alexis perepelycia : 'libertad(es) controlada(s)

7/29/2019 Alexis Perepelycia : 'Libertad(Es) Controlada(s)'

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Libertad(es) Controlada(s)

([un]Controlled Freedom[s])

Interactive Music for Computer, Dysklavier and Performer, implementingSensor Technology.

Alexis Perepelycia

Student N 10848045

Sonic Arts Research Centre

Queens University Belfast


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Abstract

The piece Libertad(es) Controlada(s) ([un]Controlled Freedom[s]) is an algorithmicallygenerated piece for Computer, the Yamaha Dysklavier Piano and a Performer.Unlikely most musical pieces employing sensor technologies as an interface to controlthe computer, this project proposes the implementation of sensor technology not as amean to control a virtual or synthetic instrument nor to control computer processes asan end itself. Instead, it proposes as a way of interfacing and touch less playing anacoustic instrument. The Performer wears a pair of gloves with built-in sensors. Thesensors track the gestures of the Performer and data is sent to a computer. Thecomputer, then, algorithmically generates a brunch of data, which includes not justmusical notes, but musical ideas with proper dynamics, phrases, accents, articulations,etc. This data is sent to the Piano trough a simple MIDI connection.Sound processes are applied both to the direct signal of the Piano and to the sampledsound. Reverberation and Pitch Transposition are the main processes involved. Theyare used to extend the music possibilities of the instrument either to extend theduration of notes or by transposing them onto an unusual register for the Piano.

The piece enhances the Interaction (action and reaction) between the three elementsthat conform it: the logical one (computer), the acoustical one (piano) and the living one(human, performer), whom is actually the one deciding what is the piece going to be,musically; by interplaying gesturally either with piano, the computer or both.

Introduction

With the increment of Live Electronic Music and Electro-acoustic Musicincluding acoustic instruments in live performances, the correlation betweengesture and sonic representation became vague. The paradigm of achievingalmost any imaginable sound by hitting a key of a Laptop keyboard, clicking a

mouse button or by turning knobs and sliders of a MIDI controller seems tohave left expressiveness aside form the performers. They seem to spend mosttime trying to remember which actions they have assigned to their computersand what does each button, knob and fader from their MIDI controller doesrather than focusing on the actual performance and music.Therefore, integration between the instrument and the performer became anissue that needs to be solved if we want the computer and electronic devices toenhance gestures being made by performers. A proper translation of thePerformers gestures into adequate musical representations would enrich theactual performance by providing the Performer with reliable musical feedbackfrom its arms and hands motion. The implementation of Sensor Technology

would give the Performer an answer to the paradigm, by making use of aflexible system that provides them with freedom enough to manipulate theneeded amount of parameters to get the best musical result. Hence, touch lessaction will enhance musical gestures by not being linked to non-musical devicessuch as faders or knobs-based MIDI controllers, which belong more to studioenvironments than to the performance stage.The piece Libertad(es) Controlada(s) ([un]Controlled Freedom[s]), proposesthe implementation of Sensor Technology into a pair of gloves that will suit theperformers hands to provide the computer with information related to thegestures and movements being made by the performer throughout the piece.Furthermore, it intends to establish a link between the Performer and an

acoustic instrument to take advantage of the properties of acoustic sound andintegrating them into the music.


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Development (I)

Overview

1.1) Key points to achieve/combine to get the desired result:

- Gesture- Action/Reaction- Feedback- Direct/non-direct related Gesture and Sound- Interactivity- Interdependence- Touch less produced acoustic sounds- Blend of processed sounds

1.2) The Importance of the Acoustic Instrument

Once the key points were set I had to determine which instrument to use. It hadto be an acoustic instrument allowing me to achieve my goals in terms ofinteractivity and yet provide me with an acoustically rich sound covering theharmonic spectrum as much as possible. Therefore, the best possibility was toimplement the Yamaha Dysklavier, since a crucial point was the possibility tosend data from the computer it. Another possibility would have been to attach aspecifically developed actuator (e.g. servos) to different types of instruments

like an acoustic guitar or bowed instrument. But the complexity of such a taskwould have taken me most part of the project and that wasnt the aim of thepiece.

