acoustics i: building acoustics - people.ee.ethz.chisistaff/courses/ak1/... · building acoustics...

Building acoustics

introduction

airborne soundinsulation

single walls

double walls

standard soundpressure leveldifference

impact soundinsulation

SIA 181

construction hints

movie Cremer /Frobe

back

Acoustics I:building acoustics

Kurt Heutschi2013-01-25

Building acoustics

introduction

airborne soundinsulation

single walls

double walls

standard soundpressure leveldifference

impact soundinsulation

SIA 181

construction hints

movie Cremer /Frobe

back

introduction

Building acoustics

introduction

airborne soundinsulation

single walls

double walls

standard soundpressure leveldifference

impact soundinsulation

SIA 181

construction hints

movie Cremer /Frobe

back

introduction

I building acoustics → noise abatement in buildings(suppression of noise from neighbors)

I annoying sound is radiated by walls or ceilings

I excitation of these surfaces:I airborne sound sources such as e.g. voices,

loudspeakersI structure borne sound → vibration sources such as

e.g. footsteps

Building acoustics

introduction

airborne soundinsulation

single walls

double walls

standard soundpressure leveldifference

impact soundinsulation

SIA 181

construction hints

movie Cremer /Frobe

back

introduction

I material properties regarding suppression of airbornesound transmission → airborne sound insulation

I material properties regarding suppression ofstructure borne sound transmission → impact soundinsulation

Building acoustics

introduction

airborne soundinsulation

single walls

double walls

standard soundpressure leveldifference

impact soundinsulation

SIA 181

construction hints

movie Cremer /Frobe

back

airborne sound insulation

Building acoustics

introduction

airborne soundinsulation

single walls

double walls

standard soundpressure leveldifference

impact soundinsulation

SIA 181

construction hints

movie Cremer /Frobe

back

airborne sound insulationexperiment:

I airborne sound insulation: capability of a structureto suppress the transmission of sound that wasexcited by airborne sound

Building acoustics

introduction

airborne soundinsulation

single walls

double walls

standard soundpressure leveldifference

impact soundinsulation

SIA 181

construction hints

movie Cremer /Frobe

back

airborne sound insulation

I sound insulation index R (independent of the area!):

R = 10 log

(P1

P2

)[dB]

whereP1: incident sound power on the sender sideP2: sound power that is radiated by the rear side of thestructure

Building acoustics

introduction

airborne soundinsulation

single walls

double walls

standard soundpressure leveldifference

impact soundinsulation

SIA 181

construction hints

movie Cremer /Frobe

back

airborne sound insulation

I measurement of R :

P1 =

p21

ρc

4S

p1: sound pressure in sender roomS : area of the structure under consideration

P2 =

p22

ρc

4A2

p2: sound pressure in the receiving roomA2: total absorption in the receiving room = 0.16V2/T2

Building acoustics

introduction

airborne soundinsulation

single walls

double walls

standard soundpressure leveldifference

impact soundinsulation

SIA 181

construction hints

movie Cremer /Frobe

back

airborne sound insulation

from above follows:

R = 10 logp2

1

p22

+ 10 logS

A2

and finally:

R = L1 − L2 + 10 log

(S

A2

)[dB]

with:L1: average sound pressure level in the sender room (inthird octaves)L2: average sound pressure level in the receiving room (inthird octaves)

Building acoustics

introduction

airborne soundinsulation

single walls

double walls

standard soundpressure leveldifference

impact soundinsulation

SIA 181

construction hints

movie Cremer /Frobe

back

airborne sound insulation

I sound insulation index R is frequency dependent

I weighting of the frequency response with areference curve → single value: rated soundinsulation index Rw

