, microphones,headphones, head/handsets, hearingaids, and telecom systems up to 100kHz; the SCM series of low-cost mea-surement microphones; and the Sound-Connect™ low-noise, high-frequencymicrophone power supply for measure-ments up to 200 kHz.

LYNX STUDIO TECHNOLOGY,INC. (Newport Beach, CA, USA) de-signs and manufactures premium-quali-ty audio cards for Windows and Macin-tosh computers. The Lynx TWO andLynx L22 PCI cards offer 24-bit/192-kHz analog I/O with 117-dB dynamicrange and extensive synchronizationcapabilities. The LS-ADAT and LS-AES are 16-channel ADAT and 8-chan-nel AES I/O expansions modules.

MAGMA (San Diego, CA, USA) is atthe forefront of the PCI expansion in-dustry. The firm’s patented chassis arecompatible with any PCI-based com-

puter—PC and Macintosh plat-forms—desktop, tower, and laptops.Available in 2- to 13-slot configura-tions, four enclosures are offered:portable, desktop, tower, and rackmount. They have been approved byDigidesign to work with Pro Tools andare compatible with other companies’products.

MANLEY LABS (Chino, CA, USA)will exhibit the Manley SLAM. Comeby the booth to see this new stereo lim-iter and microphone preamplifier andto hear what all the loud noise is about.The full Manley crew will also demon-strate all other Manley and Langevinboxes.

MARQUETTE AUDIO LABS (Hay-ward, CA, USA) specializes in customracks for vintage modules, such as Tele-funken/Siemens, Neve, Calrec, Audix,and Langevin; and offers new, used, andvintage recording equipment, such asmicrophone preamplifiers, microphones,equalizers, compressor/limiters, andconsoles. Among the manufacturers rep-resented are API, Mercury RecordingEquipment Company, Soundelux Micro-phones, Brauner Microphones, Antares,ADL (Anthony Demaria Labs), PurpleAudio, Tri-Tech Konsoles, EmpiricalLabs (Distressor), Otari USA, Drawmer,Royer Labs Microphones, and EclairEngineering (Evil Twin).

MBHO MICROPHONES (Brooklyn,NY, USA) offers a variety of quality, af-fordable microphones for studio, mea-surement, and installation applications.The microphones have been used in stu-dio and installation applications, such asat the Kennedy Center in Washington,DC. MBHO microphones are complete-ly manufactured by hand in West Ger-many. Since 1999 the firm’s micro-phones have been distributed in the U.S.by MTC, New York City.

MERCURY RECORDING EQUIP-MENT CO. (Hayward, CA, USA)specializes in recreating classic Amer-ican and European tube equipmentfrom the 1950s and 1960s. Featuredwill be the Mercury 66 Limited Edi-tion, which is a variable bias-style, all-tube, all-transformer compressor. It issimilar to the Fairchild 660. Also

showcased will be the Mercury EQ-Hand Mercury EQ-P all-tube, all-trans-former equalizers, which are tributesto the earlier professional tube equal-izers, such as Pultec.

MEYER SOUND (Berkeley, CA,USA) is a leading professional loud-speaker manufacturer, with productsthat embody uncompromising engi-neering, dependability, and high-quali-ty sound. Based in Berkeley, Califor-nia, the company has branch offices inRussia, Spain, Germany, Australia,Benelux, and Mexico. Its products areused in some of the most prestigiousconcert halls, sports arenas, recordingstudios, Broadway shows, houses ofworship, and concert tours worldwide.From the Three Tenors and CarnegieHall to the Montreux Jazz Festival andleading rock acts, Meyer Sound haspowered some of the world’s brighteststars, providing them with the means toreach their audiences with clarity andpower.

MICROBOARDS TECHNOLOGY,LLC (Chanhassen, MN, USA) is amanufacturer of CD and DVD record-able products. Traditionally known forits award-winning duplicators, the firmalso offers equipment for recording,printing, etc. Microboards has been anindustry leader in CD and DVD sinceits inception and has offered a com-plete line for over 10 years.

MIDAS (Burnsville, MN, USA) is abrand of Telex Communications, themanufacturer of high-quality profes-sional audio equipment including loud-speakers, mixing consoles, signal pro-cessing, microphones (wired andwireless), intercom, and duplicatingequipment (CD and cassette tape) underthe Telex, Electro-Voice, Midas, KlarkTeknik, and RTS brands.

MILLENNIA MUSIC & MEDIASYSTEMS (Placerville, CA, USA)will unveil the HV-3C/24 microphonepreamplifier with 24-bit, 192-kHzPOW-r A/D converter. Also on exhibitwill be the well-known STT-1 OriginTwin Topology recording system andthe LPE-2 Legacy archiving system.Come by the booth to see why the HV-3 microphone preamplifiers have be-


EXHIBIT PREVIEWS

come a standard in classical and criticalacoustic music recording. In addition,the company will show a complete lineof vacuum tube and solid-state micro-phone preamplifiers, equalizers, com-pressors, mixers, M-S decoders, discreteamplifier modules, among others.

MIX MAGAZINE (Emeryville, CA,USA) will display Mix, the leadingmagazine for the professional record-ing and sound production industry.Mix covers the entire spectrum of pro-fessional audio and music, such as stu-dio recording, live sound production,sound for picture and multimedia, digi-tal audio technology, facility designand construction, tape/CD replication,broadcast production, and education.Stop by the booth to pick up a freecopy of Mix.

MSOFT INC. (Woodland Hills, CA,USA) provides audio and video turnkeyserver systems with all and any SFX ormusic library audio predigitized for theproduction industry. These systems canconvert file formats and are cross-plat-

form and cross-DAW. ServerSoundmanages SFX, and the new MusicCueserver has a three-level “drill down”production music search.

THE MUSEUM OF SOUNDRECORDING (New York, NY, USA)provides a forum to reveal the impactrecording makes on history, society,and culture. It also offers the opportuni-ty to stand back and see how celebrat-ing our industry advances the art ofsound. MOSR’s new home is the RKOKeith’s, a grand vaudeville theater, inQueens, New York.

THE MUSIC AND SOUND RE-TAILER (Port Washington, NY, USA)

will display The Retailer, a magazinefor musical instrument and profession-al audio dealers. The magazine is botheditorially and visually vibrant, fresh,energetic, and lively. MI retail person-nel owners, managers, and salespeopleneed a magazine whose number onepriority is reporting on the dramaticchanges occurring in music retailing.The Retailer has over 11 000 sub-scribers in the U.S.

MYTEK DIGITAL (New York, NY,USA) will exhibit the D-Master-DSDmaster recorder, the Stereo 96 minia-ture audiophole stereo A/D and D/Aconverters, and the 8 x 96 Series ofdigital converters with interfaces fornuendo, sonic, and other popularDAWs. The DDD603 96-kHz digitalmeter will also be on display alongwith the PrivateQ multichannel head-phone system.

THE NATIONAL ACADEMY OFRECORDING ARTS AND SCI-ENCES, INC. (RECORDINGACADEMY) (Santa Monica, CA,


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USA) is a nonprofit organization ofmore than 20 000 musicians, produc-ers, and other recording professionals.Best known for the GRAMMY®

Awards, the Recording Academy isalso responsible for numerous ground-breaking outreach programs involvingeducation, human services, and cultur-al enrichment. Membership is open tomusic professionals and others whosecareer activities relate to the record-ing/music video industry.

NATIVE INSTRUMENTS USA(Los Angeles, CA, USA) is a leadingmanufacturer of software synthesizersfor personal computers and a strongbrand in the field of music and audiosoftware. Founded in 1996, the firmwas one of the first companies to usethe possibilities of real-time soundsynthesis on Macintosh and Windowsplatforms. Products are targeted at both audio professionals and hob-byists and have won practically allrelevant awards by the music technol-ogy press. The company is known for its quality products and innova-tions within the computer and audioindustry.

AES SUSTAINING MEMBER

NEUMANN/USA (Old Lyme, CT,USA) manufactures and distributeshigh-quality recording microphones.Founded in 1928 by Georg Neumannin Berlin, Germany, the microphoneshave long been recognized as stan-dards by the recording/music indus-try. Since 1991, Sennheiser/USA hasbeen the distributor of Neumannproducts.


NEUTRIK USA, INC. (Lakewood,NJ, USA) manufactures solder andIDC terminated analog and digitalXLR connectors, 1⁄4- in jacks andplugs; EasyPatch TT and TB pro-grammable patchbays; patchcords;PatchLink SPL® 1⁄4-in balanced patchpanels; circular DIN and RCA con-nectors; 3.5-mm plugs; BNC connec-tors; and a full accessory line includ-ing DMX adapters. Brand namesinclude Ethercon®, Speakon®, Power-con®, and Minstruments. The firmalso has the line of REAN productsincluding plastic knobs; sliders; but-

tons; TT, TB, and RPM patchbaysand quad cords; and 1⁄4-in jacks.

NHT PRO (Benicia, CA, USA) willdisplay the ABC 5.1 system, consist-ing of two pairs of A-20 monitors, B-20 stereo/mono subwoofer, and C-20center channel monitor, each with itsown high-powered control amplifier;the M-00 versatile, powerful, compactpowered mini-monitor; the S-00 pow-ered subwoofer designed for use withthe M-00; and the PVC high qualitystereo passive volume control.

OPTICOM GMBH (Erlangen, Ger-many) will feature OPERA™ – YourDigital Ear, the comprehensive newfamily of voice and wide-band audioquality testers developed to objective-ly analyze the perceived audio qualityof compressed signals. OPERA™combines the latest ITU standards,such as PESQ (P.862), PSQM+(P.861), and PEAQ (BS.1387), tobenchmark the audio quality, as per-ceived by customers. The OPERA™suite ranges from software-based so-lutions to fixed and portable stand-alone testers, which are suitable totest and improve the speech quality ofapplications, such as VoIP, as well asthe wide-band audio quality of AAC,MP3, among others.

OTARI CORPORATION (CanogaPark, CA, USA) has been a leadingmanufacturer of professional audioproducts for the broadcast, postpro-duction, music recording, and livesound markets for over thirty-fiveyears. The firm’s current product lineincludes: analog and digital recorders,mixing consoles, digital audio formatconverters, and high-speed audio,video, and CD duplication systems.

PELONIS SOUND & ACOUS-TICS, INC. (Santa Barbara, CA,USA) provides acoustical studio de-sign and consultation.

PENNY & GILES CONTROLSINC. (Schaumburg, IL, USA) will dis-play a full range of manual and motor-ized faders, joysticks for camera con-trol, analog and digital t-bars, andprofessional cross-fader. Also featuredwill be company’s line of Mosses and

Mitchell audio and video jackfieldsand audio flexipatch.

PILCHNER SCHOUSTAL INTER-NATIONAL INC. (Toronto, Ontario,Canada) specializes in the design andconstruction of recording and broad-cast facilities. Having created over 500facilities, the firm offers compellingand innovative approaches to acousticarchitecture.

PMC MONITOR COMPANY (Lu-ton, Beds., UK) is recognized as abuilder of world-class audio monitors.The firm utilizes a transmission-lineconstruction in all of its active andpassive systems. PMC monitors deliv-er low-frequency extension, higherSPLs without distortion or compres-sion, and a neutral yet dynamic band-width. The firm’s products are exclu-sively distributed in North America byBryston Ltd.

PMI AUDIO GROUP (Torrance, CA,USA) will display the Studio Projectsmicrophones, the Sony professionalaudio products, the Groove Doctorsaudio loops, the Toft Audio Designsignal processors, and the Joemeeksignal processors.

POST MAGAZINE, ADVANSTARCOMMUNICATIONS INC. (NewYork, NY, USA) will feature POST, amonthly and BPA-audited magazinethat reaches over 30 500 subscribersworking in all forms of entertainmentmedia. POST serves and showcasesthe works of a unique community ofcreative, production, and technicalmanagers whose artistry, editing, andtechnical talents build higher qualityproductions.


PRIMEDIA (Overland Park, KS,USA) will feature its EntertainmentDivision’s publications and events,such as Mix, Internet Audio, MixMaster Directory, Sound and VideoContractor, Residential Contractor’sProduct Source Guide, ElectronicMusician, Onstage, Remix, Enter-tainment Design, World BroadcastEngineering, Video Systems, BE Ra-dio, Millimeter, Lighting Dimensions,and LDI.


EXHIBIT PREVIEWS

PRISM MEDIA PRODUCTS (Rock-away, NJ, USA) will exhibit the ADA-8 multichannel AD/DA converter,which is compatible with modernworkstations and dScope III, the ulti-mate in analog and digital audio testand measurement systems. The rangealso includes stereo AD/DA convert-ers, equalizers, compressors, and mi-crophone preamplifiers. The firm hasbeen at the forefront of technology forover a decade.

PROFESSIONAL AUDIO DE-SIGN, INC. (Rockland, MA, USA)offers everything for the audio pro-fessional, such as turnkey studio de-sign equipment packages, large-for-mat consoles, tape machines, custommonitoring systems, microphones,and new, used, and vintage gear. Thecompany is an SSL authorized re-seller of refurbished and warrantedconsoles and the U.S. representativefor Munro Associates acoustic designand Dynaudio/Munro custom moni-toring systems.

PWM SYSTEMS (London, UK) hasbeen involved with high-fidelity re-search since 1973. The firm is one ofthe first design houses to solely spe-cialize in this area of electronics. As aresult of this ongoing research, manyprestigious companies worldwide areeither using or currently developingaudio systems based on technologysupplied by PWM Systems. Companypersonnel will be at the booth to dis-cuss the newest developments. Topicswill range from 300-W to 3-kW am-plifiers, powered loudspeakers, andhigh-fidelity DVD and SACD outputstages.

QUESTED MONITORING SYS-TEMS (Wannakee, WI, USA) offers afull range of high-quality referencemonitors and power amplifiers. Newproducts featured will include the F5monitor and F19 subwoofer system, acompact monitor worthy of a refer-ence designation. Also shown will bea full range of studio-grade power am-plifiers and analog crossovers.

RADIAN AUDIO ENGINEERING,INC. (Orange, CA, USA) will exhibitits newest products including the 365

6.5-in coaxial transducer, 950PBneodymium compression driver, andRMW-1122 12-in and RMW-1152 15-in MicroWedges. The 365 is designedfor low-cost, high performance ceilingapplications. The 950PB features ad-vanced neodymium driver technologyand has an extremely low distortion.The MicroWedge is a compact, ar-rayable floor wedge with a uniqueshape and very low profile.


RANE CORPORATION (Mukilteo,WA, USA) will introduce the newestaddition to its family of Drag Net®

software-controlled digital signal pro-cessors, the RPM26z. It is a fully user-configurable 2-in, 6-out device. Thelatest version of Drag Net® softwarewill also be shown. In addition, thefirm will feature the AC 24 stereofour-way crossover (digital with ana-log control) and the Empath mixer forremixers and performing DJs.

RCS (White Plains, NY, USA) pro-vides music database managementsoftware and scalable digital audiostorage and playback technology. Mul-tiple channels of programming can beplayed from a workstation inAES/EBU or analog audio or can bedynamically encoded and streamed inWindows® Media File format. Thecompany also provides Internet audiocontent creation and delivery, includ-ing the provision for users to cus-tomize music based on preference.Graphics can be synchronized to mu-sic for a richer user experience.

RENKUS-HEINZ, INC. (FoothillRanch, CA, USA) will feature its newPN/PNX and ST/STX loudspeakerlines, all optionally available withbuilt-in amplification; the Renkus-Heinz LonWorks-based R-Control Re-mote Control and Supervision Net-work; and the CobraNet AudioDistribution Network interface facili-ties EASE 4.0. The Enhanced Acous-tic Simulation software program willalso be on display.

RESOLUTION (London, UK) willfeature Resolution, the next-genera-tion audio production magazine fortoday’s audio professional. With a

rich mixture of news, reviews, appli-cation features, interviews, facility re-ports and commentaries, Resolutionoffers professional audio end users adefinitive take on the technology,techniques, and trends that drive thefast-changing professional audio pro-duction marketplace of the twenty-first century.

RODE MICROPHONES (Torrance,CA, USA) will exhibit the NT5 smalldiaphragm pen microphone, customtailored for instruments packaged asmatched pairs; the NT4 small di-aphragm stereo microphone; the NTKtube microphone; the NT 1000 micro-phone; the NT3 microphone; the NT2microphone; the NT1 microphone; thebroadcaster microphone; and the Clas-sic II microphone. All microphonesemploy true condenser custom-madecapsules.

ROHDE & SCHWARZ GMBH &CO. KG (Munich, Germany) will pre-sent a range of audio analyzers fortesting audio components in both theanalog and digital domains. The unitscan handle all necessary measure-ments including 96 kHz, 24 bit. Alsoshown will be the latest products,such as the audio switcher UPZ andmeasurements on Dolby Digital decoders.

RTS (Burnsville, MN, USA) is abrand of Telex Communications, themanufacturer of high-quality profes-sional audio equipment includingloudspeakers, mixing consoles, signalprocessing, microphones (wired andwireless), intercom, and duplicatingequipment (CD and cassette tape) un-der the Telex, Electro-Voice, Midas,Klark Teknik, and RTS brands.

SABINE, INC. (Alachua, FL, USA)manufactures professional audioequipment, including the new TrueMobility™ 2.4-GHz Spread Spectrumwireless microphones; True Mobility™

UHF and VHF wireless microphones;Graphi-Q, an award-winning 31-banddigital equalizer with analog interface,FBX®, compressor/limiter, and delay;and Power-Q, a combination of ninedigital professional audio products inone 2-U box.