Development (II)

Music

2.1) Concept

Since my intention was to make a music piece for a performer (not necessarilyan instrumentalist) linked with sensors to an acoustic instrument I had to focusin the interaction between the two elements. I had to decide then, the amountthe interaction and the way I was going to treat action/reaction on each side ofthe system: performer-instrument. I have decided then to write an algorithmicand rely partially on the computer, since each one is an element and note awhole of the music. That resulted in a piece where the performer could make a

certain influence on the behaviours of the instrument by sending different orders(signals) but not being able to control everything in a determined way but rather


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in an indeterminate way. To make cover this are I had programmed agenerative engine which give a brunch of notes when an order is received. Inthis situation the performer might give the computer a direction with certainintention but he/she will never be able to determine precisely the ending result,as the computer will finally react to the action produced by the performer and

produce the sonic material.To avoid the computer to take unwanted paths and in order to get interestingmusical results I decided to provide the performer with control over certainparameters such as:

- Harmonic structure (modal/atonal).- Timbre/Colour (bright/dark).- Density (tight/wide spectrum).- Sound distance (far/close).- Sound source (acoustic instrument/computer).- Combinations of the mentioned above.

Harmonic Structure: I had decided not to use tonality since I dont feel it wouldbring me the tonal characteristics I wanted for this piece. Therefore, I hadapproached the Harmonic Structure in a way that allowed me to have two verydistinctive and very contrasting sonic materials. In order to achieve this I havemade use of Modality and Atonality. Each one has unique characteristics thatprovided me with great tools to achieve sonic contrasts.

Timbre/Colour: I have made use of different articulations to achieve differentsound properties and get different effects in specific sections on the music.

Density: I have included, when programming the patches, the option for theperformer either to cover the whole harmonic spectrum of the piano whileplaying a phrase or to focus on a certain section of the keyboard.

Sound distance: By implementing reverberation, as well, the feel of closenessand farness is achievable.Sound source: Despite the Piano being the only instrument involved ingenerating sound by its own, I had the idea of interacting between the originalsound and the hacked(sampled) one, by extending the piano possibilities.

2.2) Modes

General:

- None of the Modes have the same amount of notes.- None of the Modes have the same Root note.- Every Mode has different tonal (sonic) characteristics.- Some of the Modes are more artificial than others, perhaps because of

the use of Chromatic intervals (Mode IV), resulting in denser harmonies.


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- Some Modes have more conventional structures, close to Tonalstructures (Mode III) resulting in almost diatonic and less denserharmonies.

Description of each Mode:

Mode I Mode II Mode III Mode IVRoot E C D AAmount ofNotes

6 9 8 7

Notes E F G Bb C# - D#

C D Eb - E F F# - G A Bb

D E F G A Bb - C C#

A D# - E F F# - G G#

Characteristics The Notes 1, 3,4 y 5 form a

Diminished 7thchord.

The other twonotes (3 y 6)are bothsensible of theroot, dependingon the directionthe mode isplayed.

Notes 1, 2, 7and 9 form C7 =

C (b3, b7)

Note 2 is the 9thof the chordwhile note 8 isthe 13th.

This Modecould beungrouped intoa minor 3rd (C,D, Eb:

diatonicallyfilled) + a Major3rd (Eb, E, F,F#, G:chromaticallyfilled) + a 4th(G, A, Bb, C:diatonicallyfilled).

Notes 1, 3, 5and 7 (odds)

form D minorwith flat 7th = D(b3/b7).

The maincharacteristic ofthis mode isthat it could beunderstood asan Aeolianmodetransposed to

D, but with theMajor 7th added,resulting in ascale with twosevenths, minorand major.

The maincharacteristic of

this mode isthat its formedby twoaugmentedfourths(tritones).

The first ofthem is aninterval whilethe second ischromatically

filled.


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Explanatory graphic on the inter-relations between the four Modes:

- Continuous lines show common notes between all the modes.- Dotted lines show the structure of the three common notes inside each

mode.- Dashed lines show common notes between two or three modes.

2.3) Formal Criteria

2.3.1) General

Formally the piece has five sections clearly marked by a silence between each.Sections I, II and V have two smaller sections inside whereas sections III and IVhave no sections inside. Sections II and I are built on the principle of questionand answer. The question is being asked (played) by the piano, while theanswer, is given (sounded) by the computer by playing back the sound(question) and processing it. Section III is a solo section. On it, the piano playsa Modal solo throughout the whole section. Since it is supposed to be played ina lonelyway, the computer adds slightly variations of reverberation to play withthe idea of sound distance. In Section IV and in Section V piano and computerplay simultaneously. In Section IV the computer creates a thick density byadding excessive reverberation and in Section V the computer interferes thedialogue of the piano by playing back samples of the previous section andtransposing them at quartertones.Although the timing is relative, duration of approximately 20 minutes is

recommended for performances. The scored timing is 21 minutes.


