1. Reverberation time

2. Reverberation time (1) Lets consider a room containing an active sound source, and lets abruptly interrupt the emission of sound energy. We define as reverberation time RT (s) of an environment, the time necessary for the sound energy density to decrease to a millionth (60 dB) of the value it had before the source was switched off. Sound energy density Steady-state sound energy density Relative sound pressure level (dB)

3. Reverberation time (2)

4. Lp (dB) Time (s) 45 dB ISO 3382 - 2011 -5 dB -25 dB T 20 T20-5 / -25 (*3) T30-5 / -35 (*2) T10 (unused)-5 / -15 (*6) EDT (early decay time)0 / -10

5. Sabines Formula (3) If the environment is perfectly reverberant the value of the reverberation time is the same in all points and is (s) where V is the volume of the environment. This relation is known as Sabines formula. By measuring the reverberation time, it is possible to determine: A= S equivalent area of acoustic absorption

6. Sabines Formula Substituting in the critical distance formula: