"How long before there is no echo".
Simple explanation of the reverberation time:
When a person speaks, they emit sound waves. These sound waves are reflected in the room by a wall, for example - there is an echo.
In very simplified terms, the reverberation time of the
Period of time from the end of speaking to the time when you no longer hear an echo.
A precise definition of reverberation time expresses this somewhat more scientifically:
Reverberation time (RT) is a measure of the amount of reverberation in a room. It indicates the time interval within which the sound pressure level in a room decreases to a fraction when the sound source is suddenly silenced. RT60 corresponds to a decrease of the sound pressure level by 60 dB.
In the attached example, it takes 1 second for the sound pressure level to decrease by 60dB. The reverberation time (RT60) is therefore 1 second.