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If a different duration is chosen for performance, the sections should maintainits proportion between them, as follows:

- Section I ~ 1/10- Section II ~ 1/5 (~2* Section I)

-Section III ~ (~ 2* (Section B)-1)

- Section IV ~ 1/10 (~ Section I)- Section V ~ 1/5 (~ Section 2)

2.3.2) Sections

a) Sections Ia and Ib (Intro)

The first section of the piece is made of two different sub-sections. Bothconstitute the opening for the piece. Section Ib starts with a series of clusters inthe highest register of the Piano at a forte (loud) dynamic and starts a chromaticglissando downwards, as it speeds up gradually. The idea of the Intro is to getas much of the resonance of the instrument as possible by using the pedal to letall the strings ring and to make the other strings sympathetically vibrate. Inaddition to this, to enhance even more this effect, the computer addsreverberation once the performer reaches the lower register of the piano andwhile repeating at fast tempo a few clusters. At this point the signal is feed intoa sampler. After the sound is sampled a transition to Section Ib, begins byplaying back the sampled sounds from the very end of the previous section.

Section Ib discards the idea of resonance but preserves a certain moodof itsince it is build from a sample of Section Ia plus transposes it in a non usualway for the piano. It is played back forward and backwards in a loop mode andtransposed first surrounding the tonal centre of the sample and later extendingthe spectrum of the original sample, till the end of the section when thetransposition reaches around an octave below the original tone.Section I (a and b) ends with a silence to separate it from Section II.

b) Sections IIa and IIb

In the beginning of Section IIa the following conditions for the Piano, are set:

- Play as fast as possible- Play aspiano (quiet) as possible- Play with mechanical articulation (short notes)- Start in the middle register and gradually spread the note within the

whole register- Crescendo poco a poco (increase dynamics gradually)- Let the piano resonate again, by pressing the pedal down


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The aim of those directions is to try to achieve an effect similar to GranularSynthesis by playing short notes really fast and at distant intervals. This processwould not be achievable, normally, by a piano player, so I decided to include itin the piece to show the possibilities of the system. This section, generates agreat contrast in terms of chronometric density, with the previous section and

provides the sampler with a great steady signal to develop the second half (b) o fSection II. During the last half of Section II the idea is to produce a blurtransformation of the sampled sound from the first half. Because of that, a greatamount of reverberation is applied while sampling the end of the first half of thewhole section. While the blurred effect takes shape the Piano starts shading tillit disappears completely leaving the blurred samples playing in loop mode tillthe end of Section IIb. The section finishes with a fade out followed by adramatic silence of a few seconds to give air to the following section.

c) Section III (solo)

In a lonely way. That is the way this section is intended to be played. It is then,an airy and open section where there is a lot of time and space for each note.This is the core section of the piece, lasting about half of the total duration of thepiece. It is entirely built on the Artificial Modes (described in chapter 2.2 of thispaper) in order to generate not just a contrast but also a balance or maybe anunbalance, since till this section the criteria of tonality or modality is avoided(replaced) by the idea of atonality, so the listener is not expecting any specificharmonic structure. Intentionally it happens in the core section, in the solosection, where the piano takes all the attention.As this section is the solo section of the piece, on it, the computer enhances the

musical ideas developed by the Piano. Working on favour to the pure acousticsound by adding small amounts of reverberation just to get the feeling ofdistance (farness/closeness) to mask the transitions between Modes, whichsuppose to be almost unnoticeable.

d) Section IV

This section works as an interference to the end of the solo section. It producesa sudden shift in the mood built during the solo, contrasting completely with thelonely feeling of Section III. It is based on the same harmonic material thanSection I but this section has a linear approach. That is, instead of using verticalstructures (clusters, chords) I have used arpeggios (notes played sequentiallylike a broken chord) to achieve a linear feel. The section has the followingconditions set:

- Start with slightly fasts arpeggios.- Start in the high register and then randomly glissandi to the low register.- Increase the tempo (accelerate) gradually.- Increase dynamics gradually from mezzo forte to fortissimo within the

whole section.