EXHIBIT PREVIEWS


SCHOEPS/REDDING AUDIO, INC.(Newtown, CT, USA) will exhibit theSchoeps microphones, which are hand-crafted in Germany. The microphonesare well known for their natural soundand precision craftsmanship. The Co-lette Series offers over 20 differentcapsules and various accessories forstudio recording, broadcast, and filmsound. Also on exhibit will be the ul-tracompact CCM Series, the PolarFlexsystem, and the KFM360 5.1 surroundmicrophone.

SE ELECTRONICS (Rohnert Park,CA, USA) will introduce the new ZSeries professional microphones,which feature large 1.07-in gold-sput-tered diaphragms, tube microphones,class-A FET microphones, low noise,and multiple patterns (up to nine posi-tions). Also shown will be the new SECustom Series microphones with im-proved performance and appearance.


SENNHEISER ELECTRONICCORP. (Old Lyme, CT, USA) is aleader in microphone technology, RFwireless and infrared sound transmis-sion, headphone transducer technolo-gy, and recently in the development ofactive noise cancellation. Sennheiserwas established in Wedemark, Ger-many, in 1945. Sennheiser/USA alsorepresents and distributes Neumann,D.A.S., True Systems, Chevin, and In-nova-Son products. Sennheiser/USA isa wholly owned subsidiary.

SHEP & ASSOCIATES (Wannakee,WI, USA) manufactures a range of dis-crete, transformer-coupled microphonepreamplifiers and equalizers, which are

fully compatible with the Neve 80 se-ries consoles or outboard rack frames.Also featured will be the SNDC6 stereocompressor/limiter with a fully discreteand transformer-coupled design.

SOUND & COMMUNICATIONS(Port Washington, NY, USA) will fea-ture Sound & Communications, a mag-azine for professionals who design,specify, and install audio and AV sys-tems in commercial and professionalvenues. Sound & Communications istailored to be the source for applica-tions, news, business, and technologyfor the commercial installation and in-tegration marketplace. The magazine,which was established in 1955, nowreaches over 20 000 readers monthly,making it one of the more widely circu-lated contracting journals in America.

SOUND & VIDEO CONTRACTORMAGAZINE (Emeryville, CA, USA)will feature Sound & Video Contractor,a leading systems contracting maga-zine that provides solutions to real-lifeinstallation challenges. Each issue ofS&VC is filled with in-depth, how-toarticles; installation profiles; and in-dustry advice on every aspect of sys-tems integration including sound,video, security, communications, datatransmission, home theater, and resi-dential electronic systems. Stop by thebooth to pick up a free copy of S&VC.


SOUND ON SOUND (Bar Hill,Cambridge, UK) will feature SoundOn Sound magazine. With its new in-ternational edition reaching even moreterritories around the world, Sound OnSound is recognized as the recordingtechnology bible for professionals andproject studios. Every issue is packedwith authoritative reviews of all thehottest new products from synths andsamplers, mixers, microphones, andmonitors to computer recording sys-tems. Its tutorial articles offer no-non-sense practical advice and insight forexperts and beginners alike.

SOUNDELUX MICROPHONES(Hollywood, CA, USA) will show theELUX 251 tube microphone, E 47 tubemicrophone, U99 tube microphone,and U195 FET microphone.

SPARS (Memphis, TN, USA) is anonprofit organization that serves as abusiness connection for audio profes-sionals, helping its members sharepractical, hands-on business informa-tion about facility ownership, man-agement, and operations. Faced withincreased competition, emergingtechnologies, financial pressures anda need for solid business information,today’s audio professional needs seri-ous resources when making deci-sions, evaluating technology, findingsdirection, and staying creative. TheSociety of Professional AudioRecording Services was establishedover 22 years ago.

SRS LABS, INC. (Santa Ana, CA,USA) is a leading provider of ad-vanced audio and voice technology so-lutions for broadcast, streaming media,and consumer markets. Demonstra-tions will include: the Circle SurroundProcessor, multichannel encoding/de-coding technology that enables up to6.1 channels of audio over any 2-chan-nel carrier; and the BSP for improve-ment of dialog in broadcasting.

STEINBERG NORTH AMERICA(Chatsworth, CA, USA) will exhibit theNuendo Media Production Software forthe Nuendo media production system, ahost-based modular digital audio work-station. The software is based on a 32-bit floating-point audio engine with upto 384-kHz resolution and featurespowerful editing, surround sound, pro-cessing, and mixing. Also shown willbe the Nuendo Surround Edition, a setof six, fully automatable plug-ins de-signed exclusively for the Nuendo sys-tem. The Surround Edition offers up toeight channels of compression, equal-ization, loudness maximization, rever-beration, and LFE management. Sur-round Edition is designed to meetmultichannel mixing needs. The Nuen-do system hardware line includes:96/52 PCI digital audio card with 3Toslink, S/PDIF, ADAT sync, and wordclock; eight I/O 96k audio interfacewith 8 I/O analog, ADAT and TDIF,each at 96 kHz; TimeLockPro withword clock, LTC, VITC, and Digi-Su-per clock fast-locking sync box; DD8digital format and rate converter withAES/EBU, ADAT, and TDIFF; Au-


EXHIBIT PREVIEWS

dioLink 96 Mobile PMCIA Type II au-dio card with full 24-bit/96-kHz sup-port; AudioLink 96 PCI 24-bit/96-kHzPCI card based on the Nuendo 96/52;AudioLink 96 Digiset with 3x ADATI/O, S/PDIF IO, ADAT sync in, wordclock I/O (BNC), analog line/head-phone output, and 2x MIDI I/O with 32channels of MIDI; and AudioLink 96Multiset with 8x analog line I/O (24bit/96 kHz, 106 DBA, 1⁄4-in TRS jacks),ADAT, S/PDIF, work clock, headphonejack, and MIDI I/O.


STUDER NORTH AMERICA INC.(Toronto, Ontario, Canada) is an inter-national company offering turnkey sys-tem solutions for the broadcast, postpro-duction, and film industries. The firm’swide range of professional products in-cludes: digital mixing systems, digitalaudio routing systems, digital radio/con-tinuity consoles, analog and digitalrecorders, and active studio monitors.

STUDIO NETWORK SOLUTIONS(St. Louis, MO, USA) will feature itsfiber-channel hard drive systems,which allow the user to increase thestability and performance of digital au-dio and video workstations with amaz-ing speed and reliability from onedrive. The firm has become a leader inaudio/video storage area networking.

SUMMIT AUDIO INC. (Watsonville,CA, USA) will show three full lines ofmicrophone preamplifiers, compressorsand equalizers, including the new 2BA-221 microphone and line module withdigitally controlled Element 78 line ofclass-A solid-state processors, the A-linevacuum tube processors, and the newone-half rack line of audio processors.

SUNRISE E. & E., INC. (DiamondBar, CA, USA) is one of the largestspecialized manufacturers of toriodal,EI, and R core electromagnetic powertransformers in China. They offerOEM and ODM service and custom-made products with competitive pric-ing, timely delivery, and strong cus-tomer service. The company is ISO9002, UL, TUV, and CE certified.

SWITCHCRAFT INC. (Chicago, IL,USA) is a leading manufacturer of in-

terconnectable audio products. Thefirm’s broad product line includes audioconnectors, audio adapters, audio patch-bays and patchcords, and jacks/plugs.Products include XLR, HPC Series,MIDI, 3.5-mm, 1⁄4-in, RCA, BNC, andboth bantam and long-frame patchproducts. See the new EX Norm patch-bay at the company’s booth.

SYNTRILLIUM SOFTWARE COR-PORATION (Phoenix, AZ, USA) willdisplay the Cool Edit Pro digital audiorecorder, editor, and mixer for Windows.With support for 128 stereo tracts, inte-grated wave editor, over 45 DSP effects,32-bit/192-kHz recording, real-time ef-fects, restoration tools, batch processing,looping tools, and MTC master, it is acomplete audio editing solution.

SYSID LABS (Berkeley, CA, USA) willexhibit acoustical measurement equip-ment and audio measurement equipment.


TASCAM (Montebello, CA, USA) of-fers cassette duplicating equipment,

CD/DVD production equipment, com-pact disc equipment, digital recordingequipment, digital workstations, pro-duction music and sound effects prod-ucts, recording mixing consoles, andsurround sound products.

TECA (Guidate Camuno (BS), Italy)designs and produces toroidal audiopower transformers and audio distribu-tion transformers.

TELEX COMMUNICATIONS(Burnsville, MN, USA) is a manufac-turer of high-quality professional audioequipment including loudspeakers,mixing consoles, signal processing,microphones (wired and wireless), in-tercom, and duplicating equipment(CD and cassette tape) under the Telex,Electro-Voice, Midas, Klark Teknik,and RTS brands.

TESTA COMMUNICATIONS (PortWashington, NY, USA) is a leadingpublisher and producer of informationfor the professional electronic enter-tainment and information industries.


EXHIBIT PREVIEWS

BBBBSSSSWWWWAAAA TTTTEEEECCCCHHHH

BSWA Technology Co., LtdPhone: 86-10-625-25350; Fax: 86-10-6200 [email protected] www.bswa.com.cn

With 30-year experiences in making measurement microphones, BSWA winsreputation in OEM markets. The leading acoustic instrument companieschose BSWA microphones for their Audio and Measurement Products. Wecan design a microphone (from 1/4” to 4 in” ) meeting your special needs.

BSWA MICROPHONES

Publications and shows include: Sound& Communications, Club Systems In-ternational, The Music & Sound Re-tailer, DJ Times, The Blue Book, Inter-national DJ Expo/The Club Show andDJ Expo West/The Club Show. Con-vention TV @ AES, a part of Testa’sConvention TV division, is produced atAES Conventions each day of theshow. VTTV Studios is a full-serviceproduction and postproduction facility.


UNITED ENTERTAINMENT ME-DIA, A CMP COMPANY (New York,NY, USA) produces magazines, books,Web sites, and trade shows for musi-cians and the professional audio,video, and installation industries in-cluding EQ, Pro Sound News, Sur-round Professional, Medialine, Sys-tems Contractor News, ResidentialSystems, Rental & Staging Systems,Videography, Government Video, Digi-tal TV, Digital Cinema, DVD Enter-tainment (coproduced with IRMA)Government Video Technology Expo,Surround Conference, Guitar Player,Bass Player, Keyboard, GIG, MCRumble, The Music Yellow Pages, andBackbeat Books.

UNIVERSAL AUDIO (Santa Cruz,CA, USA) is a manufacturer of high-quality solid-state and tube micro-phone preamplifiers, limiters, andcompressors.

VIDIPAX (New York, NY, USA) is astate-of-the-art magnetic mediarestoration company. The firm has de-veloped proprietary techniques to cleanand remaster audio and video tapesthat have been recorded on obsoleteformats damaged by smoke, water ordeterioration as a result of neglect orold age.

VIENNA SYMPHONIC LIBRARYGMBH (Vienna, Austria) will exhibitthe Vienna Symphonic Library.

WAVE ARTS, INC. (Arlington, MA,USA), developer of professional audioplug-ins and DSP technology, willdemonstrate the new version 3.0 plug-ins for VST (Macintosh/PC) and Di-rectX hosts. Featured will be theTrackPlug, an all-in-one EQ, compres-

sor, and gate plug-in.

WAVE DISTRIBUTION (Ringwood,NJ, USA) will feature products fromChandler Limited, CLM Dynamics,Empirical Labs, Reel Drums, andTruth Audio.

WAVE SPACE, INC. (FoothillRanch, CA, USA), a full-serviceacoustical design and engineering firmspecializing in recording, video, mo-tion picture and broadcast facilities,will display photographs and drawingsof recent projects, including The Ad-ventist Media Center, CatamountRecording, Glenwood Place Studios,One Union Recording, Pacifique Stu-dios, and The Post House.

WAVES LTD. (Knoxville, TN, USA),a leading supplier of DSP software, isnow a leading supplier of signal pro-cessing and user interfaces for theWindows and Macintosh professionalaudio and multimedia markets. Thecompany’s mission is to continue toprovide products of high sonic qualityand to enhance the production capabil-ities of digital audio recording.

WEST PENN WIRE/CDT (Wash-ington, PA, USA) is a leading manu-facturer of electronic wire and cablefor the broadcast industry. Cables in-clude digital video, digital audio,RGB/sync, analog snake audio, andPro-Video.

WESTLAKE AUDIO (Newbury Park,CA, USA) is celebrating over 30 yearsin the professional audio business. Thecompany continues to offer accuratestudio monitoring systems for record-ing and broadcast professionals. Its ex-tensive product selection ranges fromnear-field to large main monitors.

WHISPERROOM, INC. (Morris-town, NJ, USA) manufactures portable

sound isolation rooms, such as vocalbooths and broadcast rooms. Nineteensizes and two levels of isolation areavailable. Standard features includedoor window, ventilation system(s),cable passages, and acoustical foam.Optional features include wall win-dows, caster plates, ventilation silenc-ing system(s), and SoundWave deflec-tion system.

WIREWORKS CORPORATION(Hillside, NJ, USA) is a leading manu-facturer of audio and video cablingsystems. Products include: an exten-sive line of multipin-based discon-nectable cabling components; trans-former-isolated microphone splitters;audio/video multipin cabling systems;microphone, coaxial, loudspeaker, andcontrol cable assemblies; WireLUX, anew line of premium-quality audio ca-bles; Perfect Custom panels; and TE-3+, TEN-4, and TEC256 cabletesters.

WOHLER TECHNOLOGIES (SouthSan Francisco, CA, USA) producesself-powered, in-rack audio monitoringsystems. The company provides indus-try monitoring options, which includeanalog, AES/EBU, SDI, Dolby AC-3and Dolby E, and features high-resolu-tion level meters containing tri-colorLED. Also available from the Wohlerproduct line are Panoramadtv LCDvideo monitors with dual, triple, andquad screens.

WORLD LINK DIGITAL (Burbank,CA, USA) maintains one of the largestinventories of portable Pro Tools edit-ing systems for postproduction andrecording applications. Along with ProTools, the firm offers Nuendo systems,MOTU, digital dubbers, TC6000, Nevemodules, tube microphones, profes-sional control and portable surroundsystems. The company also providesinstallation and technical support forprivately owned systems.

YAMAHA CORP. - MLAN LI-CENSING OFFICE (Buena Park,CA, USA) will show the latest tech-nology for the digital audio networkwith products from licensees. The firmwill discuss in detail the mLAN Li-censing Program.


EXHIBIT PREVIEWS

OF THE

SECTIONSWe appreciate the assistance of thesection secretaries in providing theinformation for the following reports.

NEWS


Music EffectsFifteen Japan Section members gath-ered at the Seijyo Club in Tokyo onMarch 20, to hear Masashi Yamada ofthe Osaka University of Arts talk aboutthe effect of background music onscore performance in an auto-racinggame. Using the game as a simulationtool, Yamada was able to investigatehow music influences car maneuver-ability, i.e., the user’s ability as repre-sented in the form of lap times.

Yamada, who was inspired by a recent study on the interaction betweenauditory and visual processing in caraudio, devised several experimentswhereby subject’s lap times were mea-sured using ten different types of music, including no sound at all. Aspart of the study, the gamers werequestioned on their impressions of boththe music and the game as separateentities.

Yamada then analyzed results usingthe Semantic Differential Method tochart the relationships between themusic, the game, and user’s scores. Hefound that the best lap time was obtained with no music, and congru-ently, some of the musical selectionsactually degraded the score signifi-cantly. For instance, darker or moreagitating music confused the game bydisturbing drivers’ concentration in

the race. At the end of the study, Yamada concluded that music doesnot always have a good effect on behavior. In light of his findings, hesuggested that more careful considera-tion should be taken when applyingmusic to environmental designs.

T. Kamekawa and Vic Goh

Jazz Recording and MixingJim Anderson, recording engineer,spoke to more than 40 engineers of theAlberta Section at the Banff Centre’sTelus Studio in Alberta, Canada,about jazz recording and mixing onMay 19. Anderson has worked behindthe board for some of the top artists injazz, including Terence Blanchard,Ron Carter, Joe Henderson, JJ John-son, Branford Marsalis, McCoy Tyn-er, Phil Woods, John Zorn and others.At present, he is AES vice president,Eastern Region, and has also beenchair of the New York Section.

During the evening, Anderson playedsome of his work and told stories of hismyriad studio experiences in order tobest describe his studio techniques. Hespoke in detail about a Joe Hendersonsession, during which he successfullyrecorded the drums by placing multiplepairs of stereo microphones overheadand a stereo pair on the kick drum.

During a discussion of a Cyrus Chest-

nut session, he spoke about how, byplacing particular emphasis on microphone choice and position, imag-ing, and spaciousness, he was able toget the most out of the piano, wood-winds, brass, and strings. In terms of reverberation, Anderson admitted thathe prefers live chambers to reverb units.As such, he will go out of his way tocreate properly resonant conditions instairwells and other atypical venues.

Boston at WERSThe May meeting of the Boston Sec-tion was hosted by Emerson Collegeradio station WERS and featuredBerklee professor and renownedrecording and mix engineer, CarlBeatty. He spoke about the finer details of recording drums. Far morethan simply showing how to get thejob done, Beatty shared some of hismost effective, albeit unusual, record-ing secrets and techniques.

