1.
Acoustics 3 – Room Acoustics
Room Acoustics – Reverberation Time
Time (in seconds) required for sound in a space to decay (once it is abruptly stopped)
by some fixed decibel value is reverberation time. Sabine’s formula measures the
reverberation time as time taken by sound to decay by 60dB.
The empirical relationship between the volume of the space, the amount of absorptive
material within the space and the reverberation time is termed as Sabine’s Formula.
RT=0.161V
A
Where, RT = Reverberation time
V = volume of space in m3
A=Total Absorption of space in m2-sabins (Absorption Coefficient)
The constant 0.161 is an inverse log factor of speed of sound, and has a unit of seconds
per meter.

2.
Acoustics 3 – Room Acoustics
Room Acoustics – Reverberation Time
Numerical 3:
Calculate the RT60 of a classroom with length 10m, width 5m and height 4m. Wall are
covered with a material having α1=0.35, ceiling with material having α2=0.60 and floor
with material having α3=0.15. (consider the wall openings covered with same material
as wall and all opening are perfectly closed as the time of calculation)
RT=0.161V
A
A room constant = α1s1 + α2s2 + α3s3+….+ αnsn