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