1. acoustic dimensioning - GLAUNACH Vent Silencers

Example Calculation:
IMPORTANT REMARK
The distance from the silencer axis to the silencer shell
must also be considered in the noise calculation
THE SILENCER HANDBOOK
Part IV | page 4 of 14
The sound pressure level Lp5m measured 5 m from the silencer exit is 90 dB.
a) Calculate the Sound Power Level LW 1)
b) Calculate the expected sound pressure level Lp20m at a distance of 20 m
from the outlet
r
1) assuming a point source
0.5m 5m
© GLAUNACH GMBH Edition 2010
a)
∆Lr = 10×log(2×π×(0.5+5)²)
∆Lr = 22,8 dB
L W = L p5m + ∆L r = 90 + 22.8
LW = 112.8 dB
b)
L p20m = L W – 10×log(2×π×r²) =
112,8 – 10×log(2×π×(0.5+20)²)
L p20m = 78.6 dB
or, directly
L p20m = L p5m – 20×log×(r 2 /r 1 ) =
90 – 20×log((0.5+20)/(0.5+5))
L p20m = 78.6 dB