Beatty started with his conceptualapproach to making recordings by reminding the group that the drum kitis really one instrument, and if it is notrecorded this way it will require a lotof work to glue all the pieces together.Start by thinking about the room, saidBeatty, and about where the drumssound best. Look for symmetry later-ally and nonreflective surfaces, partic-ularly behind the drummer. Often, thebrightest and most cohesive soundsare found at the drummer’s perspec-tive or even behind the drummer.

To illustrate, Beatty invited membersof the audience to take turns listening to the kit from various vantagepoints in the room and around the kit.Gobos (moveable acoustic isolatingpanels used to enclose an instrument)were needed to absorb some of the re-flections from a glass window behindthe drummer, but with those in placewonderful tones were evident right

At Japan’s Marchmeeting M. Yamada(wearing glasses)spoke about the effectof background music on score performancein auto-racing.

ered at the NUS Guild House for aseminar on “Essential Basics in StudioAudio.” There were three sections forthe seminar: “Getting the Best Perfor-mance from Your Voice-Over (VO)Talent” by Joe Augustin, “What isPre-Mastering” by Aaron Pereira, and“How Do We Make Digital AudioWork?” by P. V. Anthony. Augustin iscurrently manager of SAFRA Radioand does voiceovers for radio, TVC,corporate videos, and other media.Pereira does premastering in Sono-Press, and has premastered titles forlabels such as VMP, Sony, BMG, andRock Records. Anthony, who also issection secretary, works in the digitalaudio studio Mind & Media. He spe-cializes in sound for picture, audiorestoration, and live recording.

After a brief introduction by RobertSoo, section chair, Augustin began theprogram by describing a typical voice-over recording session. He shared sev-eral important points that he saidwould help the performer deliver thebest results. He recommended that therecording engineer get more involved in the process and invest insome research before the session, suchas reading the script, pinpointing theessence of the story, understanding thecharacters, and generally goingbeyond the technical aspects to gain agreater understanding of the goals ofthe recording session.

A bit of preproduction work wouldalso provide the necessary sound effects and musical cues. All these ele-ments can help to establish a moodthat would be conducive to helping thevoice talent deliver a more convincingperformance.

Augustin then spoke about howscripts should be prepared down to thedetail, even in terms of font size, spac-ing and stapling. Although thesepoints may seem trivial, he said that inhis experience, a well-prepared scriptoften helps the actor concentrate andthus perform better.

He then talked about sound booth ergonomics, touching on air condition-ing, lighting, an adequate script holderand headphones. He added that it is im-portant to keep an open channel between the performer in the soundbooth, the audio engineer, and the other

ing or lowering the height of thestands to get more or less bass rein-forcement. These microphones, com-bined with the oddly placed omnis,provided the fullest representation ofthe kit, even without the kickmicrophone.

Beatty also demonstrated a few ofthe more traditional techniques using apair of Earthworks SR71 cardioidsplaced as overheads, an Audix D1placed as a top head snare micro-phone, and a Sennheiser MD 441placed on hi-hats. While these allturned out to be superfluous, Beattyhad some key comments about set up.He said that he uses the overheads torecord the cymbals and not the overallkit balance. As such, he suggestedplacing them so that they face the topsof the two crash cymbals, not at theedge where sound from the top andbottom clash. He backed off 2-3 inch-es on the snare and aimed the micro-phone at an angle to the head ratherthan downward.

For the hi-hats, he placed the 441 underneath to decrease leakage, andaimed them again at the body of thecymbal not the edge. By reversing thephase at the mixer, he was able toachieve a very tight, click like hi-hatsound reminiscent of disco, where Beat-ty got his start. He said that over theyears he has moved toward condensermicrophones, particularly small diaphragm ones for nearly all drum kits,because he finds that they respond bet-ter to equalization applied later.

After the kit was fully miked, thegroup listened to and considered eachcombination of techniques, traditionaland Beatty-style. By the end of thesession, it became clear that micro-phone choice really is secondary to theskill of the engineer in understandingthe instrument and the room in whichit is being played.

The section thanked Beatty for hisgenerous gift of time and education,and P. J. Melanson, who played thedrums throughout the session.

Jordan Tishler

Basics in Studio AudioOn January 18, 12 members and 33guests of the Singapore Section gath-

over the drummer’s shoulder.Beatty emphasized listening to the

kit as a microphone would, as amonaural source, i.e.: with a finger inone ear. However, whereas humanscan pick out a signal to pay attentionto in a loud environment, microphonesare not able to differentiate. The one-ear trick helps approximate what themicrophone will hear. He also sug-gested listening to the balance of thekit in various positions.

Since Beatty advocates putting microphones in position to get the bestbalance of the kit, rather than the moretraditional route of trying to recordonly what the microphone is pointingat, his placement choices — though abit unusual — are extremely effective.Beginning with the kick drum, an unported, double head drum with nodamping, Beatty applied a smalldamper (his coat) to the front head andbuilt a small tunnel out of a rug andmicrophone stand. He noted thatwhenever such a tunnel is used, thekey is to have it open at the back to allow for air movement and extensionof the bass frequencies.

Throughout the evening Beatty usedwhatever microphones were at hand,eschewing some of the more illustrious models in favor of the sim-pler ones. Although he used an AKG414 on the kick drum, Beatty’s mainmicrophone choice was a pair ofEarthworks QTC omnis, which heused to achieve a balance between thetoms and cymbals. Even the mostdoubtful of the group had to agree thatthe sound was amazing. He placed onemicrophone by the low tom at the lev-el of its rim point slightly up and toward the left crash cymbal. The sec-ond omni was placed between the tworack toms and pointed sideways at thehi-hats under the right crash cymbal.This was the only microphone thatneeded minor placement adjustmentduring the session.

Beatty then described a techniquehe calls the “Drummer’s Earrings,” inwhich a pair of Shure SM-81s areplaced approximately 12 inches fromthe drummers head on either side, fac-ing the kit. Beatty often modifies thisapproach by placing the microphonesfurther behind the drummer and rais-

OF THE

NEWS

SECTIONS


employed in a medical office, andforeground music, such as the invigo-rating pulse one might experience in ahealth club.

Historically, business audioproviders have delivered music bycassette, CD, or satellite. But now, Internet technology is making it possi-ble for businesses to have access to agreater selection and more direct delivery of audio. Using PCclient/server automation, audio con-tent can reside on a corporate serverand upon verification, be unlockedand played securely from a controlunit. Audio is compressed at a 10 to15:1 in Windows Media (WMA), or inother formats typically at 64-128 kb/srates. This means that very small filescan be moved easily, while still pro-viding full support for Digital RightsManagement (DRM). DRM guaran-tees that publishers and artists arecompensated when their copyrightedmusic is used for business purposes—a topic which spurred some debate.

Sheppard then described two refer-ence hardware designs that incorporateHDD, CD, and Ethernet connectivityas well as perform necessary decodingfunctionality. These units can also con-nect via a wireless network. For instance, using 802.11b, four to tenunits can be programmed to play dif-ferent audio selections to multiplelocations within one facility. Sheppardalso demonstrated the iPan-Win soft-ware, a music management applicationthat provides command and control ofunits for either corporate-wide, orregional use. Business audio systemsshould support ad insertion on the fly,said Sheppard. Half of today’s Internetradio stations insert ads using eitherHiwire or Lightningcast services.

In a discussion of clocks, Anthonyexplained the functions of variousclock types, including black burst,word clock, set-up clock, and timecode. He said a good quality clockcould directly affect the sound by reducing timing errors otherwiseknown as jitter.

After a brief discussion of micro-phones and how to select the right onefor the job, Anthony touched on thoseupcoming technologies that he feelsmight greatly affect the digital audiostudio. These include MLAN (MusicLAN, the audio over Firewire 1394technology by Yamaha), higher sam-ple rates, increasing-channel surroundsound, and the new media for audiosuch as DVD, which has the capabilityto also carry video.

The meeting ended after a robustquestion-and-answer session. The sec-tion thanked all three speakers forlending their expertise to this event.

Christopher Yap

Business Audio On March 26, 70 members of the LosAngeles Section met at the Burbank office of Dolby Laboratories to explore the topic of business audioand the Internet.

Guest presenter Dan Sheppard, co-founder and president of Audiorampbegan by asking the question: What isbusiness audio? In typical businessenvironments, such as hotels, retailstores, medical offices, health clubs,etc., such audio is used to accomplishvarious objectives, including maskingnoise, creating a pleasant atmosphere,delivering audio ads, relaxing employ-ees or creating a welcoming mood.There is background audio, like that

people in the studio. That said, Augustin also warned that openly heardnegative comments can work to dis-courage an actor and impede the session.

Pereira introduced the topic of pre-mastering by explaining its importanceas the last stage of a CD or media pro-duction after the mixdown process. After mixdown, premastering treats theoverall sound before the CD is pressed.“The (premastering) engineer marriesthe art of music with the science ofsound,” said Pereira. Thus, he mustunderstand the various musical styleshe is working with, and at the sametime, be sensitive to the requirementsof the producers and artists.

Reasons for premastering includeear fatigue, which is common aftercompleting a multitrack mixdown, andthe benefits that come with having another trained ear listen to the finalmix. He also described premasteringas the last ear to the musical project; alast resort for those final touches thatwill ensure a required final mix of theaudio before being pressed to CD.This process encompasses a whole listof tasks such as inserting the PQ code,balancing, stereo enhancement, level-ing tracks, dynamics processing andequalization. Pereira explained thatpremastering often improves acousticquality, dynamics, punch, presence,impact, warmth, transparency andclarity of a recording.

Anthony concluded the seminarwith a talk on delay in digital audio,AD/DA, processing and delay fromthe perspective of microphone place-ment. First, he described how to findthe delays being used in the setup, andhow to use the settings in the mixer toovercome some of the problems thismight cause.

Singapore Section members heard about the “Essential Basics in Studio Audio” at January meeting. photo by Cedric Teo

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be sure, there are practical problemswith Fielder’s approach. Introducingdrastic changes in the response of asound system can produce serious sideeffects. However, Fielder’s work, andthat of other world-class engineers,may well produce a greatly improvedapproach to EQ.

Paul Howard

Audio EducationThe Swiss Section celebrated a decadeof involvement in audio education onApril 8, by welcoming the successfulgraduates of the 2001 sound techni-cian exams, their teachers, committeemembers, and guests to a diploma cer-emony at the Kultur und Kongresszen-trum KKL in Lucerne.

The ceremony marked another yearof success of the sound techniciantraining program, which was estab-lished in 1992 by the Swiss Section’sAudio Education Committee. Thanksto countless hours of voluntary workfrom AES members and their col-leagues in the field, what began as adream in committee, became a realitywithin two years. In 1994, the first stu-dents began an 18-month course in licensed schools in Lausanne andZurich, and by 1995, the AES examin-ing committee organized the first setof exams. In 1996, after gainingofficial recognition from the SwissFederal government, the first diplomaswere awarded to successful candi-dates. Editor’s Note: Although this educational certification process hasbeen recognized in Switzerland, itwould not be viable in the U.S.

The program is now government-approved and supported by a growing

The meeting ended with a question-and-answer period followed by a dis-play of Crown amplifier products including the new JBL brand 6000 WClass-I car amplifier. The groupthanked Stanley for his presentation,Crown for providing the display, andRC Communications for the audio-visual equipment.

Bob Zurek

Fielder in SFLouis Fielder of Dolby Labs, spoke to45 sound professionals about “Analy-sis of Traditional and SubtractiveMethods of Room Equalization” atSan Francisco’s May meeting. He described an innovative approach toroom equalization, at Dolby Labs’ auditorium in San Francisco.

Fielder has devoted much of his lifeto engineering and acoustics. He holdsa master’s degree in acoustics. Tradi-tional EQ usually involves 1/3 octaveor parametric equalizers, employingarrays of 1st and 2nd-order filters.Such methods, when used by profes-sionals, usually give satisfactoryresults. Fielder has done pioneeringwork in acoustic measurements using-2 million-point FFTs (Fast FourierTransforms) at a sampling rate of 48kHz. Both frequency and time domains are measured. One strikingresult of his work is many sharp, nar-row peaks and dips in the amplituderesponse curves of most rooms. Suchvariations are often less than .1 Hzwide, and may have amplitudes of±55 dB. A 1/3 octave (or even a 1/6octave) EQ averages the energy inpeaks and dips, but usually can notcancel them due to their narrowness.Such high -Q variations in responsemay well be audible. Similar varia-tions usually also appear in the timedomain.

In Fielder’s room EQ method, theresults of a high-resolution FFT are inverted and inserted into the soundsystem signal chain. This smoothshigh-Q variations in amplitude response. Dereverberation is also a desired result of this method. Thetransfer function of the room is com-pared with a simple time delay, can-celing variations in time response. To

Sheppard concluded by advising theaudience that to properly reap thebenefits of greater selection and access to audio, business establish-ments installing the new systems mustpay attention to proper audio leveland balancing, microphone pagingfunctionality, and audio intelligibility,as well as providing a broadband Internet connection.

Chris Palmer

Power AmpsOn April 10, the Chicago Sectionhosted Gerald Stanley of Crown Inter-national, who provided an historicaloverview of the evolution of audiopower amplifiers, beginning withthermionic emission in the 1870sthrough the development of Class Iamplifiers in the late 1990s.

To chart the development of the amplifier, Stanley cited patents whichhighlight certain key inventions, suchas the first class-A push-pull amplifierin 1916 and the discovery of negativefeedback in the late 1920s. He alsoshared his observations regarding amplifier design, i.e., since technologyis not static, amplifier designs are onlylimited by the electron devices uponwhich they are based. He said that hebelieves obsolescence is a self-fulfill-ing prophecy, and that the value of aproduct in the customer’s eyes is whatultimately drives the design of a prod-uct. He also showed that most audio amplifiers are based on old technolo-gy, citing the invention of the firstclass-D amplifier in 1958 and the firstclass-H in 1967. Many designers arenot learning the lessons of the past andthus recreating the problems that amplifier designers experienced andsolved years ago, he said.

Stanley then shifted to a discussionof the state of amplifier design today,which is currently in a transition fromhighly dissipative to high efficiencydesigns, and from manual to comput-er-aided design tools. Stanley talkedabout the Class-I or Balanced CurrentAmplifiers that Crown is now produc-ing. The advantages of the interleavedClass-I amplifiers are that they requireno dead time, since the shoot-throughvoltage is eliminated.


Louis Fielder describes an innovativeapproach to room equalization at SanFrancisco’s May meeting.

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son Canadian Theatre (covering 1/3 ofthe area for small concerts), 180-degree concert mode (covering 2/3 ofthe area for larger concerts) and afourth configuration for trade shows.Giddings mentioned that the loud-speaker enclosures are made of plas-tic, which is better suited for arenasthan the higher priced wood boxedalternative, which might break downsooner.

Dave Clarke, director of audio engineering at Engineering Harmon-ics, talked about the firm’s involve-ment in the Walt Disney Concert Hallin Los Angeles. At a building cost of$240 million, this hall ranks amongone of the best in the world. The hallhouses three buildings: a concert hall,a pre-concert hall and amphitheatre.Thanks to modern technology and theInternet, Clarke was able to show aphoto taken that actual day of the pre-sentation at the construction site. Thebuilding is so large that a crane wasinstalled inside the structure to aid inmounting the billow elements of theceiling. Clarke displayed a 3-D anima-tion of the inside of the amphitheatreto show the group what the buildingwill look like when it is finished.

After a break, designer and networkspecialist Jeff Bamford talked aboutthe House of Commons CommitteeRoom Prototype project. This is ahuge undertaking to construct 22 newcommittee rooms at a cost of $22 mil-lion, and is estimated to be completedin 2010.

Bamford showed photos of the existing rooms and then a computeranimation of the proposed new rooms.For these, the company designed twopossible mockups for approval. Themockups made it possible to fine

ed the various audio-related laborato-ries owned and run by the university.The group was able to enjoy severalaudio demonstrations on buildingacoustics, voice recognition, sight-impairment aids and sound patternrecognition for industrial purposes.The meeting ended with formal sec-tion business.

Antonio J. de Oliveira

Engineering Harmonics The February meeting of the TorontoSection featured a multimedia demon-stration and review of four projectscurrently being undertaken by Engi-neering Harmonics, an engineeringfirm specializing in the design andproject management of sound, video,A/V, multimedia, control and commu-nication-based systems.

Company president Philip Giddingsstarted with a history of the company,which officially began in 1988 in hisbedroom. The company has sincegrown to eight people, and now handles contracts worth up to $240million. According to Giddings, thecompany has come so far that some ofthose first projects are so old they arenow being dismantled.

Giddings talked about a project he iscurrently undertaking to design theacoustics system for Mile One Stadi-um in St. John’s, Newfoundland, thesite of this year’s JUNO Awards.

The stadium is made up to two areas: a 6000-seat arena for hockey,tradeshows and a 60 000 sq. ft. convention center. According to Gid-dings, what makes the arena interest-ing is the building’s open architecture.There are four configurations withmultiple audio presets for sports, Mol-

number of employers, among themSwiss National Radio and TV. Theyspecifically require the course whenrecruiting new personnel. Many com-panies and organizations have gener-ously helped the program along theway by providing rooms, infrastruc-ture and equipment. Among them are:Studer Professional Audio, EmtecMagnetics, Weiss Engineering, Merg-ing Technologies, Gotham AG, J&CIntersonic AG, Radio Suisse Romandeand Stadttheater Bern.

At this year’s diploma ceremony,Markus Erne, AES vice president,Central Region, Europe, and MartinLachmann, chair of the examiningcommittee, awarded 19 diplomas tothe graduates of 2001. These youngprofessionals, together with graduatesfrom the past three exam sessions nowrepresent a community of nearly 100well-trained sound engineers.

