reverberation time (RT)
Reverberation time(RT) is the time of reverberation of a sound after the sound source has been switched off. The reverberation time is a defined quantity that results from the decay time after a continuous sinusoidal sound is switched off. It is the time that elapses until the sound level decreases by 60 dB after a sine tone of 800 Hz or 1 kHz is switched off. This corresponds to a sound level reduction by a factor of 1,000:1.
The prerequisite for measuring the reverberation time is that the room is steady, which means that the sine tone has propagated throughout the room. The room acoustic parameter that has a direct influence on sound quality is the RT60 value or T60 value, derived from Reverberation Time (RT) or reverberation time, related to the decrease in sound level by 60 dB.
This characteristic value was determined by Wallace C. Sabine in a formula. According to this formula, the room volume and the absorbing surfaces of walls, ceilings and floors with their absorption coefficient are included in the calculation. The reverberation time is frequency-dependent and becomes shorter at higher frequencies. It depends on the room and the room acoustics and should be between 100 ms and 500 ms.