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- Gradually spread arpeggio time (time between notes) [in order to achievethis you should turn the Cluster Transformation Time button on, beforethe beginning of the section].

- Gradually thicken the texture by adding reverberation.

The arpeggios could be spread over the whole range of the Piano, but this isnot essential, since it is left to the performers will.The section ends with a moderate silence which doubles as a separatorbetween this section and the following.

e) Section V (coda)

The final section of the piece is intended as a coda. And thus, it combineselements used in the other four sections to create a new structure. The sectionstarts with an atonal single line being played at a moderate tempo and it quickly

introduces changes on register, tempo (accelerates) and loudness (increases).After a moment, samples from the previous section are sounded andtransposed within a range of an octave as the loudness increases to the highestdegree. Next to the little atonal sub-section, while the sampled sounds reach itsloudest peak, cutting through the mass of sound a modal sub-section begins. Itimplements Mode 3 to evoke a pseudo-melody that will lead to a final atonalsection, which will sinks into the sounds from the sampler, by this stage beingtransposed at quartertones. The last breath of sounds will gradually fades intothe silence, finishing the music in loneliness.

Development (III)

Building the System

3.1) The Glove

Since I wanted to enhance the interaction between Performer and Instrument byusing a type of Interface that would allow this I have decided to implement apair of gloves with sensors built in to convert gesture (motion) from thePerformer into data to control the Computer and thus the Piano.To achieve as much control over the computer as possible I had to track asmuch of the motion as possible. In order to do that I had to include severaltypes of sensors to track different types of movement and different actions thePerformer might do to get different sonic results. The original design per gloveincluded: 4 flexometers, 4 micro switches, 1 dual axis inclination sensor and 1infrared sensor. However, due to budget circumstances the final version has 1dual-axis inclinometer and 4 switches per hand. Cables were routed to an RJ45(UTP) connector and linked to a Basic Stamp Board next to the Computer, with

a UTP cable (w/ 8 cables inside) to avoid loose cables to interfere with the


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Performers movements.

3.2) The Sensors

After receiving the Sensors available for this project I started to experiment withthem to have an approximate scope of their behaviour and to check if theywould do the tasks I expected them to do.

a) Dual-axis Inclinometers

The first type of sensor I have tried was the Memsic 2125, Dual-axis ThermalAccelerometer. This type of sensor measures static (gravity) acceleration anddynamic (vibration) acceleration over two axis, X and Y. Because of itscapabilities it could be used to measure not just acceleration but also tilt

A RJ45 (UTP) ConnectorB Ground (for all Switches)C Switch 1 (+5v)D Switch 2 (+5v)E Switch 3 (+5v)F Switch 4 (+5v)G Dual-axis Inclinometer


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(inclination) and rotation. Knowing the sensor capabilities I could haveprogrammed two or three different tasks for this type of sensor but instead Idecided to have a relatively simple task in order to have to do, when performing,a fair simple action to get a direct result. As a result I set them to work as dual-axis Inclinometers in order to have the possibility of getting two values (X,Y

position) to control two different parameters.

Memsic 2125

b) Switches

In order to route the incoming signal from the Inclinometers to different

parameters inside the Computer I have implemented four switches, one perfinger but in the thumb, which is in fact the ground (vss) for the other fourfingers, which have a positive pole (vdd)[+5v.] each. Buy touching the tip (whereall the switches are placed) of the thumb with the tip of any other finger, thePerformer closes a circuit, choosing which parameter the data coming from theInclinometer will affect and thus, selecting a parameter to perform with.


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3.2.1) Tested Sensors (not included in the glove)

Despite in the final version of the gloves I have implemented one inclinometerand four switches; during the construction process I have tried several types ofsensors. Next I will mention the most representatives:

a) Flexiforce

On the early stage of development of the gloves I have tried a Force Resistorcalled Flexiforce. This sensor is basically a plastic strip of about 6 inches witha small circle with three pin connections in one end and a small-circled surfacein the other. This circled surface is the area that actually works as a sensor.When you apply a certain pressure in that area, it will send a message to theBasic Stamp Board, which will indicate two values: force applied and time spentapplying it. Those values are used then to fill a capacitor(buffer) and when the

pressure is release the capacitor starts unloading its data.The main problem experienced with this type of sensor was the unreliability ofnot knowing how much pressure is being applied and how long has been sinceone started to apply that pressure. Plus, as it was a plastic strip it was reallycomplicated to attach them properly to the gloves without interfering with thePerformers movements, which might have caused a really awkward feelingwhen performing.Because of those reasons I have decided not to use them in the final version ofthe gloves.