Members of the examining commit-tee this year included: Gabriel Basso,Markus Erne, Stefan Giannini, MartinLachmann (president), Andreas Lit-manowitsch, Terry Nelson, PatrickRoe (vice president) and Marcel Zulauf. The next exam session will beheld in 2003.

Martin Lachmann

Portuguese Meet in PortoMore than 50 members of the Por-tuguese Section gathered on February26, at Faculdade de Engenharia at Por-to University in Porto for a series ofseminars on audio engineering. Topicsranged from acoustics to signal pro-cessing and included discussions ondigital radio, nonstandard audio appli-cations and cinema sound.

After lunch, section members visit-

Portuguese Sectionmembers attendedseminars on audio atPorto University inFebruary.

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dealers and technical support, which isessential for a theatrical organizationwith daily performances.

The new system consists of 5 UPA-1P and 2 UPA-2P arranged in variouscombinations into left, center, andright arrays. There are 14 UPM-1Psconfigured as delays in various loca-tions throughout the theater. A 650-Psubwoofer is generally placed upstagecenter for special effects, and two additional UPA-1Ps are available forspecial-purpose placement.

The loudspeaker management andcontrol system uses five BSS FDS-355 Omnidrive Compacts for a total of15 inputs and 25 outputs, all of whichare used among the loudspeaker arrays, delay zones, and special pur-pose loudspeakers. The automatedmixing system consists of two LCSLD-88 3-rackspace boxes, to create a16-in/16-out system, extendable to 32busses. LCS records and plays backconsole fader info, MIDI machinecontrol, panning, and many otherthings. It is also able to blend matrixchanges, cue-to-cue, either automati-cally or in any way the sound designerwishes. Playback comes from threeAkai DR-4 digital four tracks withexternal hard drives, and cues can beentered to LCS to delay a particularsound so it can be localized to anyplace in the theater.

During the second half of the meet-ing, LeGrand described the role of thesound designer. With the current advances in digital audio recording,editing, and playback devices,LeGrand said that the mechanicaltools are finally better able to serve asound designer’s more imaginativecreations. Digital audio can be editedquickly on a laptop or during rehearsalusing just-edited cues.

The biggest challenge, however, isstill to create music between scenes sothat they flow from one to another,and craft practical effects that soundreal. Sound design is always a com-promise, whether it is because ofequipment, time, or material limita-tions. The challenge is to make it workfor the audience, director, and actorsin the context of the play.

Dan Mortensen, Bill Droege andRyan Sorenson

tune the design and settle some ques-tions such as how many monitors andcameras to install, as well as confirmthe sight lines for the equipment. Thecompany is also putting together a testplan of over 100 tests on the systems.

Gary Tibshirani, director ofaudio/visual systems at EngineeringHarmonics, described his audio/videodesign project for the IBM Canadabuilding in Markham. The buildinghouses an executive briefing center,dividable lecture theater, training andfitness center, cafeteria, outdoor meet-ing space and over 60 meeting, board-room and video teleconferencingrooms. Implementing the project required a five-step process: schematicdesign, design development, contractdocumentation, bidding process andcontract administration. Specific design considerations included the assessment of network addressablecontrol and projection technology.

The section thanked EngineeringHarmonics; Peter Cook for introduc-tions; and Patricia Carr for organizingthe evening.

Michael Borlace

Theater Sound DesignOn December 10, the Pacific North-west Section met at the BagleyWright Theatre of the Seattle Reperto-ry Theater for a lecture on putting anew sound system into a successful regional theater. Bill Droege, headsound operator at Seattle RepertoryTheater for 11 years, Ryan Sorenson,current head sound operator for theSeattle Rep, and Steve LeGrand, free-lance sound designer for the SeattleRep, described the system hardwareand talked about the role of the sounddesigner in the theatrical process.

The 856-seat Bagley Wright The-ater, completed in 1983, is located onthe grounds of the Seattle Center. Thesound equipment was state-of-the art(circa 1981) and was showing clearsigns of fatigue over the last ten years.After a lengthy investigation of avail-able technology, the Rep chose a self-powered loudspeaker system fromMeyer Sound Laboratories. Meyerwas chosen in part because the compa-ny maintains a strong network of local

2002 October 5-8: 113th AESConvention, Los Angeles, CA,USA, Los Angeles Conven-tion, Los Angeles, CA. See p. 648 for more information.

2002 December 2-6: Joint Meet-ing: 144th Meeting of theAcoustical Society of Ameri-ca, 3rd Iberoamerican Con-gress on Acoustics, and 9thMexican Congress onAcoustics, Cancun, Mexico.Contact Melville, NY office,tel: 516-576-2360, fax: 516-576-2377, e-mail:[email protected].

2003 March 22-25: 114th AESConvention, RAI Conferenceand Exhibition Centre, Ams-terdam, the Netherlands. Seep. 648 for more information.

2003 May 23-25: AES 23rd In-ternational Confer-ence, “Signal Processing in Audio Recording and Reproduction,”Copenhagen, Denmark.Marienlyst Hotel, Helsingor,Copenhagen. For details see p. 648 or e-mail:[email protected].

2003 June 26-28: AES 24th International Conference,“Multichannel Audio: The NewReality,“ The Banff Centre,Banff, Alberta, Canada. For details and information: www.banffcentre.ca.

2003 October 10-13: AES 115thAES Convention, Jacob K.Javits Convention Center,New York, NY, USA. See p.648 for details.

2003 October 20-23: NAB Europe Radio Conference,Prague, Czech Republic. Contact Mark Rebholz (202) 429-3191 or e-mail: [email protected].

Upcoming Meetings

ABOUT PEOPLE…

John Murray, AES member, recently announced the opening of ProSonicSolutions, a manufacturer’s sales repre-

sentative firmserving the RockyMountain regionof the U.S. Murrayhas 26 years of experience in thesound industry. Hepromises to fosterlong-term relation-

ships with both the dealer and the manufacturer by offering his clientstechnical services beyond what one expects from a rep firm. He states thatthe company will go the extra step andoffer employee training, design assis-tance, and sound system tuning todealers in need.

Until 1991 Murray was professionalsound market development manager ofElectro-Voice. He also ran regionalsound seminars for them and was involved in the development of Altec’svariable intensity horns and EV’s stadium horns as well as other elec-tronic and acoustical products.Through 1998 he was a product man-ager at TOA Electronics, working onnew product development. He per-formed DSP-based acoustical mea-surements and signal processing on asingle laptop PC. From 1999 to 2000he ran MediaMatrix training and prod-uct documentation for the architecturalacoustics division of Peavey Electron-ics Corporation.

In 2000 he returned to TOA as fieldtraining specialist and now conductsTOA training sessions across thecountry. He is also an instructor for theLive Sound Workshop and NSCAExpo and a certified SIMM user andmember of the TEF Division of GoldLine Advisory Committee. The com-


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pany can be reached at www.prosonicsolutions.com. Murray canalso be reached in Woodland Park, COat tel: 719-332-3456.

JBL SPONSORS TOUR

AES sustaining member JBL has announced sponsorship of the upcom-ing U.S. summer tour of the seminalBritish rock group, The Who. Mem-bers of the Rock and Roll Hall of Fameand creators of the first rock opera,Tommy, The Who gained prominenceduring the “British Invasion” of the1960s and has since electrified listen-ers for over four decades.

The group performed at a benefitConcert for New York City after the9/11 tragedy at the World Trade Cen-ter. They will also perform in concertat Madison Square Garden in NewYork City in early August.

The company’s sponsorship pro-gram will include extensive nationaland local media advertising, includingtelevision, radio and print, along withsweepstakes and local market promo-tional activities with local radio, tele-vision and print media tie-ins. Soundservices will be provided by ClairBrothers Audio of Lititz, Pennsylva-nia. The concert audio system will fea-ture JBL drivers and components andhave in excess of 120 000 watts of am-plifier power.

The Who tour began June 28 in LasVegas at the Joint at the Hard RockHotel and Casino and includes a four-night stand at New York’s MadisonSquare Garden. The tour will concludeon August 31 at the Jones Beach Amphitheatre on Long Island, NewYork. Robert Plant, the former leadsinger of Led Zeppelin, will openmany of the East Coast shows, whileCounting Crows will support severalof the West Coast shows.

AdvertiserInternetDirectory*ACO Pacific Inc. ........................611, 615www.acopacific.com

*Audiomatica S.r.l. ..............................623www.audiomatica.com

BSWA Technology Co. Ltd. .............627www.bswa.com.cn

ETANI Electronics.............................635www.etani.co.jp

*SRS Labs Inc. ....................................609www.srslabs.com

*THAT Corp. ........................................619www.thatcorp.com

*AES Sustaining Member.


Secretary:Robert MasonTel./Fax +1 770 908 1833E-mail [email protected]

Treasurer:Leslie Jensen-LinkTel. +1 770 818 9180Fax +1 770 818 9179E-mail Leslie@mds,com

Chair:Kamyka GlennE-mail [email protected]

Vice Chair:Manuwade “A” KaruthanangE-mail [email protected]

Secretary:Chrissa Bowman7509 Savannah Grand Ave., #21204Winter Park, FL 32792Tel. +1 407 252 6177E-mail [email protected]

Treasurer:Devin PierceE-mail [email protected]

Faculty Advisor:Bill SmithAES Student SectionFull Sail Real World Education3300 University Blvd.Winter Park, FL 32793Tel. 800 679 0100E-mail [email protected]

Event Coordinator:Eric HunterE-mail [email protected]

Student Affairs:Tom JaminE-mail [email protected]

Webmaster:Erich NethertonE-mail [email protected]

Chair:Jordan TishlerE-mail [email protected]

Vice Chair:Eric ReuterE-mail [email protected]

Secretary:J. Nelson Chadderdonc/o Oceanwave Consulting, Inc.21 Old Town Rd.Beverly, MA 01915Tel. +1 978 232 9535 x201Fax +1 978 232 9537E-mail [email protected]

Treasurer:Joel GoldbergE-mail [email protected]

Chair:Bill GelhouseWMRG Studios Inc.P.O. Box 73Cheltenham, PA 19012-0073Tel. +1 215 635 4815Fax +1 215 782 8098E-mail [email protected]

Secretary:Rebecca MecuriP.O. Box 1166Philadelphia, PA 19105Tel. +1 609 895 1375E-mail [email protected]

Treasurer:Warren R. WilsonTel./Fax +1 610 935 0121E-mail [email protected]

Treasurer:Lavonya KnightTel. +1 757 728 4185E-mail [email protected]

Chair:Bil VornDickMountainside Productions6090 Fire Tower Rd.Nashville, TN 37212E-mail [email protected] Chair:Gary OldenbroekTel. +1 615 353 9105

Note that the apostrophe has been removed

from the spelling of the school’s name:Expression Center for New MediaSection (Student)Web site www.expression.edu

Chair:Michael StraussTel. +43 699 11309196E-mail [email protected]

Vice Chair:Holger HiebelTel. +43 699 10616133E-mail [email protected]

Secretary:Henning BosbachTel. +43 316 673726E-mail [email protected]

Treasurer:Stefan BayerTel. +43 676 6801786E-mail [email protected]

Chair:Jiri Schimmel

Faculty Advisor:Libor HusníkAES Studen SectionCzech Technical University at PragueTechnická 2, CZ 166 27 Prague 6, Czech RepublicTel. +420 2 2435 2115E-mail [email protected]

Faculty Sponsor:Andreas MeyerAES Student Sectionc/o Erich Thienhaus InstitutTonmeisterausbildung

Hochschule für Musik Detmold

Neustadt 22, DE-32756 Detmold,GermanyTel/Fax +49 5231 975639E-mail [email protected]

Section Overseas Contact:Katsuya (Vic) GohTel./Fax +81 466 81 0698 E-mail [email protected]

Japan Section

INTERNATIONAL REGION

Detmold Section (Student)

Czech Republic Student Section

Graz Section (Student)

CENTRAL REGION, EUROPE

Expression Center for New MediaSection (Student)

WESTERN REGION, USA/CANADA

Nashville Section

CENTRAL REGION, USA/CANADA

Hampton University Section (Student)

Philadelphia Section

Boston Section

Full Sail Real World EducationSection (Student)

Atlanta Section

EASTERN REGION, USA/CANADA

Updates and Corrections to the 2001/2002

AES INTERNATIONAL SECTIONS DIRECTORYThe following listing details updated and corrected information to the 2001/2002 AES International Sections Directory,as it appeared in the 2001 December issue of the Journal. Please note that only specific section information regardingthe particular office being updated or corrected is included here (e.g., Chairman, Vice Chairman, etc.).


Section symbols are: Adelaide (ADE), Alberta (AB), All-Russian State Institute of Cinematography (ARSIC), American RiverCollege (ARC), American University (AMU), Argentina (RA), Atlanta (AT), Austrian (AU), Ball State University (BSU),Belarus (BLS), Belgian (BEL), Belmont University (BU), Berklee College of Music (BCM), Berlin Student (BNS), Bosnia-Herzegovina (BA), Boston (BOS), Brazil (BZ), Brigham Young University (BYU), Brisbane (BRI), British (BR), Bulgarian(BG), Cal Poly San Luis Obispo State University (CPSLO), California State University–Chico (CSU), Carnegie MellonUniversity (CMU), Central German (CG), Central Indiana (CI), Chicago (CH), Chile (RCH), Citrus College (CTC), CogswellPolytechnical College (CPC), Colombia (COL), Colorado (CO), Columbia College (CC), Conservatoire de Paris Student(CPS), Conservatory of Recording Arts and Sciences (CRAS), Croatian (HR), Croatian Student (HRS), Czech (CR), CzechRepublic Student (CRS), Danish (DA), Danish Student (DAS), Darmstadt (DMS), Denver/student (DEN/S), Detmold Student(DS), Detroit (DET), District of Columbia (DC), Duquesne University (DU), Düsseldorf (DF), Expression Center for NewMedia (ECNM), Finnish (FIN), Fredonia (FRE), French (FR), Full Sail Real World Education (FS), Graz (GZ), Greek (GR),Hampton University (HPTU), Hong Kong (HK), Hungarian (HU), Ilmenau (IM), India (IND), Institute of Audio Research(IAR), Israel (IS), Italian (IT), Italian Student (ITS), Japan (JA), Kansas City (KC), Korea (RK), Lithuanian (LT), LongBeach/student (LB/S), Los Angeles (LA), Louis Lumière (LL), Malaysia (MY), McGill University (MGU), Melbourne (MEL),Mexican (MEX), Michigan Technological University (MTU), Middle Tennessee State University (MTSU), Moscow (MOS),Music Tech (MT), Nashville (NA), Netherlands (NE), Netherlands Student (NES), New Orleans (NO), New York (NY), NorthGerman (NG), Northeast Community College (NCC), Norwegian (NOR), Ohio University (OU), Pacific Northwest (PNW),Pennsylvania State University (PSU), Philadelphia (PHIL), Philippines (RP), Polish (POL), Portland (POR), Portugal (PT),Ridgewater College, Hutchinson Campus (RC), Romanian (ROM), SAE Nashville (SAENA), St. Louis (STL), St. Petersburg(STP), St. Petersburg Student (STPS), San Diego (SD), San Diego State University (SDSU), San Francisco (SF), SanFrancisco State University (SFU), Singapore (SGP), Slovakian Republic (SR), Slovenian (SL), South German (SG), SouthwestTexas State University (STSU), Spanish (SPA), Stanford University (SU), Strasbourg Student (SBS), Swedish (SWE), Swiss(SWI), Sydney (SYD), Taller de Arte Sonoro, Caracas (TAS), Technical University of Gdansk (TUG), The Art Institute of Seattle(TAIS), Toronto (TOR), Turkey (TR), Ukrainian (UKR), University of Cincinnati (UC), University of Hartford (UH), Universityof Javeriana, Bogota (UJ), University of Luleå-Piteå (ULP), University of Massachusetts–Lowell (UL), University of Miami(UOM), University of North Carolina at Asheville (UNCA), University of Southern California (USC), Upper Midwest (UMW),Uruguay (ROU), Utah (UT), Vancouver (BC), Vancouver Student (BCS), Venezuela (VEN), Vienna (VI), West Michigan (WM),William Paterson University (WPU), Worcester Polytechnic Institute (WPI), Wroclaw University of Technology (WUT),Yugoslavian (YU).

