Sound decay rate DR = 60 dB / RT60 in dB per second (dB/s)
|Decay rate is:
1. At a given frequency, the rate at which the sound level in a room decreases after a source stops emitting sound; expressed in decibels per second (dB/s).
2. Of sound waves in an enclosed space, the rate at which the sound pressure level of reverberation decreases; usually expressed in decibels per second.
In a control room or a living room we cannot speak any more of the audible
"reverberation response" or "reverb time". There is really no reverberation to hear.
In particular for short reverberation times frequently the "sound decay rate" or "rate of spatial decay" in dB/s is used. This means with which level in dBs per second the sound signal in the room decays after switching the acoustic source off.
The decay rate is the time rate at a stated frequency, at which sound pressure level decreases in a room. The unit is decibel per second (dB/s).
The decay time is that elapsing time, in which the sound pressure level from a value to another drops; both values, the initial value and the goal value must be determined explicitly. A common unit for the description of the decrease of sound pressure level is the decibel per second (dB/s).
The reverberation time or the time of reverberation is defined as the time it takes for the SPL (sound pressure level) to decay to one-thousandth (! not millionth !) of its former value, a 60 dB reduction, hence called the RT60 of the space.
Sometimes it is also called decay time.
Calculation of the reverberation time after Sabine - RT 60 decay