Flexiforce

b) Polaroid Ultrasonic Sonar Transducer

Together with the Flexiforce I have tried a Sonar sensor. I had the idea ofimplementing it to measure distance (proximity) between both hands in order toassign the reverberation amount to that gesture. Although, the type of sensor Icould get was a little bit noisy and when very quiet dynamic levels were neededin the music, one could easily hear the sonars noise. In addition to that, the

main piece of the circuit (the sonar it self) was a little bit too big to fit the gloveand still have a comfortable feel while performing.


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Polaroid Ultrasonic Sonar Transducer

3.2.1) Combining the Sensors

The final version of the gloves I have made to perform the piece included, asshowed previously, a dual axis inclinometer and four switches per hand,providing the performer with to degrees of freedom (X and Y) times four (oneper finger), that is:

- X1, Y1- X2, Y2- X3, Y3- X4, Y4

However, this amount of signal routing was not enough to control all theparameters I needed to control to perform the piece, in order to solve thisproblem I have implemented a foot pedal (keyboard sustain like) to double theamount of routing made to the incoming signal from the Inclinometers. The finalamount of signals would be described as follows:

- X1, Y1 (A)- X1, Y1 (B)- X2, Y2 (A)- X2, Y2 (B)- X3, Y3 (A)- X3, Y3 (B)-

X4, Y4 (A)- X4, Y4 (B)

(A) = Pedal Off(B) = Pedal On


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3.3) The Basic Stamp Board and Basic Programming

In order to get all the sensors working and feeding data into the computer aBasic Stamp Board (BSB) was implemented. In essence a BSB is a device thatallows you to build circuits on it by attaching the needed components (for e.g.

resistors, capacitors, switches, sensors, etc.). However, its main feature is thatit has a built in microcontroller (a type of EEPROM memory) that allows the userto store a small piece of code programmed in Basic language. This is reallyuseful when dealing with sensor technology since one can easily programdifferent tasks to be performed by the received signal coming from the sensors.For instance, one could assign a variable (resizable number) to a certain pin (aninput or output connection terminal) and when the signal goes through it will bedetected by the programmed code and a predetermined action will be done.

Final Basic Stamp Code:

'{$STAMP BS2sx}'{$PBASIC 2.5}' 2 Tilt (2125) Sensors + 8 Switches

top:

' accelerometers variables

x VAR Wordy VAR Word

x1 VAR Wordy1 VAR Word

' switch variables

a VAR Byteb VAR Bytec VAR Byted VAR Bytee VAR Bytef VAR Byteg VAR Byteh VAR Byte

'Loop Section

DO

' accelerometer loop

PULSIN 14, 1, xPULSIN 15, 1, yPULSIN 12, 1, x1PULSIN 13, 1, y1

'switch loop

IF IN1 = 1 THEN a = 0 ELSE a = 1IF IN2 = 1 THEN b = 0 ELSE b = 1IF IN3 = 1 THEN c = 0 ELSE c = 1IF IN4 = 1 THEN d = 0 ELSE d = 1IF IN5 = 1 THEN e = 0 ELSE e = 1IF IN6 = 1 THEN f = 0 ELSE f = 1

IF IN7 = 1 THEN g = 0 ELSE g = 1IF IN8 = 1 THEN h = 0 ELSE h = 1


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'Debugging Section

DEBUG "A ",DEC a, CRDEBUG "B ",DEC b, CRDEBUG "C ",DEC c, CRDEBUG "D ",DEC d, CRDEBUG "E ",DEC e, CRDEBUG "F ",DEC f, CR

DEBUG "G ",DEC g, CRDEBUG "H ",DEC h, CRDEBUG "I ", DEC x,CRDEBUG "J ", DEC y,CRDEBUG "K ", DEC x1,CRDEBUG "L ", DEC y1,CR

PAUSE 1

LOOP

4) Max/MSP Programming

Once I had tested the viability of implementing the Dysklavier and the BasicStamp Board I had to find a piece of software that would allow me to implementthe converted signal coming from the Board and use it to trigger the algorithmsto generate the music and once it would be done, route it to the Piano. Since Ihad used Max/MSP in previous projects I knew this program would allow meperform the tasks I needed.

