The time taken by the sound to fall from its average intensity to inaudibility is called the reverberation time. It is also defined as time during which the sound intensity falls from its steady state value to its one-millionth value after the source is shut off

$ ∴ I/I_0 = 10^{(-6)}$

SABINES FORMULA.

Sabines derived an expression for the reverberation time of a furnished hall as follows. The decay intensity is given by,

$ I =I_0 e^{(-KT)}$ $ ∴ I/I_0 = 10^{(-6)}$ $ Hence, T= 1/K log_e⁡(I_0/I= 2.303/K log_10⁡(I_0/I = 2.303/k×6)) $

Hence reverberation time is given by T = 0.161 ×V/A …………………………..(1)

Hence equation (1) is called as sabines formula.