reverberation time: Denotes an essential size in the room acoustics. It indicates the time within which the level of a noise signal or an impulse has dropped by 60 dB.
Since the ear no longer assigns reverberation components that lag behind in time to the original sound event and (depending on the listening room considered) ambient noise often masks the late reverberation, the early reverberation is more important for the subjective perception. Therefore, the Early Decay Time (EDT) is also measured: the time in which the level decreases by 10 dB. The reverberation time depends on the frequency, because high frequencies are easier to dampen than low ones and their level therefore drops faster.