INFORMATION

MEMBERSHIP

Astor Marcus Alves de SilvaR. Giovanni da Conegliano 750, # 34B, SaoPaulo, SP 04186-020, Brazil (BZ)

Bejan E. Amini26861 Trabuco Rd. E220, Mission Viejo, CA92691 (LA)

Craig J. Anderson17154 Chatsworth St., Granada Hills, CA91344 (LA)

Marco Astolfivia Druento 16/bis, IT 10040 San Gillia (TO)Italy (IT)

Vladan BajicAudio Technica US, Inc., 1221 CommerceDr., Stow, OH 44224

Alain BeauvaisBlk. 485 Y10 , Chu Kang Rd. #08-08,787058 Singapore (SGP)

Frederic J. BroydeEXCEM, 12 Chemin des Hauts deClairefontaine, FR 78580, Maule, France(FR)

Owain J. Bryant# 3, The Cedars, 107 Cathedral Rd.,Pontcanna DE, Cardiff CF11 9PH, UK (BR)

Luiz Antonio Campos ReisRua do Progresso, 358 Ap. 32 Soledade,Recife, PE 50070-020, Brazil (BZ)

John R. Celli317 Oakley Ave., Long Branch, NJ 07740(NY)

Yizhong E. ChengYuanling 44-705, Hongil Rd., Shenzhen518028, Peoples Republic of China

Richard C. ClarkLong Communications, 961 Burke St.,Winston Salem, NC 27101

Arthur G. CoonsAGC Audio, P.O. Box 32, Pownal, VT 05261

Ian D. CorbettKansas City Kansas Community College,7250 State Ave., Kansas City, KS 66112(KC)

Jonathan CossuCinetrax Inc., 8033 Sunset Blvd. Ste. 400,Los Angeles, CA 90046 (LA)

Frank CostaParallel Solutions Inc., P.O. Box 1235,Commack, NY 11725 (NY)

Robert L. Coverston3310 Cary Ln., Indianapolis, IN 46235 (CI)

Martin DadicTurinina 2, HR 10010, Zagreb, Croatia (HR)

Bryan E. Davidson5 Valda Place, Baulkham Hills, NSW 2153New South Wales, Australia (SYD)

Ad De GrootSchoolhof 2, NL 3405 XL, Benschop,Netherlands (NE)

Leo De KlerkPagpauwoog 2, DK 3295 PG, S- Gravendeel,Denmark (DA)

Michel Delran6 rue de Brinville, FR 91750, Nainville lesRoches, France (FR)

Marisa T. Dery137 Park Dr. #39, Boston, MA 02215 (BOS)

Richard E. DrygasApplied Electronics Ltd., 5170 B TimberleaBlvd., Mississagua, OT L4W 2S5 Ontario,(TOR)

MEMBERS

These listings represent new membership according to grade.


MEMBERSHIP

INFORMATION

Frank A. Dunn1313 E. Bayview, Tempe, AZ 85283

Mauro FalconeFondazione Ugo Bordoni, via BaldassarreCastiglione 59, IT 00142, Rome, Italy (IT)

Shirley FangJMicron USA Technology, 43 CorporatePark Suite, Irvine, CA 92606 (LA)

Michael Feerick34 Levallyreagh Rd., Dromma CountyDown, BT25 2DG, Ireland

Martin J. Feldman646 W. Sheridan Rd., Chicago, IL 60613 (CH)

Isaac I. Fersternberg1111 River Rd., # B5, Edgewater, NJ 07020(NY)

John J. Freeman129A Ord St., San Fancisco, CA 94114 (SF)

Kenneth R. Freeman3 Valeria Circle, North Salem, NY 10560(NY)

Jean-Michel FroidevauxCh de la Crausaz 13, CH 1024, Ecublens,Switzerland (SWI)

John Frye3020 Willow Wisp Way, Cumming, GA30040 (AT)

Tak Chi Fung# G 21st/Flr., Opulent House AffluenceGarden, 33 Tsing Chung Rd., Tugn Mun,New Territories, Hong Kong (HK)

Michael GamtifteBang & Olufsen New Business A/S,Automotive, DK 7600, Struer, Denmark (DA)

Roland GauderDitzen Brunnerstr. 110, DE 71254,Ditzingen, Germany

Jonathan S. Goldstein28 Melville St., Staten Island, NY 10309 (NY)

Mark T. Grant2273 Italy Friend Rd., Penn Yan, NY 14527(NY)

James H. Greene2535 Scheaffer Rd. NE, Conyers, GA 30012-2608 (AT)

Scott C. GrinkerShure Communications Inc., 1335 BarclayBlvd., Buffalo Grove, IL 60089 (CH)

Jaap HaitsmaPhilips Research, Prof. Holtslaan 4 (WY 82),NL 5656 AA, Eindhoven, Netherlands (NE)

Mark S. Hall41 St. Nicholas Terrace, #19, New York, NY10027 (NY)

Kazuhiko HamadaFujitsu Ten Co. Ltd., Goshodohri 1-2-28,Hyogu-ku, Kobe-shi, Hyougo-ken 652-8510,Japan (JA)

Mark P. HansonArup Acoustics, 12/360 Elizabeth St.,Melbourne, VC 3000, Victoria, Australia(MEL)

Medi Hassine7067 Hawthorn Ave. #14, Hollywood, CA90028 (LA)

Gabriel HauserGundeldingerstrasse 145, CH 4053, Basel,Switzerland (SWI)

Raj Ali601 Bld. No. 26 Garden View Sco., BehindShantivan, Near Oshiwara Police Stn.,Andheri (W), India (IND)

Michael D. AmmonsSanmina-SCI M/S 260, P.O. Box 1000,Huntsville, AL 35807

Ketan Y. Ankelsaria9 Dev-Smruti N.S., Rd. No. 5, J.V.P.D.Scheme, Vile Parle, (W) Mumbai 400049,India (IND)

Takao Asayama1242 Socoro Ave., Sunnyvale, CA 94089 (SF)

Tom Blank5239 140th Ave. NW, Bellevue, WA 98005(PNW)

Georg BurdicekUntere Augartenstr. 5/4/13, AT 1020,Vienna, Austria (AU)

Roberto CanavesiStudio Oasis di Canavesi Roberto, via LuigiGoia 31, IT 27036, Mortara (PV), Italy (IT)

Nelson M. CardosoEst. do Capenha 275- Bl. 1 # 906, Rio deJaniero, RJ 22 740 040, Brazil (BZ)

Edoardo CiceriVia Trieste 76B, IT 21011, CasorateSempione (Varese), Italy (IT)

Eyal Cohen954 Black Mountain Ct., Los Altos, CA94024 (SF)

Kresimir DemoKozarceva 16A, HR 10 000, Zagreb, Croatia(HR)

Ivosevic DjuroPrisavlje 3, HR 10000, Zagreb, Croatia (HR)

Rainer Engel16 rue du 19 Mars 1962, FR 92230,Gennevilliers, France (FR)

Thomas Fine158 Overlook Dr., Brewster, NY 10509 (NY)

Normand Gagnon501 Forest, Mont-Saint Hilaire, QC J3H 5L5,Quebec, Canada

Willian L. Geary Jr.5205 Murray Rd., Chevy Chase, MD 20815(DC)

Andrew M. GrangerSony Music Studios London, 31-37 WhitfieldSt., London W1T 2SF, UK (BR)

Benjamin B. GuyDolby Laboratories Inc., Hammersly House,5-8 Warwick St., DE London, W1B 5LX,UK (BR)

Jeremy M. Balko10229 Eastern Ave. #102, Orlando, FL 32817(FS)

Raif Ballentine591 W. 13th St., Upland, CA 91786 (CTC)

Alexis Baskind79 rue Villiers de L’Isle Adam, FR 75020,Paris, France (CPS)

Steven L. Beckel51 Cherokee Dr., Windsor, PA 17366

Roman BeigelbeckFellnergasse 38, AT 1220, Vienna, Austria(VI)

Ronn Benharav36 Bartlett Ave., Lexington, MA 02420(BCM)

Jason L. Billops14410 Brook Forest Dr., Louisville, KY 40245

Eduardo F. BlanquiereSofie Blank Erf 22, NL 2907 BE, Capekke adYssel, Netherlands (NES)

Eric R. Block8195 Noblet, Davison, MI 48423

Jeffrey M. Bostwick27 Autumn Breeze Way, Winter Park, FL32792 (FS)

Charles Boykin203 Washington Blvd., # 3 South, Oak Park,IL 60302 (CC)

Vladimir M. BozicTomaska 3V, YU 11253, Belgrade,Yugoslavia

James G. Brian1311 Greenland Dr., #. E-5, Murfreesboro,TN 37130 (MTSU)

R. Andrew Brislin810 Marine St., Boulder, CO 80302

Brian J. Bruemmer7119 Bestview Terrace, Cincinnati, OH45230 (UC)

Roderick A. Brunton86 Morningside Dr., Edinburgh EH10 5NT,Scotland, UK

Robert S. Burke4710 SW 67th Ave. # H8, Miami, FL 33124(UOM)

Shannon L. Buroker2319 W. Clifton Ave., # 3, Cincinnati OH45219 (UC)

Andy D. Burton9 Beaumont Close, Wistaston, Crewe CW28BU, UK

Edgar Campos60 Picardy Ln., Wheeling, IL 60090 (CC)

Brian Casper1307 A Caldwell Ave., Nashville TN 37212(SAENA)

STUDENTS

ASSOCIATES

In Memoriam

Paul Wilbur Klipsch, leg-endary audio inventor andpioneer, passed away on May 5

in Hope, AR, at the age of 98.Klipsch was born in Elkhart,

IN, and spent his early yearsthere. The family later moved tothe Southwest, and Paul subse-quently entered New MexicoA&M College (now New MexicoState University) at Las Cruces,where he received a B.S.E.E. degree in 1926. After working forGeneral Electric (1926-1928) andthe Anglo-Chilean Nitrate Corpo-ration (Tocopilla, Chile, 1928-1931), he enrolled at StanfordUniversity and was awarded thegraduate degree in electrical engi-neering in 1934. It was at Stan-ford where he was influenced, aswere so many others, by the entre-preneurial and charismatic Freder-ick Terman.

After the Stanford years Paulworked for the Independent Explo-ration Company (Houston,TX, 1934-1936) and the Subterrex Company(Houston, 1937-1941). At the out-break of World War II he joined theU.S. Army and was assigned to theSouthwest Proving Grounds nearHope, AR. Here, his extensive back-ground in instrumentation, geo-physics and metrology were put towork. He left the army in 1945, even-tually attaining the rank of lieutenantcolonel.

Paul had shown an interest in audiofrom his early years, and by the late30s a design for a corner low-frequen-cy horn had jelled in his mind and inhis workshop. He eventually receiveda patent on the first iteration of the“K-horn” in 1945. With a few modifi-cations the traditional Klipschorn design emerged, and Paul decided toremain in Hope and set up a manufac-turing operation. The startup wasslow, and it wasn’t till the early 50sthat the high fidelity movement gotunderway. Even then, investmentcapital was hard to find, and Paul

developed Klipsch and Associates asa purely personal venture, setting upshop on the existing proving groundsite. A small but intensely loyal dealernetwork throughout the country keptthe company afloat.

All along, Paul had been hiringpromising engineering students forsummer work and acting as mentor tothem. I met Paul in 1954, but it wasnot until my tour of duty with theU. S. Army was over in 1958 that Ijoined his company. Paul had wantedto set up the “Klipschtape” division ofthe company to provide demo materi-al for his dealers, and I was asked tomanage it. It was a roller-coaster ridefor me, but somehow, with Paul at theConcertone (early tape recorder), wemanaged to produce about ten releas-es in two years, ranging from organ tojazz to choral works.

By 1958 I was, thanks to Paul’smentoring, enrolled at the Universityof Texas to study electrical engineer-ing. No other career in audio has beenas extended and as illustrious asPaul’s. He was the complete engineerwho could spin out meaningful num-bers and analyses describing just

about anything you presented tohim. His loves, in addition toacoustics, included trains and airplanes, and his patent contri-butions were in the fields ofacoustics, geophysics andfirearms. His honors include fellowships in the Audio Engi-neering Society, the Institute ofElectrical and Electronics Engineers, and the Acoustical Society of America, the SilverMedal of the AES, membershipsin Tau Beta Pi and Sigma Xi, induction into the Audio Hall ofFame (1983) and the Engineeringand Science Hall of Fame (1997),and a listing in Who’s Who inEngineering. In 1994, his almamater, New Mexico State Univer-sity, added his name to their Department of Electrical andComputer Engineering.

For many years, Paul’s presence atan AES Convention or a ConsumerElectronics Show was an invitation toobserve his criticism of anyone whopromised to break the laws of physicsor violate common sense. Paul alwayswalked away from such encounters ingood form, more as a teacher thancritic. Thanks to the addition ofskilled marketing, his company hasflourished over the past four decades,enjoying significant market share inthe fields of home theater, concertsound, and motion picture sound. Heis survived by his wife Valerie.

John M. EargleLos Angeles, CA

Editor’s Note: Although severalcolleagues contributed their reminis-cences of Klipsch, space limitationsprevent us from publishing all ofthem. Two appear below.

It was with great sadness that Ilearned of the passing of Paul W.Klipsch. Paul was one of the true leg-endary pioneers in audio. To many,including myself, he stood aboveeveryone else when it came to the

J. Audio Eng. Soc., Vol. 50, No. 7/8, 2002 July/Aug 639

Paul W. Klipsch 1904-2002

In Memoriam

understanding and creation of loud-speakers.

Klipsch was in his late thirtieswhen he began to study the problemof sound reproduction in a seriousway. He had always been interestedin radio and sound. In fact, he builthis first radio before the first commer-cial broadcasts. But prior to the1940s, he worked primarily as anengineer and geologist. Following another passion, trains, he supervisedthe maintenance of seven electric locomotives in Tocopilla, Chile, from1928-1931.

During World War II Paul was sta-tioned at the Southwest ProvingGrounds in Hope, Arkansas. It wasduring those years that the work thatwould make him a legend would begin to take shape. The initial workon his most famous loudspeaker, theKlipschorn, took several years. Thiswas an extremely clever design for ahorn-loaded loudspeaker in that thebass horn was folded around itselfand used the corner of a room as partof the loudspeaker. After the end ofthe war, Paul committed his life tobuilding loudspeakers, founding anew company called Klipsch and Associates in 1946.

By the end of his life, the Klip-schorn had become the most success-ful and long-lived product in the history of audio. Today, in 2002, over60 years after its initial design, theKlipschorn is still in production andstill unrivaled in sound reproductionfor the home.

Many who have written about Klip-sch’s life have noted that he inspirednumerous careers in audio. This iscertainly true. My own career is aprime example. The first time I hearda Klipschorn in the home of my nextdoor neighbor, I knew I had heardsomething extraordinary. What Ididn’t know is that my life would bechanged forever. It was another fewyears before I could save enough formy own Klipschorns, but once I hadthem, I could actually listen to musicwith the kind of satisfaction otherwisefound only in a live setting. Later,with Paul’s help, guidance and espe-

cially his loudspeaker systems, I wasable to bring this kind of quality tosymphony and ballet performanceswhere sound reinforcement was required.

Then in 1979, I founded my presentcompany and began my career in motion picture sound. Since then mywork has involved hundreds of suc-cessful installations and taken mecompletely around the world whileaccumulating over 1.2 million miles.Without Klipsch’s loudspeakers, Inever would have bothered to do anyof this, as nothing else would have orcould have inspired me so.

Though widely known for his bril-liance and sense of humor, to my surprise, Paul was also a controversialfigure. There have been audio engi-neers who have strongly disputedKlipsch’s design approaches as wellas his published writings. However,as far as I know, none of the dis-senters has produced a superior loud-speaker, let alone one that has stoodthe test of time for 60 years andcounting.

Not many know this, but it is hardto find a loudspeaker behind a moviescreen, or perhaps just about any horn-loaded loudspeaker that does not employ design features that were either invented by Paul Klipsch orenhanced by him. His patented K-5treble horn of 1951 has been widelycopied in one way or another. It wasthe first of what became known as theconstant directivity horn. Some 30years later, these horns became widelyused in movie theaters and in otherapplications, while Klipsch had already completed two more productdesign generations. In 1982, he designed a tweeter for my sound sys-tems that compensated for the cover-age angle distortions caused by moviescreens. It wasn’t for another 17 yearsthat other manufacturers followed suit.

In my view, this was typical of

Klipsch’s career1. He was years andoften decades ahead of his time. Heleft this world better than he found it.Lovers of music and sound aroundthe world will forever be in his debtand will forever enjoy their livesmore because of his great contribu-tions to loudspeaker design andstereophonic sound. For myself, I canonly say, I owe him everything.

John F. AllenNewton, MA

I want to express my sympathy forthe world’s loss of a truly gifted andunique genius, who made an indeliblemark on the world of audio and thelives of many, including my own.

My life and work has been guidedin some way—though obscure attimes— by Paul’s fascination with thereproduction of music ever since Iheard a neighbor’s “Shorthorn” inFayetteville, Arkansas. I was deter-mined to learn more about this “mystic” from Hope, who built loud-speakers of such uncanny realism.Learn I did, exchanged correspon-dence, visited frequently and wasasked to fill a vacancy in engineeringin November of 1974.

This was a different world. I alsobegan to realize how special my acceptance into this flock was. As thesaying goes, you had to pinch your-self to make sure you weren’t justdreaming.

I later discovered that many engi-neers would have given their right legfor my position with Paul. What a responsibility and performance I hadto live up to. As I heard Paul say ofhis acceptance of the AES SilverMedal Award in 1978, “I have stood on the shoulders of giants.” I amproud to have at least rubbed elbowswith one of those giants—PWK.

Gary C. GillumRidgedale, MO

640 J. Audio Eng. Soc., Vol. 50, No. 7/8, 2002 July/Aug

1 Anyone interested in reading more about Paul Klipsch may obtain the recently pub-lished book: Paul Wilbur Klipsch: the Life, the Legend, by Maureen Barrett andMichael Klementovich. The book is available directly from the publisher, RutledgeBooks, Inc.; 1 800 278-8533. ISBN: 1-58244-226-6. It is also available through book-stores as well as www.amazon.com and www.bn.com.

PROPOSED TOPICS FOR PAPERS

Please submit proposed title, abstract, and précisat www.aes.org/23rd_authors no later than 2002November 18. If you have any questions contact:

Signal Converter TopologiesPerceptual Aspects of ConversionDSP in RecordingMicrophone ArraysVocal ProcessingDSP in LoudspeakersCrossover Filters and EqualizationLoudspeaker ArraysIntelligent Power Management

SUBMISSION OF PAPERS SCHEDULEProposal deadline: 2002 November 18Acceptance emailed: 2003 January 3Paper deadline: 2003 February 18

Authors whose contributions have beenaccepted for presentation will receiveadditional instructions for submissionof their manuscripts.