4.1) Link with Basic Stamp

The first step was to establish the link between the Basic Stamp Board andMax. Since the Board has USB connection I have used an object that detectssignals coming into the Input Ports of the computer. I had the signals from allthe sensors together coming to the same port so I separated them and thenrouted to different sections of the patch.

4.1.1) Filtering and Numbers Conversions

Data coming from the Basic Stamp Board was treated in different ways to getthe desired result, depending on the parameters to be controlled.Hexadecimal to Decimal conversion was applied to route different signalsproperly. As well, several types of filtering of the stream were applied in orderbe able to control the musical parameters with a smooth signal.


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4.2) Programming the Musical Tools

Once the sensor part worked Ok, I could focus totally on the musical side toachieve what I needed, in order to be able to perform the piece. The finalversion of the piano patch for Libertad(es) Controlada(s) has four main

elements: a Cluster Generator, a Single Note, a Two Notes Generatorand aModes. In addition to this, the patch has a signal processing (MSP) part thatincludes: a sampler with controls for sampling time, playback (with choice formirror loop back and forth), half tones transposition (ranging from an octaveabove to an octave below) and quarter tones transposition with the same twooctaves range. Moreover, there is a section of the patch that includesreverberation and it is possible to control the amount of reverberation and theloudness of the reverberated signal.

Final Patch (screenshot):


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4.2.1) Piano Elements

a) Single Notes Generator

In some sections of the piece I make use of atonalism. Because of this I havecreated an engine that automatically generates notes with no hierarchy at all,according to same directions the Performer would give: Pitch Range, RelativeTonal Centre, Dynamics and Tempo.

b) Two Lines Generator

In order to be able to create different densities when using atonality I have builta two lines atonal player, to create some sort of inter-layering between notes,

without actually playing a chord an arpeggio or a cluster. Different dynamicscould be applied to each line to enhance even more this principle. The followingparameters were set for the performer to control: Phrase Length, RelativeTempo, Automatic Tempo (button on/off), Sustain and Dynamics for each ofthe two players.

c) Modes Player

The core section of the piece is based on modal structures. It actually combinesfour different modes (explained on chapter 2.2 of this paper) throughout SectionIII, which is actually the solo section of the piece. To control the different modes

I have implemented a modal player, which controls and combines the fourmodes. On it, the performer controls the following parameters: Mode Selection(I, II, III, IV), Relative Dynamics, Relative Tempo, Sustain and Phrase Length.

d) Clusters Generator

It is used in the opening section and it has the following parameters to control:Tempo, Root note, Length and Articulation.The final part of the patch is a Cluster Generator, which creates six notesclusters, covering a perfect fourth.For instance, if the root note for the Cluster is set to C3, the result will be asfollows:

In addition to the parameters listed above, there is a button set to turn on andoff the cluster Transformation Time. This parameter is used in Section IV toconvert clusters into chromatic arpeggios. The transformation time for arpeggiosworks by delaying the attack of each of the six notes of the cluster with differenttimes. It has a clock that counts the elapsed time and each note has a differentmultiplication factor to get a spread arpeggio that gradually spreads more andmore on time.


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d.1) Delays for transforming Clusters into Arpeggios

Notes to be delayed = 6 (N1, N2,N6)Delay Time = z (ms.)Note 1 will be delayed with delay time z1 (N1 => z1), and so on till N6 => z6.

z1 = z + (z/10)z2 = z + (z/9)*2z3 = z + (z/8)*2.1z4 = z + (z/7)*2.1z5 = z + (z/6)*2.3z6 = z + (z/5)*2.4

This will result in every note, including the root note, being delayed. Every note

except the root will be delayed with a proportional coefficient, being closer toeach other (time wise) and slightly distant from the root, resulting in an unevenarpeggio with a rhythmic rest in the root note. For instance:

For z = 1000 ms.

Z1 = 1100 ms.Z2 = 1222 ms.Z3 = 1262 ms.Z4 = 1312 ms.Z5 = 1318 ms.

Z6 = 1480 ms.

4.2.1) Computer Elements

a) Sampler

The main element of the patch, not intended to control the piano is a sampler. Itis used to record small samples of the Piano while it is playing and then applyfew sound processes like:

- Loop playback- Reverse playback- Mirror playback (back and forth)- Half tones Transposition (within an octave above and an octave below)- Quarter tones Transposition (within the same spectrum the previous)

As sometimes the sound is too quiet, as soon as the sampler stops recordingthe signal is automatically normalized to get a constant sound.