Building acoustics

introduction

airborne soundinsulation

single walls

double walls

standard soundpressure leveldifference

impact soundinsulation

SIA 181

construction hints

movie Cremer /Frobe

back

sound insulation of singlewalls

Building acoustics

introduction

airborne soundinsulation

single walls

double walls

standard soundpressure leveldifference

impact soundinsulation

SIA 181

construction hints

movie Cremer /Frobe

back

sound insulation of single walls

I for plates, R depends on:I area specific mass m′′

I thicknessI density

I modulus of elasticityI frequency

Building acoustics

introduction

airborne soundinsulation

single walls

double walls

standard soundpressure leveldifference

impact soundinsulation

SIA 181

construction hints

movie Cremer /Frobe

back

sound insulation of single wallstypical frequency dependency of R :

region A mass law: R = 20 log(f ·m′′)− 47 [dB]

region B coincidence collapse f(φ):λbending:wave:plate = λprojection:air:borne:sound:wave

region C above coincidence, increase about 25dB/decade

Building acoustics

introduction

airborne soundinsulation

single walls

double walls

standard soundpressure leveldifference

impact soundinsulation

SIA 181

construction hints

movie Cremer /Frobe

back

sound insulation of doublewalls

Building acoustics

introduction

airborne soundinsulation

single walls

double walls

standard soundpressure leveldifference

impact soundinsulation

SIA 181

construction hints

movie Cremer /Frobe

back

sound insulation of double walls

I construction:I wall 1 + spacing (usually air) + wall 2I assumption of piston movement of walls: mass +

spring + mass

I → resonance leads to a collapse of sound insulation

I above resonance massive increase of soundinsulation with frequency

Building acoustics

introduction

airborne soundinsulation

single walls

double walls

standard soundpressure leveldifference

impact soundinsulation

SIA 181

construction hints

movie Cremer /Frobe

back

standard sound pressurelevel difference

Building acoustics

introduction

airborne soundinsulation

single walls

double walls

standard soundpressure leveldifference

impact soundinsulation

SIA 181

construction hints

movie Cremer /Frobe

back

standard sound pressure level difference

I disturbance relative to a noisy neighbor depends onI sound insulation index R of the structural elementsI common area F of the structural elementsI absorption, respectively reverberation of the

receiving room → normalized to 0.5 s

I → Standard sound pressure level difference DnT

Building acoustics

introduction

airborne soundinsulation

single walls

double walls

standard soundpressure leveldifference

impact soundinsulation

SIA 181

construction hints

movie Cremer /Frobe

back

standard sound pressure level difference

it can be found:

DnT = R + 10 log

(V

F

)− 4.9

with:V : room volume of the receiving room [m3]F : common area

I rated sound insulation index Rw → rated standardsound pressure level difference DnT ,w

Building acoustics

introduction

airborne soundinsulation

single walls

double walls

standard soundpressure leveldifference

impact soundinsulation

SIA 181

construction hints

movie Cremer /Frobe

back

impact sound insulation

Building acoustics

introduction

airborne soundinsulation

single walls

double walls

standard soundpressure leveldifference

impact soundinsulation

SIA 181

construction hints

movie Cremer /Frobe

back

impact sound insulation

I excitation by hammers → standardized tappingmachine

I hammers of specified weightI specified falling heightI specified excitation frequency

Building acoustics

introduction

airborne soundinsulation

single walls

double walls

standard soundpressure leveldifference

impact soundinsulation

SIA 181

construction hints

movie Cremer /Frobe

back

impact sound insulation

I measurement of average sound pressure level Li inthird octaves in the receiver room

I calculation of standard impact sound level Ln inthird octaves: total absorption of 10 m2 in thereceiving room is assumed

Ln = Li − 10 log

(10Ti

0.163V

)where:V : volume of the receiving room [m3]Ti : reverberation time in the receiving room in thirdoctaves

I translation into single value Ln,w analogous tosound insulation index by using a reference curve.