PAPERS COCHAIRSJan Abildgaard Pedersen Lars Gottfried JohansenBang & Olufsen Aalborg UniversityStruer, Denmark Aalborg, Denmark

Email: [email protected]

Interfacing Loudspeaker and RoomRoom Adaptation, Control, and

EqualizationIntelligent SPL ControlCreating Space with DSPArtificial ReverberationSpatial Sound—Up/Down Conversion

of ChannelsNonlinear Signal Processing and

Modeling

AUDIO ENGINEERINGSOCIETY

CALL for PAPERSAES 23rd Conference, 2003

Copenhagen, Denmark

As signal processing becomes increasingly crucial in audio, the aim of this conference is to focus on signal processing at bothends of the electrical audio signal life cycle, namely the recording and reproduction stages. Signal processing in the recording pro-cess depends much on the way the signal is going to be reproduced, and signal processing in the reproduction stage must takeinto account processing during recording. New techniques and standards in digital audio merely emphasize this point. For this rea-son it has become necessary to consider the recording and reproduction setups, environments, and pieces of equipment as a sin-gle entity when using signal processing. This conference will bring together researchers and developers in all areas of signal pro-cessing for audio and will offer presentations by at least four invited speakers, as well as a large number of submitted papers.

The AES 23rd Conference Committee invites submission of technical papers for presentation at the conference in 2003 inCopenhagen. By 2002 November 18, a proposed title, 60- to 120-word abstract, and 500- to 750-word précis of the paper shouldbe submitted via the Internet to the AES 23rd Conference paper-submission site at www.aes.org/23rd_authors. You can visit thissite for more information and complete instructions for using the site anytime after 2002 September 18. The author’s information,title, abstract, and précis should be all submitted online. The précis should describe the work performed, methods employed, con-clusion(s), and significance of the paper. Titles and abstracts should follow the guidelines in Information for Authors atwww.aes.org/journal/con_infoauth.html. Acceptance of papers will be determined by the 23rd Conference review committee basedon an assessment of the abstract and précis.

Dates: May 23–25, 2003, Location: Helsingør, Copenhagen, DenmarkChair: Per Rubak, Aalborg University, Email: [email protected]



EASTERN REGION,USA/CANADA

Vice President:Jim Anderson12 Garfield PlaceBrooklyn, NY 11215Tel. +1 718 369 7633Fax +1 718 669 7631E-mail [email protected]

UNITED STATES OFAMERICA

CONNECTICUT

University of HartfordSection (Student)Howard A. CanistraroFaculty AdvisorAES Student SectionUniversity of HartfordWard College of Technology200 Bloomfield Ave.West Hartford, CT 06117-1599Tel. +1 860 768 5358Fax +1 860 768 5074 E-mail [email protected]

FLORIDA

Full Sail Real WorldEducation Section (Student)Chrissa BowmanAES Student SectionFull Sail Real World Education7509 Savannah Grand Ave.,

#21204Winter Park, FL 327922Tel. +1 407 252 6177E-mail [email protected]

University of Miami Section(Student)Ken Pohlmann, Faculty AdvisorAES Student SectionUniversity of MiamiSchool of MusicPO Box 248165Coral Gables, FL 33124-7610Tel. +1 305 284 6252Fax +1 305 284 4448E-mail [email protected]

GEORGIA

Atlanta SectionRobert Mason2712 Leslie Dr.Atlanta, GA 30345

Home Tel. +1 770 908 1833E-mail [email protected]

MASSACHUSETTS

Berklee College of MusicSection (Student)Eric Reuter, Faculty AdvisorBerklee College of MusicAudio Engineering Societyc/o Student Activities1140 Boylston St., Box 82Boston, MA 02215Tel. +1 978 443 7871Fax +1 978 443 7873E-mail [email protected]

Boston SectionJ. Nelson Chadderdonc/o Oceanwave Consulting, Inc.21 Old Town Rd.Beverly, MA 01915Tel. +1 978 232 9535 x201Fax +1 978 232 9537E-mail [email protected]

University ofMassachusetts–Lowell Section(Student)John Shirley, Faculty AdvisorAES Student ChapterUniversity of Massachusetts–LowellDept. of Music35 Wilder St., Ste. 3Lowell, MA 01854-3083Tel. +1 978 934 3886Fax +1 978 934 3034E-mail [email protected]

Worcester PolytechnicInstitute Section (Student) William MichalsonFaculty AdvisorAES Student SectionWorcester Polytechnic Institute100 Institute Rd.Worcester, MA 01609Tel. +1 508 831 5766E-mail [email protected]

NEW JERSEY

William Paterson UniversitySection (Student)David Kerzner, Faculty AdvisorAES Student SectionWilliam Paterson University300 Pompton Rd.Wayne, NJ 07470-2103Tel. +1 973 720 3198Fax +1 973 720 2217E-mail [email protected]

NEW YORK

Fredonia Section (Student)Bernd Gottinger, Faculty AdvisorAES Student SectionSUNY–Fredonia1146 Mason HallFredonia, NY 14063Tel. +1 716 673 4634Fax +1 716 673 3154E-mail [email protected]

Institute of Audio ResearchSection (Student)Noel Smith, Faculty AdvisorAES Student SectionInstitute of Audio Research 64 University Pl.New York, NY 10003Tel. +1 212 677 7580Fax +1 212 677 6549E-mail [email protected]

New York SectionRuss HammG Prime Limited1790 Broadway, Ste. 402New York, NY 10019Tel. +1 212 765 3415Fax +1 212 581 8938E-mail [email protected]

NORTH CAROLINA

University of North Carolinaat Asheville Section (Student)Wayne J. KirbyFaculty AdvisorAES Student SectionUniversity of North Carolina at

AshevilleDept. of MusicOne University HeightsAsheville, NC 28804Tel. +1 828 251 6487Fax +1 828 253 4573E-mail [email protected]

PENNSYLVANIA

Carnegie Mellon UniversitySection (Student)Thomas SullivanFaculty AdvisorAES Student SectionCarnegie Mellon UniversityUniversity Center Box 122Pittsburg, PA 15213Tel. +1 412 268 3351E-mail [email protected]

Duquesne University Section(Student)Francisco RodriguezFaculty AdvisorAES Student SectionDuquesne UniversitySchool of Music600 Forbes Ave.Pittsburgh, PA 15282Fax +1 412 396 5479E-mail [email protected] State UniversitySection (Student)Brian TuttleAES Penn State Student ChapterGraduate Program in Acoustics217 Applied Science Bldg.University Park, PA 16802Home Tel. +1 814 863 8282Fax +1 814 865 3119E-mail [email protected]

Philadelphia SectionRebecca MercuriP.O. Box 1166.Philadelphia, PA 19105Tel. +1 609 895 1375E-mail [email protected]

VIRGINIA

Hampton University Section(Student)Bob Ransom, Faculty AdvisorAES Student SectionHampton UniversityDept. of MusicHampton, VA 23668Office Tel. +1 757 727 5658,

+1 757 727 5404Home Tel. +1 757 826 0092Fax +1 757 727 5084E-mail [email protected]

WASHINGTON, DC

American University Section(Student)Benjamin TomassettiFaculty AdvisorAES Student SectionAmerican UniversityPhysics Dept.4400 Massachusetts Ave., N.W.Washington, DC 20016Tel. +1 202 885 2746Fax +1 202 885 2723E-mail [email protected]

District of Columbia SectionJohn W. ReiserDC AES Section Secretary

DIRECTORY

SECTIONS CONTACTS

The following is the latest information we have available for our sections contacts. If youwish to change the listing for your section, please mail, fax or e-mail the new informationto: Mary Ellen Ilich, AES Publications Office, Audio Engineering Society, Inc., 60 East42nd Street, Suite 2520, New York, NY 10165-2520, USA. Telephone +1 212 661 8528.Fax +1 212 661 7829. E-mail [email protected].

Updated information that is received by the first of the month will be published in thenext month’s Journal. Please help us to keep this information accurate and timely.

P.O. Box 169Mt. Vernon, VA 22121-0169Tel. +1 703 780 4824Fax +1 703 780 4214E-mail [email protected]

CANADA

McGill University Section(Student)John Klepko, Faculty AdvisorAES Student SectionMcGill UniversitySound Recording StudiosStrathcona Music Bldg.555 Sherbrooke St. W.Montreal, Quebec H3A 1E3CanadaTel. +1 450 465 0955E-mail [email protected]

Toronto SectionLee White26 Flaremore CrescentToronto, Ontario M2K 1V1CanadaTel. +1 416 222 2447Fax +1 416 222 8546E-mail [email protected]

CENTRAL REGION,USA/CANADA

Vice President:Jim KaiserMaster Mix1921 Division St.Nashville, TN 37203Tel. +1 615 321 5970Fax +1 615 321 0764E-mail [email protected]


INDIANA

Ball State University Section(Student)Michael Pounds, Faculty AdvisorAES Student SectionBall State UniversityMET Studios2520 W. BethelMuncie, IN 47306Tel. +1 765 285 5537Fax +1 765 285 8768E-mail [email protected]

Central Indiana SectionJames LattaSound Around6349 Warren Ln.Brownsburg, IN 46112Office Tel. +1 317 852 8379Fax +1 317 858 8105E-mail [email protected]

ILLINOIS

Chicago SectionRobert ZurekMotorola

2001 N. Division St.Harvard, IL 60033Tel. +1 815 884 1361Fax +1 815 884 2519E-mail [email protected]

Columbia College Section(Student)Dominique J. ChéenneFaculty AdvisorAES Student Section676 N. LaSalle, Ste. 300Chicago, IL 60610Tel. +1 312 344 7802Fax +1 312 482 9083

KANSAS

Kansas City SectionJim MitchellCustom Distribution Limited12301 Riggs Rd.Overland Park, KS 66209Tel. +1 913 661 0131Fax +1 913 663 5662

LOUISIANA

New Orleans SectionJoseph Doherty6015 Annunication St.New Orleans, LA 70118Tel. +1 504 891 4424Fax +1 504 891 6075

MICHIGAN

Detroit SectionTom ConlinDaimlerChryslerE-mail [email protected]

Michigan TechnologicalUniversity Section (Student)Andre LaRoucheAES Student SectionMichigan Technological

UniversityElectrical Engineering Dept.1400 Townsend Dr.Houghton, MI 49931Home Tel. +1 906 847 9324E-mail [email protected]

West Michigan SectionCarl HordykCalvin College3201 Burton S.E.Grand Rapids, MI 49546Tel. +1 616 957 6279Fax +1 616 957 6469E-mail [email protected]

MINNESOTA

Music Tech College Section(Student)Michael McKernFaculty AdvisorAES Student SectionMusic Tech College19 Exchange Street EastSaint Paul, MN 55101Tel. +1 651 291 0177Fax +1 651 291 [email protected]

Ridgewater College,Hutchinson Campus Section(Student)Dave Igl, Faculty AdvisorAES Student SectionRidgewater College, Hutchinson

Campus2 Century Ave. S.E.Hutchinson, MN 55350E-mail [email protected] Midwest SectionGreg ReiersonRare Form Mastering4624 34th Avenue SouthMinneapolis, MN 55406Tel. +1 612 327 [email protected]

MISSOURI

St. Louis SectionJohn Nolan, Jr.693 Green Forest Dr.Fenton, MO 63026Tel./Fax +1 636 343 4765

NEBRASKA

Northeast Community CollegeSection (Student)Anthony D. BeardsleeFaculty AdvisorAES Student SectionNortheast Community CollegeP.O. Box 469Norfolk, NE 68702Tel. +1 402 644 0581Fax +1 402 644 0650E-mail [email protected]

OHIO

Ohio University Section(Student)Erin M. DawesAES Student SectionOhio UniversityRTVC Bldg.9 S. College St.Athens, OH 45701-2979Home Tel. +1 740 597 6608E-mail [email protected]

University of CincinnatiSection (Student)Thomas A. HainesFaculty AdvisorAES Student SectionUniversity of CincinnatiCollege-Conservatory of MusicM.L. 0003Cincinnati, OH 45221Tel. +1 513 556 9497Fax +1 513 556 0202

TENNESSEE

Belmont University Section(Student)Wesley Bulla, Faculty AdvisorAES Student SectionBelmont UniversityNashville, TN 37212

Middle Tennessee StateUniversity Section (Student)

Doug Mitchell, Faculty AdvisorAES Student SectionMiddle Tennessee State University301 E. Main St., Box 21Murfreesboro, TN 37132Tel. +1 615 898 2553E-mail [email protected]

Nashville Section Tom EdwardsMTV Networks2806 Opryland Dr.Nashville, TN 37214Office Tel. +1 615 457 8009Fax +1 615 457 8855E-mail [email protected]

SAE Nashville Section (Student)Mark Martin, Faculty AdvisorAES Student Section7 Music Circle N.Nashville, TN 37203Tel. +1 615 244 5848Fax +1 615 244 3192E-mail [email protected]

TEXAS

Southwest Texas StateUniversity Section (Student)Mark C. EricksonFaculty AdvisorAES Student Section Southwest Texas State

University224 N. Guadalupe St.San Marcos, TX 78666Tel. +1 512 245 8451Fax +1 512 396 1169E-mail [email protected]

WESTERN REGION,USA/CANADA

Vice President:Bob MosesIsland Digital Media Group,

LLC26510 Vashon Highway S.W.Vashon, WA 98070Tel. +1 206 463 6667Fax +1 810 454 5349E-mail [email protected]


ARIZONA

Conservatory of TheRecording Arts and SciencesSection (Student)Glen O’HaraFaculty AdvisorAES Student Section Conservatory of The Recording

Arts and Sciences2300 E. Broadway Rd.Tempe, AZ 85282Tel. +1 480 858 9400, 800 562

6383 (toll-free)Fax +1 480 829 1332

SECTIONS CONTACTSDIRECTORY


[email protected]

CALIFORNIA

American River CollegeSection (Student)Eric Chun, Faculty AdvisorAES Student SectionAmerican River College Chapter4700 College Oak Dr.Sacramento, CA 95841Tel. +1 530 888 9440E-mail [email protected]

Cal Poly San Luis ObispoState University Section(Student)Jerome R. BreitenbachFaculty AdvisorAES Student SectionCalifornia Polytechnic State

UniversityDept. of Electrical EngineeringSan Luis Obispo, CA 93407Tel. +1 805 756 5710Fax +1 805 756 1458E-mail [email protected]

California State University–Chico Section (Student)Keith Seppanen, Faculty AdvisorAES Student SectionCalifornia State University–Chico400 W. 1st St.Chico, CA 95929-0805Tel. +1 530 898 5500E-mail [email protected]

Citrus College Section(Student)Gary Mraz, Faculty AdvisorAES Student SectionCitrus CollegeRecording Arts1000 W. Foothill Blvd.Glendora, CA 91741-1899Fax +1 626 852 8063

Cogswells PolytechnicalCollege Section (Student)Tim Duncan, Faculty SponsorAES Student SectionCogswell Polytechnical CollegeMusic Engineering Technology1175 Bordeaux Dr.Sunnyvale, CA 94089Tel. +1 408 541 0100, ext. 130Fax +1 408 747 0764E-mail [email protected]

Expression Center for NewMedia Section (Student)Scott Theakston, Faculty AdvisorAES Student SectionEx’pression Center for New

Media6601 Shellmount St.Emeryville, CA 94608Tel. +1 510 654 2934Fax +1 510 658 3414E-mail [email protected]

Long Beach City CollegeSection (Student)Nancy Allen, Faculty AdvisorAES Student SectionLong Beach City College

4901 E. Carson St.Long Beach, CA 90808Tel. +1 562 938 4312Fax +1 562 938 4118E-mail [email protected]

Los Angeles SectionAndrew Turner400 South Main St., #403Los Angeles, CA 90013Tel. +1 213 625 1790E-mail [email protected]

San Diego SectionJ. Russell Lemon2031 Ladera Ct.Carlsbad, CA 92009-8521Home Tel. +1 760 753 2949E-mail [email protected]

San Diego State UniversitySection (Student)John Kennedy, Faculty AdvisorAES Student SectionSan Diego State UniversityElectrical & Computer

Engineering Dept.5500 Campanile Dr.San Diego, CA 92182-1309Tel. +1 619 594 1053Fax +1 619 594 2654E-mail [email protected]

San Francisco SectionBrian E. Cheney3429 Morningside Dr.El Sobrante, CA 94803Tel. +1 510 222 4276Fax +1 510 232 3837E-mail [email protected]

San Francisco StateUniversity Section (Student)John Barsotti, Faculty AdvisorAES Student SectionSan Francisco State UniversityBroadcast and Electronic

Communication Arts Dept.1600 Halloway Ave.San Francisco, CA 94132Tel. +1 415 338 1507E-mail [email protected]

Stanford University Section(Student)Jay Kadis, Faculty AdvisorStanford AES Student SectionStanford UniversityCCRMA/Dept. of MusicStanford, CA 94305-8180Tel. +1 650 723 4971Fax +1 650 723 8468E-mail [email protected]

University of SouthernCalifornia Section (Student)Richard McIlveryFaculty AdvisorAES Student SectionUniversity of Southern California840 W. 34th St.Los Angeles, CA 90089-0851Tel. +1 213 740 3224Fax +1 213 740 3217E-mail [email protected]

COLORADO

Colorado SectionRobert F. MahoneyRobert F. Mahoney & Associates310 Balsam Ave.Boulder, CO 80304Tel. +1 303 443 2213Fax +1 303 443 6989E-mail [email protected] Section (Student)Roy Pritts, Faculty AdvisorAES Student SectionUniversity of Colorado at

DenverDept. of Professional StudiesCampus Box 162P.O. Box 173364Denver, CO 80217-3364Tel. +1 303 556 2795Fax +1 303 556 2335E-mail [email protected]

OREGON

Portland SectionTony Dal MolinAudio Precision, Inc.5750 S.W. Arctic Dr.Portland, OR 97005Tel. +1 503 627 0832Fax +1 503 641 8906E-mail [email protected]

UTAH

Brigham Young UniversitySection (Student)Jim Anglesey, Faculty AdvisorBYU-AES Student SectionSchool of MusicBrigham Young UniversityProvo, UT 84602Tel. +1 801 378 1299Fax +1 801 378 5973 (Music

Office)E-mail [email protected]

Utah SectionDeward Timothyc/o Poll Sound4026 S. MainSalt Lake City, UT 84107Tel. +1 801 261 2500Fax +1 801 262 7379

WASHI NGTON

Pacific Northwest SectionGary LouieUniversity of Washington

School of Music4522 Meridian Ave. N., #201Seattle, WA 98103Office Tel. +1 206 543 1218Fax +1 206 685 9499E-mail [email protected]

The Art Institute of SeattleSection (Student)David G. ChristensenFaculty AdvisorAES Student SectionThe Art Institute of Seattle2323 Elliott Ave.