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b) Reverb

The second element in this section is a Reverb based on Christopher KeyesReverb of his Real-Time Granular Cloud Maker.The Reverb has controls for Signal Level and Wet/Dry level. An interesting

feature is an adaptive filter that detects the notes being generated by thecomputer and selects the root frequency of that note in order to avoid feedbackwhen fully wet reverberation is applied to the Piano signal.

Practical Implementation (I)

5) Performing

5.1) The setup for performing the piece should include the following:

- Yamaha Dysklavier Piano or similar.- A computer running Max/MSP version 4.3 or above, with enough CPU

power and ram memory to run both the algorithmic part and the soundprocessing smoothly.

- Two cardioids microphones (or any two directional microphones).- An audio interface with to preamps to connect the microphones to

sample the Piano.- A MIDI interface to connect the computer to the Piano.- A two on/off buttons foot switch or pedal switch.- A Basic Stamp Board (BS2sx or above) and a Basic Stamp Editor

running Basic Stamp 2.5 (to load the code to the microcontroller).- A pair of speakers with its proper amplifier.- The proper gloves to perform it.

5.2) Directions

A few considerations should be taken in performance situations.

- The performer should face the audience in order the let them perceivethe gestures involved in the sound production.

- The computer and the Piano should not interfere between the audienceand the Performer. Though, visual contact with the computer monitor isrecommended.

- The speakers should be on the same line than the Piano, vertically andhorizontally to enhance smooth transitions between reverberated andpure sound. Although the relative position of microphones and speakersshould be considered in order to avoid feedback.

- Long enough cables to link the gloves to the Basic Stamp Board shouldbe implemented in order to provide the Performer with as much freedomof motion as possible.

-All cables connecting interfaces (Audio, MIDI) and microphones orspeakers should be cleared from the Performers area.


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5.3) The Performance space:

A Computer DeskB PianoC Speakers position (in case of using two)e1 and e2 Microphone position when Piano lib half closedf1 and f2 Microphones position when Piano lib removed.


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Conclusions and Future Work

The key point of this project was to create a system, which allows the Performerto interact gesturaly with an Instrument. And that was achieved in the systemdeveloped for the piece Libertad(es) Controlada(s).My experience with the system suggest that sensor technology would be a verypowerful tool to control an acoustic instrument remotely, by translating theperformers gestures into musical information through a computer.In the piece Libertad(es) Controlda(s) the Performer is provided with a reliablewearable interface which allow him/her to contact less interact with the Pianoenhancing the principle of gestural integration between Performer andInstrument.However, the system could be greatly empowered by increasing the amount of

sensors implemented in the actual version. This would give increase theamount of accuracy of the system by tracking in a more adequate way everygesture and movement of the Performer. For instance, with the actualInclinometer the system perceives two degrees of freedom, translated into four.That is, axis X and Y, from 0 to positive and from 0 to negative. But with aninfrared distance measurement sensor a third axis (Z) might be included to giveeven more accuracy to the system.Interesting physical parameters to measure and include in further improvementsto the actual system would be motion and pressure of fingers, distance betweenhands.Another useful improvement would be the implementation of Wireless (Wi-Fi

/Bluetooth) protocol to link the gloves to the Basic Stamp Board in order to setthe Performer free from any cable that might disturb the performance.Finally, despite the piece and the system are intended for a single player, afuture system would include the possibility of multi-players enhancing theinteractivity even more and taking advantage not only of the human-computerinteraction but also of the human-human interaction as in purely instrumentalsituations.

Acknowledgements

I would like to express my gratitude to Dr. Ricardo Climent for his support,enthusiasm and wise guidance throughout the whole project. Without his advicethis project would havent been possible.Thanks Timothy Place for his help on the Tap Tools for the PC version, toJason Dixon for his help with soldering and circuitry stuff.Special thanks to Chris Corrigan for all the technical assistance and for alwaysbeing therewhen needed.Lastly, Id like to dedicate this work to my family and Cecilia Gonzalez for theirunconditional support, always and everywhere.To all of them my gratitude.


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References/bibliography

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07/2005]- SONAMI, Laetitia, 2000 www.sonami.net [retrieved date: 06/2005 ~

07/2005]

alexis perepelycia : 'libertad(es) controlada(s)

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