The standard reverberation time T60 is defined by a 60 dB sound energy decay.

Evidence

Equation A4.8 gives a relationship between the ratio of sound energy decay and the time it takes, and so can be used to calculate this time. There are an infinite number of possible ratios that could be used. However, the most commonly used ratio is that which corresponds to a decrease in sound energy of 60 dB, or 106. When this ratio is substituted into Equation A4.8 we get an equation for the 60 dB reverberation time, known as T60, which is: where T60  the 60 dB reverberation time (in s) Thus the reverberation time is given by: where T60  the 60 dB reverberation time (in s) Equation A4. — David Howard, Jamie Angus, coustics and Psychoacoustics, 2821

Categorization

• DEFINE: Defines T60 — the canonical reverberation-time parameter — and explains why 60 dB was chosen: it is simply the most common of infinitely many possible decay ratios.