Seattle, WA 98121-1622 Tel. +1 206 239 [email protected]

CANADA

Alberta SectionFrank LockwoodAES Alberta SectionSuite 404815 - 50 Avenue S.W.Calgary, Alberta T2S 1H8CanadaHome Tel. +1 403 703 5277Fax +1 403 762 6665E-mail [email protected]

Vancouver SectionPeter L. JanisC-Tec #114, 1585 BroadwayPort Coquitlam, B.C. V3C 2M7CanadaTel. +1 604 942 1001Fax +1 604 942 1010E-mail [email protected]

Vancouver Student SectionGregg Gorrie, Faculty AdvisorAES Greater Vancouver

Student SectionCentre for Digital Imaging and

Sound3264 Beta Ave.Burnaby, B.C. V5G 4K4, CanadaTel. +1 604 298 [email protected]

NORTHERN REGION,EUROPE

Vice President:Søren BechBang & Olufsen a/sCoreTechPeter Bangs Vej 15DK-7600 Struer, DenmarkTel. +45 96 84 49 62Fax +45 97 85 59 [email protected]

BELGIUM

Belgian SectionHermann A. O. WilmsAES Europe Region OfficeZevenbunderslaan 142, #9BE-1190 Vorst-Brussels, BelgiumTel. +32 2 345 7971Fax +32 2 345 3419

DENMARK

Danish SectionKnud Bank ChristensenSkovvej 2DK-8550 Ryomgård, DenmarkTel. +45 87 42 71 46Fax +45 87 42 70 10E-mail [email protected]




Danish Student SectionTorben Poulsen, Faculty AdvisorAES Student SectionTechnical University of DenmarkØrsted-DTU, Acoustic

TechnologyDTU - Building 352DK-2800 Kgs. Lyngby, DenmarkTel. +45 45 25 39 40Fax +45 45 88 05 77E-mail [email protected]

FINLANDFinnish SectionKalle KoivuniemiNokia Research CenterP.O. Box 100FI-33721 Tampere, FinlandTel. +358 7180 35452Fax +358 7180 35897E-mail [email protected]

NETHERLANDS

Netherlands SectionRinus BooneVoorweg 105ANL-2715 NG ZoetermeerNetherlandsTel. +31 15 278 14 71, +31 62

127 36 51Fax +31 79 352 10 08E-mail [email protected]

Netherlands Student SectionDirk FischerAES Student SectionGroenewegje 143aDen Haag, NetherlandsHome Tel. +31 70 [email protected]

NORWAY

Norwegian SectionJan Erik JensenNøklesvingen 74NO-0689 Oslo, NorwayOffice Tel. +47 22 24 07 52Home Tel. +47 22 26 36 13 Fax +47 22 24 28 06E-mail [email protected]

RUSSIA

All-Russian State Institute ofCinematography Section(Student)Leonid Sheetov, Faculty SponsorAES Student SectionAll-Russian State Institute of

Cinematography (VGIK)W. Pieck St. 3RU-129226 Moscow, RussiaTel. +7 095 181 3868Fax +7 095 187 7174E-mail [email protected]

Moscow SectionMichael LannieResearch Institute for

Television and RadioAcoustic Laboratory12-79 Chernomorsky bulvarRU-113452 Moscow, Russia

Tel. +7 095 2502161, +7 0951929011

Fax +7 095 9430006E-mail [email protected]. Petersburg SectionIrina A. AldoshinaSt. Petersburg University of

TelecommunicationsGangutskaya St. 16, #31RU-191187 St. Petersburg

RussiaTel. +7 812 272 4405Fax +7 812 316 1559E-mail [email protected]

St. Petersburg Student SectionNatalia V. TyurinaFaculty AdvisorProsvescheniya pr., 41, 185RU-194291 St. Petersburg, RussiaTel. +7 812 595 1730Fax +7 812 316 [email protected]

SWEDEN

Swedish SectionMikael OlssonAudio Data LabKatarinavägen 22SE-116 45 Stockholm, SwedenTel. +46 8 30 29 98Fax +46 8 641 67 91E-mail [email protected]

University of Luleå-PiteåSection (Student)Lars Hallberg, Faculty SponsorAES Student SectionUniversity of Luleå-PiteåSchool of MusicBox 744S-94134 Piteå, SwedenTel. +46 911 726 27Fax +46 911 727 10E-mail [email protected]

UNITED KINGDOM

British SectionHeather LaneAudio Engineering SocietyP.O. Box 645Slough GB-SL1 8BJUnited KingdomTel. +44 1628 663725Fax +44 1628 667002E-mail [email protected]

CENTRAL REGION,EUROPE

Vice President:Markus ErneScopein ResearchSonnmattweg 6CH-5000 Aarau, SwitzerlandTel. +41 62 825 09 19Fax +41 62 825 09 [email protected]

AUSTRIA

Austrian SectionFranz LechleitnerLainergasse 7-19/2/1AT-1238 Vienna, AustriaOffice Tel. +43 1 4277 29602Fax +43 1 4277 9296E-mail [email protected]

Graz Section (Student)Robert Höldrich, Faculty SponsorInstitut für Elektronische Musik

und AkustikInffeldgasse 10AT-8010 Graz, AustriaTel. +43 316 389 3172Fax +43 316 389 3171E-mail [email protected]

Vienna Section (Student)Jürg Jecklin, Faculty SponsorVienna Student SectionUniversität für Musik und

Darstellende Kunst WienInstitut für Elektroakustik und

Experimentelle MusikRienösslgasse 12AT-1040 Vienna, AustriaTel. +43 1 587 34 78Fax +43 1 587 34 78 20E-mail [email protected]

CZECH REPUBLIC

Czech SectionJiri OcenasekDejvicka 36CZ-160 00 Prague 6Czech Republic Home Tel. +420 2 24324556E-mail [email protected]

Czech Republic StudentSectionLibor Husník, Faculty AdvisorAES Student SectionCzech Technical University atPragueTechnická 2, CZ-116 27 Prague 6Czech RepublicTel. +420 2 2435 2115E-mail [email protected]

GERMANY

Berlin Section (Student)Bernhard Güttler Zionskirchstrasse 14DE-10119 Berlin, GermanyTel. +49 30 4404 72 19Fax +49 30 4405 39 03E-mail [email protected]

Central German SectionErnst-Joachim VölkerInstitut für Akustik und

BauphysikKiesweg 22-24DE-61440 Oberursel, GermanyTel. +49 6171 75031Fax +49 6171 85483E-mail [email protected]

Darmstadt Section (Student)G. M. Sessler, Faculty SponsorAES Student Section

Technical University ofDarmstadt

Institut für ÜbertragungstechnikMerkstr. 25DE-64283 Darmstadt, GermanyTel. +49 6151 [email protected]

Detmold Section (Student)Andreas Meyer, Faculty SponsorAES Student Sectionc/o Erich Thienhaus InstitutTonmeisterausbildung

Hochschule für Musik Detmold

Neustadt 22, DE-32756Detmold, GermanyTel/Fax +49 5231 975639E-mail [email protected]

Düsseldolf Section (Student)Ludwig KuglerAES Student SectionBilker Allee 126DE-40217 Düsseldorf, GermanyTel. +49 211 3 36 80 [email protected]

Ilmenau Section (Student)Karlheinz BrandenburgFaculty SponsorAES Student SectionInstitut für MedientechnikPF 10 05 65DE-98684 Ilmenau, GermanyTel. +49 3677 69 2676Fax +49 3677 69 1255E-mail [email protected]

North German SectionReinhard O. SahrEickhopskamp 3DE-30938 Burgwedel, GermanyTel. +49 5139 4978Fax +49 5139 5977E-mail [email protected]

South German SectionGerhard E. PicklappLandshuter Allee 162DE-80637 Munich, GermanyTel. +49 89 15 16 17Fax +49 89 157 10 31E-mail [email protected]

HUNGARY

Hungarian SectionFerenc György TakácsSzellö u. 2. VII. 18.HU-1035 Budapest, HungaryHome Tel. +36 1 368 47 70Office Tel. +36 1 463 20 47Fax +36 1 463 32 66E-mail [email protected]

LITHUANIA

Lithuanian SectionVytautas J. StauskisVilnius Gediminas Technical

UniversitySauletekio al. 11LT-2040 Vilnius, LithuaniaTel. +370 2 700 492


Fax +370 2 700 498E-mail [email protected]

POLAND

Polish SectionJan A. AdamczykUniversity of Mining and

MetallurgyDept. of Mechanics and

Vibroacousticsal. Mickiewicza 30PL-30 059 Cracow, PolandTel. +48 12 617 30 55Fax +48 12 633 23 14E-mail [email protected]

Technical University of GdanskSection (Student)Krzysztof KakolAES Student Section Technical University of GdanskSound Engineering Dept.ul. Narutowicza 11/12PL-809 52 Gdansk, PolandHome Tel. +48 501 058 279Fax +48 58 3471114E-mail [email protected]

Wroclaw University ofTechnology Section (Student)Andrzej B. DobruckiFaculty SponsorAES Student SectionInstitute of Telecommunications

and AcousticsWroclaw University of

TechnologyWybrzeze Wyspianskiego 27PL-503 70 Wroclaw, PolandTel. +48 71 320 30 68Fax +48 71 320 31 89E-mail [email protected]

REPUBLIC OF BELARUS

Belarus SectionValery ShalatoninBelarusian State University of

Informatics and Radioelectronics

vul. Petrusya Brouki 6BY-220027 MinskRepublic of BelarusTel. +375 17 239 80 95Fax +375 17 231 09 14E-mail [email protected]

SLOVAK REPUBLIC

Slovakian Republic SectionRichard VarkondaCentron Slovakia Ltd.Podhaj 107SK-841 03 BratislavaSlovak RepublicTel. +421 7 6478 0767Fax. +421 7 6478 [email protected]

SWITZERLAND

Swiss Section

Attila KaramustafaogluAES Swiss SectionSonnmattweg 6CH-5000 AarauSwitzerlandE-mail [email protected]

UKRAINE

Ukrainian SectionValentin AbakumovNational Technical University

of UkraineKiev Politechnical InstitutePolitechnical St. 16Kiev UA-56, UkraineTel./Fax +38 044 2746093

SOUTHERN REGION,EUROPE

Vice President:Daniel ZalayConservatoire de ParisDept. SonFR-75019 Paris, FranceOffice Tel. +33 1 40 40 46 14Fax +33 1 40 40 47 [email protected]

BOSNIA-HERZEGOVINA

Bosnia-Herzegovina SectionJozo TalajicBulevar Mese Selimovica 12BA-71000 SarajevoBosnia–HerzegovinaTel. +387 33 455 160Fax +387 33 455 163E-mail [email protected]

BULGARIA

Bulgarian SectionKonstantin D. KounovBulgarian National RadioTechnical Dept.4 Dragan Tzankov Blvd. BG-1040 Sofia, BulgariaTel. +359 2 65 93 37, +359 2

98 52 46 01Fax +359 2 963 1003E-mail [email protected]

CROATIA

Croatian SectionSilvije StamacHrvatski RadioPrisavlje 3HR-10000 Zagreb, CroatiaTel. +385 1 634 28 81Fax +385 1 611 58 29E-mail [email protected]

Croatian Student SectionHrvoje DomitrovicFaculty Advisor

AES Student SectionFaculty of Electrical

Engineering and ComputingDept. of Electroaocustics (X. Fl.)Unska 3HR-10000 Zagreb, CroatiaTel. +385 1 6129 640Fax +385 1 6129 [email protected]

FRANCE

Conservatoire de ParisSection (Student)Alessandra Galleron36, Ave. ParmentierFR-75011 Paris, FranceTel. +33 1 43 38 15 94

French SectionMichael WilliamsIle du Moulin62 bis Quai de l’Artois FR-94170 Le Perreux sur

Marne, FranceTel. +33 1 48 81 46 32Fax +33 1 47 06 06 48E-mail [email protected]

Louis Lumière Section(Student)Alexandra Carr-BrownAES Student SectionEcole Nationale Supérieure

Louis Lumière7, allée du Promontoire, BP 22FR-93161 Noisy Le Grand

Cedex, FranceTel. +33 6 18 57 84 [email protected]

GREECE

Greek SectionSoterios SalamourisRoister Sapfous St. 145 GR-17675 Kallithea, GreeceTel. +30 1 9599088, +30 1

9522283Fax +30 1 9582730E-mail [email protected]

ISRAEL

Israel SectionBen Bernfeld Jr.H. M. Acustica Ltd.1/11 Ha’alumim St.IL-46308 Herzlia, IsraelTel. +972 9 9574448Fax +972 9 9574254E-mail [email protected]

ITALY

Italian SectionCarlo Perrettac/o AES Italian SectionPiazza Cantore 10IT-20134 Milan, ItalyTel. +39 338 9108768

Fax +39 02 58440640E-mail [email protected]

Italian Student SectionFranco Grossi, Faculty AdvisorAES Student SectionViale San Daniele 29 IT-33100 Udine, ItalyTel. +39 [email protected]

PORTUGAL

Portugal SectionRui Miguel Avelans CoelhoR. Paulo Renato 1, 2APT-2745-147 Linda-a-VelhaPortugalTel. +351 214145827E-mail [email protected]

ROMANIA

Romanian SectionMarcia TaiachinRadio Romania60-62 Grl. Berthelot St.RO-79756 Bucharest, RomaniaTel. +40 1 303 12 07Fax +40 1 222 69 19

SLOVENIA

Slovenian SectionTone SeliskarRTV SlovenijaKolodvorska 2SI-1550 Ljubljana, SloveniaTel. +386 61 175 2708Fax +386 61 175 2710E-mail [email protected]

SPAIN

Spanish SectionJuan Recio MorillasSpanish SectionC/Florencia 14 3oDES-28850 Torrejon de Ardoz

(Madrid), SpainTel. +34 91 540 14 03E-mail [email protected]

TURKEY

Turkish SectionSorgun AkkorSTDSelamicesme, Gulden sok. 2/2Kadikoy TR-81060, IstanbulTurkeyTel. +90 216 4671814Fax +90 216 4671815E-mail [email protected]

YUGOSLAVIA

Yugoslavian Section Tomislav Stanojevic




Sava centreM. Popovica 9YU-11070 Belgrade, YugoslaviaTel. +381 11 311 1368Fax +381 11 605 [email protected]

LATIN AMERICAN REGION

Vice President:Mercedes OnoratoTalcahuano 141Buenos Aires, ArgentinaTel./Fax +5411 4 375 [email protected]

ARGENTINA

Argentina SectionMercedes Onorato Talcahuano 141Buenos Aires, ArgentinaTel./Fax +5411 4 375 0116E-mail [email protected]

BRAZIL

Brazil SectionRosalfonso BortoniRua Carlos Machado, 164Polo Rio Cine Video, Barra da

TijucaRio de Janeiro, RJ-Brazil22775-042Tel./Fax +55 21 2421 0112Mobile +55 35 9983 0533E-mail [email protected]

CHILE

Chile SectionAlejandro Soto de ValleUniversidad Tecnológica

Vicente Pérez RosalesBrown Norte 290Nunoa, Santiago de ChileTel. +56 2 274 5432Fax +56 2 223 8825

COLOMBIA

Colombia SectionTony Penarredonda CaraballoCarrera 51 #13-223Medellin, ColombiaTel. +57 4 265 7000Fax +57 4 265 2772E-mail [email protected]

MEXICO

Mexican SectionJavier Posada Div. Del Norte #1008Col. Del ValleMexico, D.F. MX-03100MexicoTel. +52 5 669 48 79Fax +52 5 543 60 37E-mail [email protected]

URUGUAY

Uruguay SectionRafael AbalSondor S.A.Calle Rio Branco 1530C.P. UY-11100 MontevideoUruguayTel. +598 2 91 26 70, +598 2 92

53 88Fax +598 2 92 52 72E-mail [email protected]

