14: Acoustics of Buildings and Acoustic Quieting

Example number 1, Page number 14.18

In [4]:
#importing modules
import math
from __future__ import division

#Variable declaration
V=2265;      #volume(m**3)
a=92.9;      #absorption(m**2)

#Calculation
T=0.16*V/a;    #reverbration time(s)
T2=T/2;        #reverbration time when audience fill the hall(s)

#Result
print "reverbration time is",round(T,1),"s"
print "reverbration time when audience fill the hall is",round(T2,2),"s"
print "reverbration time is reduced to one-half"

reverbration time is 3.9 s
reverbration time when audience fill the hall is 1.95 s
reverbration time is reduced to one-half

Example number 2, Page number 14.18

In [7]:
#importing modules
import math
from __future__ import division

#Variable declaration
V=12*30*6;    #volume(m**3)
A1=450;       #area of plastered wall(m**2)
a1=0.03;      #coefficient of absorption(m**2)
A2=360;       #area of wooden floor(m**2)
a2=0.06;      #coefficient of absorption(m**2)
A3=24;        #area of glass(m**2)
a3=0.25;      #coefficient of absorption(m**2)
A4=600;       #area of seats(m**2)
a4=0.3;       #coefficient of absorption(m**2)
A5=500;       #area of hall with audience(m**2)
a5=0.43;      #coefficient of absorption(m**2)

#Calculation
A=(A1*a1)+(A2*a2)+(A3*a3)+(A4*a4)+(A5*a5);    #total absorption(m**2)
Ae=A-(A5*a5);                                 #absorption when hall is empty(m**2) 
T=0.16*V/A;   #reverbration time(second)
Te=0.16*V/Ae; #reverbration time when hall is empty(second)

#Result
print "reverbration time is",round(T,1),"second"
print "reverbration time when hall is empty is",round(Te,1),"second"

reverbration time is 0.8 second
reverbration time when hall is empty is 1.6 second

Example number 3, Page number 14.19

In [11]:
#importing modules
import math
from __future__ import division

#Variable declaration
V=7500;    #volume(m**3)
T=1.2;     #reverbration time(second)

#Calculation
A=0.16*V/T;     #total absorption(OWU)

#Result
print "total absorption is",int(A),"m**2 or OWU"

total absorption is 1000 m**2 or OWU

Example number 4, Page number 14.19

In [29]:
#importing modules
import math
from __future__ import division

#Variable declaration
V=12*10**4;      #volume(m**3)
a=13200;         #absorption(m**2)

#Calculation
T1=0.16*V/a;    #reverbration time(s)
T2=T1/2;         #reverbration time when audience fill the hall(s)
T=T1-T2;        #change in reverbration time(second)

#Result
print "change in reverbration time is",round(T,3),"second"

change in reverbration time is 0.727 second