Building acoustics

introduction

airborne soundinsulation

single walls

double walls

standard soundpressure leveldifference

impact soundinsulation

SIA 181

construction hints

movie Cremer /Frobe

back

Swiss standard SIA 181

Building acoustics

introduction

airborne soundinsulation

single walls

double walls

standard soundpressure leveldifference

impact soundinsulation

SIA 181

construction hints

movie Cremer /Frobe

back

SIA 181: Noise protection in buildings

I SIA 181: defines building acoustical requirementsaccording to state of the art in building technology

I noise protection defined for two classes:I minimal requirements

I have to be fulfilled alwaysI elevated requirements

I have to be applied for single family houses thatare built together

I may be applied in other situations withagreement by contract

Building acoustics

introduction

airborne soundinsulation

single walls

double walls

standard soundpressure leveldifference

impact soundinsulation

SIA 181

construction hints

movie Cremer /Frobe

back

SIA 181: Noise protection in buildings

I requirements defined as limiting values forI sound pressure level differences for

I exterior airborne soundI interior airborne sound

I impact sound

Building acoustics

introduction

airborne soundinsulation

single walls

double walls

standard soundpressure leveldifference

impact soundinsulation

SIA 181

construction hints

movie Cremer /Frobe

back

SIA 181: Noise protection in buildings

I two dimensional scheme of limiting values:I first dimension: intensity of the sourceI second dimension: degree of sensitivity of the

inhabitants for a certain usage of the room

Building acoustics

introduction

airborne soundinsulation

single walls

double walls

standard soundpressure leveldifference

impact soundinsulation

SIA 181

construction hints

movie Cremer /Frobe

back

construction hints for goodbuilding acoustical

conditions

Building acoustics

introduction

airborne soundinsulation

single walls

double walls

standard soundpressure leveldifference

impact soundinsulation

SIA 181

construction hints

movie Cremer /Frobe

back

construction hints for good building

acoustical conditions

arrangement of rooms:

I suitable arrangement of rooms may help to avoidnoise problems

I good strategy: no rooms with different usage nextto each other (horizontally and vertically)

Building acoustics

introduction

airborne soundinsulation

single walls

double walls

standard soundpressure leveldifference

impact soundinsulation

SIA 181

construction hints

movie Cremer /Frobe

back

construction hints for good building

acoustical conditions

doors and windows:

I typical maximum sound insulation of doors andwindows: 35 to 40 dB

I usually significantly weaker than walls

I for elevated requirements special constructions haveto be used

Building acoustics

introduction

airborne soundinsulation

single walls

double walls

standard soundpressure leveldifference

impact soundinsulation

SIA 181

construction hints

movie Cremer /Frobe

back

construction hints for good building

acoustical conditions

leakage:

I already small openings (cracks) reduce soundinsulation between adjacent rooms drastically

I typical leakage elements: lead-throughs for cables orventilation ducts

Building acoustics

introduction

airborne soundinsulation

single walls

double walls

standard soundpressure leveldifference

impact soundinsulation

SIA 181

construction hints

movie Cremer /Frobe

back

construction hints for good building

acoustical conditions

floating floors:

I bad idea to put walls directly on concrete floor →high structure borne sound transmission

I remedy: floating floors:I put layer of low stiffness on the concrete floorI floating top cover without contact to walls

Building acoustics

introduction

airborne soundinsulation

single walls

double walls

standard soundpressure leveldifference

impact soundinsulation

SIA 181

construction hints

movie Cremer /Frobe

back

movie Cremer / Frobe

Building acoustics

introduction

airborne soundinsulation

single walls

double walls

standard soundpressure leveldifference

impact soundinsulation

SIA 181

construction hints

movie Cremer /Frobe

back

movie Cremer / Frobe

Lehrfilm Cremer Frobe - Teil 1Lehrfilm Cremer Frobe - Teil 2

Building acoustics

introduction

airborne soundinsulation

single walls

double walls

standard soundpressure leveldifference

impact soundinsulation

SIA 181

construction hints

movie Cremer /Frobe

back

eth-acoustics-1