VENEZUELA

Taller de Arte Sonoro,Caracas Section (Student)Carmen Bell-Smythe de LealFaculty AdvisorAES Student SectionTaller de Arte SonoroAve. Rio de Janeiro Qta. Tres PinosChuao, VE-1061 CaracasVenezuelaTel. +58 14 9292552Tel./Fax +58 2 9937296E-mail [email protected]

Venezuela SectionElmar LealAve. Rio de JaneiroQta. Tres PinosChuao, VE-1061 CaracasVenezuelaTel. +58 14 9292552Tel./Fax +58 2 9937296E-mail [email protected]

INTERNATIONAL REGION

Vice President:Neville Thiele10 Wycombe St.Epping, NSW AU-2121,AustraliaTel. +61 2 9876 2407Fax +61 2 9876 2749E-mail [email protected]

AUSTRALIA

Adelaide SectionDavid MurphyKrix Loudspeakers14 Chapman Rd.Hackham AU-5163South AustraliaTel. +618 8 8384 3433Fax +618 8 8384 3419E-mail [email protected]

Brisbane SectionDavid RingroseAES Brisbane SectionP.O. Box 642Roma St. Post OfficeBrisbane, Qld. AU-4003, AustraliaOffice Tel. +61 7 3364 6510E-mail [email protected]

Melbourne SectionGraham J. HaynesP.O. Box 5266Wantirna South, VictoriaAU-3152, AustraliaTel. +61 3 9887 3765Fax +61 3 9887 [email protected] SectionHoward JonesAES Sydney SectionP.O. Box 766Crows Nest, NSW AU-2065AustraliaTel. +61 2 9417 3200Fax +61 2 9417 3714

HONG KONG

Hong Kong SectionHenry Ma Chi FaiHKAPA, School of Film and

Television1 Gloucester Rd. Wanchai, Hong KongTel. +852 2584 8824Fax +852 2588 1303E-mail [email protected]

INDIA

India SectionAvinash OakWestern Outdoor Media Tech.16, Mumbai Samachar MargMumbai IN-400 023, IndiaTel. +91 22 2046181Fax +91 22 2043038E-mail [email protected]

JAPAN

Japan SectionKatsuya (Vic) Goh2-15-4 Tenjin-cho, Fujisawa-shiKanagawa-ken 252-0814, JapanTel./Fax +81 466 81 0698 E-mail [email protected]

KOREA

Korea SectionSeong-Hoon KangTaejeon Health Science CollegeDept. of Broadcasting

Technology77-3 Gayang-dong Dong-guTaejeon, Korea Tel. +82 42 630 5990Fax +82 42 628 1423E-mail [email protected]

MALAYSIA

Malaysia SectionC. K. Ng King Musical Industries

Sdn BhdLot 5, Jalan 13/2MY-46200 Kuala LumpurMalaysiaTel. +603 7956 1668Fax +603 7955 4926E-mail [email protected]

PHILIPPINES

Philippines SectionDario (Dar) J. Quintos125 Regalia Park TowerP. Tuazon Blvd., CubaoQuezon City, PhilippinesTel./Fax +63 2 4211790, +63 2

4211784E-mail [email protected]

SINGAPORE

Singapore SectionP. V. Anthonyc/o MIND & MEDIA1G Paya Lebar Rd. SG-408999 SingaporeRepublic of SingaporeTel. +65 0 547 1067Fax +65 0 743 0096E-mail [email protected]

Chair:Scott CannonStanford University Section (AES)P.O. Box 15259Stanford, CA 94309Tel. +1 650 346 4556Fax +1 650 723 8468E-mail [email protected]

Vice Chair:Dell HarrisHampton University Section(AES)125A Mariners CoveHampton, VA 23669Tel +1 757 723 4374E-mail [email protected]

Chair:Blaise ChabanisConservatoire de Paris

(CNSMDP) Student Section (AES)

14, rue de la FaisanderieFR-77200 Torcy, FranceTel. +336 62 15 29 97E-mail [email protected]

Vice Chair:Werner de BruijnThe Netherlands Student

Section (AES)Korvezeestraat 541NL-2628 CZ DelftThe NetherlandsHome Tel. +31 15 2622995Office Tel. +31 15 [email protected]

EUROPE/INTERNATIONALREGIONS

NORTH/SOUTH AMERICA REGIONS

STUDENT DELEGATEASSEMBLY



AES CONVENTIONS AND CON

22nd International ConferenceEspoo, Finland“Virtual, Synthetic, andEntertainment Audio”Date: 2002 June 15–17Location: Helsinki Universityof TechnologyEspoo, Finland

The latest details on the following events are posted on the AES Website: http://www.aes.org

Convention chair:Floyd TooleHarman International8500 Balboa Blvd.Northridge, CA 91329, USATelephone: +1 818 895 5761Fax: +1 818 893 7139Email: [email protected]

Papers cochair: John StrawnS Systems, Inc.

Telephone: +1 415 927 8856Email: [email protected]

Papers cochair:Eric BenjaminDolby Laboratories, Inc.Telephone: +1 415 558 0236Email: [email protected]

Exhibit information:Chris PlunkettTelephone: +1 212 661 8528

113th ConventionLos Angeles, California, USADate: 2002 October 5–8Location: Los AngelesConvention Center,Los Angeles, California, USA

Conference cochairs:Jyri Huopaniemi and Nick ZacharovNokia Research CenterSpeech and Audio SystemsLaboratoryEmail: [email protected]

Papers chair: Vesa VälimäkiHelsinki University of Technology

Lab. of Acoustics and Audio SignalProcessingP. O. Box 3000, FIN-02015 HUTEspoo, FinlandFax: +358 9 460 224Email: [email protected]

Call for papers: Vol. 49, No. 9,p. 852 (2001 September)

Convention chair:Peter A. SwarteP.A.S. Electro-AcousticsGraaf Adolfstraat 855616 BV EindhovenThe NetherlandsTelephone: +31 40 255 0889Email: [email protected]

Papers chair: Ronald M. AartsVice Chair: Erik LarsenDSP-Acoustics & Sound

ReproductionPhilips Research Labs, WY81Prof. Hostlaan 45656 AA Eindhoven, TheNetherlandsTelephone: +31 40 274 3149Fax: +31 40 274 3230Email: [email protected]

114th ConventionAmsterdam, The NetherlandsDate: 2003 March 22–25Location: RAI Conference and Exhibition CentreAmsterdam, The Netherlands

Conference chair:Theresa LeonardThe Banff CentreBanff, CanadaEmail: [email protected]

24th International ConferenceBanff, CanadaDate: 2003 June 26–28Location: The Banff Centre,Banff, Alberta, Canada

Conference chair:Nickolay I. IvanovBaltic State Technical UniversityTelephone: +7 812 1101573Fax: +7 812 3161559Email: [email protected]

Scientific Committee chair:Irina A. Aldoshina

St. Petersburg University ofTelecommunicationsTelephone: +7 812 2724405Fax: +7 812 3161559Email: [email protected]

Papers chair: Natalia V. TyurinaBaltic State Technical University1st Krasnoarmeyskaya Str. 1

21st International ConferenceSt. Petersburg, Russia“Architectural Acoustics andSound Reinforcement”Date: 2002 June 1–3Location: Hotel MoscowSt. Petersburg, Russia

23rd International ConferenceCopenhagen, Denmark“Signal Processing in AudioRecording and Reproduction”Date: 2003 May 23–25Location: Marienlyst Hotel,Helsingør, Copenhagen,Denmark

115th ConventionNew York, NY, USADate: 2003 October 10–13Location: Jacob K. JavitsConvention Center, New York, New York, USA

Conference chair:Per RubakAalborg UniversityFredrik Bajers Vej 7 A3-216DK-9220 Aalborg ØDenmarkTelephone: +45 9635 8682Email: [email protected]

Papers cochair: Jan Abildgaard PedersenBang & Olufsen A/SPeter Bangs Vej 15P.O. box 40,DK-7600 StruerPhone: +45 9684 1122E-mail: [email protected]

2002St. Petersburg,

Russia

Espoo

2002

Los Angeles

2003Amsterdam

Banff2003

NEW YORK2003

2003Copenhagen

Fax: +1 212 682 0477Email: [email protected]

Call for papers: Vol. 50, No. 1/2,p. 100 (2002 January/February)

Call for workshops participants: Vol. 50, No. 3, p. 206 (2002 March)

Convention preview: This issue,pp. 606–628 (2002 July/August)

FERENCESPresentationManuscripts submitted should betypewritten on one side of ISO size A4(210 x 297 mm) or 216-mm x 280-mm(8.5-inch x 11-inch) paper with 40-mm(1.5-inch) margins. All copies includingabstract, text, references, figure captions,and tables should be double-spaced.Pages should be numbered consecutively.Authors should submit an original plustwo copies of text and illustrations.ReviewManuscripts are reviewed anonymouslyby members of the review board. After thereviewers’ analysis and recommendationto the editors, the author is advised ofeither acceptance or rejection. On thebasis of the reviewers’ comments, theeditor may request that the author makecertain revisions which will allow thepaper to be accepted for publication.ContentTechnical articles should be informativeand well organized. They should citeoriginal work or review previous work,giving proper credit. Results of actualexperiments or research should beincluded. The Journal cannot acceptunsubstantiated or commercial statements.OrganizationAn informative and self-containedabstract of about 60 words must beprovided. The manuscript should developthe main point, beginning with anintroduction and ending with a summaryor conclusion. Illustrations must haveinformative captions and must be referredto in the text.

References should be cited numerically inbrackets in order of appearance in thetext. Footnotes should be avoided, whenpossible, by making parentheticalremarks in the text.

Mathematical symbols, abbreviations,acronyms, etc., which may not be familiarto readers must be spelled out or definedthe first time they are cited in the text.

Subheads are appropriate and should beinserted where necessary. Paragraphdivision numbers should be of the form 0(only for introduction), 1, 1.1, 1.1.1, 2, 2.1,2.1.1, etc.

References should be typed on amanuscript page at the end of the text inorder of appearance. References toperiodicals should include the authors’names, title of article, periodical title,volume, page numbers, year and monthof publication. Book references shouldcontain the names of the authors, title ofbook, edition (if other than first), nameand location of publisher, publication year,and page numbers. References to AESconvention preprints should be replacedwith Journal publication citations if thepreprint has been published.IllustrationsFigure captions should be typed on aseparate sheet following the references.Captions should be concise. All figures

should be labeled with author’s name andfigure number.Photographs should be black and white prints without a halftone screen,preferably 200 mm x 250 mm (8 inch by10 inch).Line drawings (graphs or sketches) can beoriginal drawings on white paper, or high-quality photographic reproductions.The size of illustrations when printed in theJournal is usually 82 mm (3.25 inches)wide, although 170 mm (6.75 inches) widecan be used if required. Letters on originalillustrations (before reduction) must be largeenough so that the smallest letters are atleast 1.5 mm (1/16 inch) high when theillustrations are reduced to one of the abovewidths. If possible, letters on all originalillustrations should be the same size.Units and SymbolsMetric units according to the System ofInternational Units (SI) should be used.For more details, see G. F. Montgomery,“Metric Review,” JAES, Vol. 32, No. 11,pp. 890–893 (1984 Nov.) and J. G.McKnight, “Quantities, Units, LetterSymbols, and Abbreviations,” JAES, Vol.24, No. 1, pp. 40, 42, 44 (1976 Jan./Feb.).Following are some frequently used SIunits and their symbols, some non-SI unitsthat may be used with SI units (), andsome non-SI units that are deprecated ( ).

Unit Name Unit Symbolampere Abit or bits spell outbytes spell outdecibel dBdegree (plane angle) () °farad Fgauss ( ) Gsgram ghenry Hhertz Hzhour () hinch ( ) injoule Jkelvin Kkilohertz kHzkilohm kΩliter () l, Lmegahertz MHzmeter mmicrofarad µFmicrometer µmmicrosecond µsmilliampere mAmillihenry mHmillimeter mmmillivolt mVminute (time) () minminute (plane angle) () ’nanosecond nsoersted ( ) Oeohm Ωpascal Papicofarad pFsecond (time) ssecond (plane angle) () ”siemens Stesla Tvolt Vwatt Wweber Wb

INFORMATION FOR AUTHORS

Conference preview: Vol. 50, No. 4,pp. 290–301 (2002 April)

RU-198005 St. Petersburg, RussiaTelephone/Fax: +7 812 5951730Email: [email protected]

Call for papers: Vol. 49, No. 9,p. 851 (2001 September)

Conference preview: Vol. 50, No. 4,pp. 274–289 (2002 April)

Papers cochair: Lars Gottfried JohansenAalborg UniversityNiels Jernes Vej 14, 4DK-9220 Aalborg ØPhone: +45 9635 9828E-mail: [email protected]

Call for papers: This issue,p. 641 (2002 July/August)

Exhibit information:Thierry BergmansTelephone: +32 2 345 7971Fax: +32 2 345 3419Email: [email protected]

Call for papers: Vol. 50, No. 6,p. 535 (2002 June)

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JOURNAL OF THE AUDIO ENGINEERING SOCIETYAUDIO / ACOUSTICS / APPLICATIONSVolume 50 Number 7/8 2002 July/August

In this issue…

Amplifier OutputStages

Low-Frequency Sound Reproduction

Reconstructing Missing Audio

Standards:Call for Comment

Features…

113th ConventionLos Angeles—Preview

23rd Conference, Copenhagen—Call for Papers

Update: Sections Directory

The Audio Engineering Society recognizes with gratitude the financialsupport given by its sustaining members, which enables the work ofthe Society to be extended. Addresses and brief descriptions of thebusiness activities of the sustaining members appear in the Octoberissue of the Journal.

The Society invites applications for sustaining membership. Informa-tion may be obtained from the Chair, Sustaining Memberships Com-mittee, Audio Engineering Society, 60 East 42nd St., Room 2520,New York, New York 10165-2520, USA, tel: 212-661-8528. Fax: 212-682-0477.

ACO Pacific, Inc.Air Studios Ltd.AKG Acoustics GmbHAKM Semiconductor, Inc.Amber Technology LimitedAMS Neve plcATC Loudspeaker Technology Ltd.Audio LimitedAudiomatica S.r.l.Audio Media/IMAS Publishing Ltd.Audio Precision, Inc.AudioScience, Inc.Audio-Technica U.S., Inc.AudioTrack CorporationAutograph Sound Ltd.B & W Loudspeakers LimitedBMP RecordingBritish Broadcasting CorporationBSS Audio Cadac Electronics PLCCalrec AudioCanford Audio plcCEDAR Audio Ltd.Celestion International LimitedCentre for Signal ProcessingCerwin-Vega, IncorporatedCommunity Professional Loudspeakers, Inc.Cox Audio EngineeringCrystal Audio Products/Cirrus

Logic Inc.D.A.S. Audio, S.A.D.A.T. Ltd.dCS Ltd.Deltron Emcon LimitedDigidesignDigigramDigital Audio Disc CorporationDolby Laboratories, Inc.DRA LaboratoriesDTS, Inc.DYNACORD, EVI Audio GmbHEastern Acoustic Works, Inc.Eminence Speaker LLC

Event Electronics, LLCFerrotec (USA) CorporationFocusrite Audio Engineering Ltd.Fostex America, a division of Foster Electric

U.S.A., Inc.FreeSystems Private LimitedFTG Sandar TeleCast ASGentner Communications Corp.Harman BeckerHHB Communications Ltd.Innova SONInnovative Electronic Designs (IED), Inc.International Federation of the Phonographic

IndustryJBL ProfessionalJensen Transformers Inc.Kawamura Electrical LaboratoryKEF Audio (UK) LimitedKenwood U.S.A. CorporationKlark Teknik Group (UK) PlcKlipsch L.L.C.Laboratories for InformationLectret Precision Pte. Ltd.Leitch Technology CorporationLindos ElectronicsMagnetic Reference Laboratory (MRL) Inc.Martin Audio Ltd.Meridian Audio LimitedMetropolis Studios and MasteringMiddle Atlantic Products Inc.Mosses & MitchellM2 Gauss Corp.Music Plaza Pte. Ltd.National Semiconductor CorporationGeorg Neumann GmbH Neutrik AGNVisionNXT (New Transducers Ltd.)1 LimitedOntario Institute of Audio Recording TechnologyOutline sncPRIMEDIA Business Magazines & Media Inc.Prism Sound

Pro-Bel LimitedPro-Sound NewsRadio Free AsiaRane CorporationRecording ConnectionRocket NetworkRoyal National Institute for the BlindRycote Microphone Windshields Ltd.SADiESanctuary Studios Ltd.Sekaku Electron Ind. Co., Ltd.Sennheiser Electronic CorporationShure Inc.Snell & Wilcox Ltd.Solid State Logic, Ltd.Sony Broadcast & Professional EuropeSound Devices LLCSound On Sound Ltd.Soundcraft Electronics Ltd.Soundtracs plcSowter Audio TransformersSRS Labs, Inc.Stage AccompanySterling Sound, Inc.Studer North America Inc.Studer Professional Audio AGTannoy LimitedTASCAMTHAT CorporationTOA Electronics, Inc.TommexTouchtunes Music Corp.United Entertainment Media, Inc.Uniton AGUniversity of Essex, Dept. of Electronic

Systems EngineeringUniversity of SalfordUniversity of Surrey, Dept. of Sound

RecordingVidiPaxWenger CorporationJ. M. Woodgate and AssociatesYamaha Research and Development

journal aes 2002 jul-ago vol 50, num 7-8

Documents

audio precision

martin audio

audio mediaimas

audio limitedaudiomatica

new york

sustaining membership

sadiesanctuary studios

air studios