Measurements of Reverberation Time

Although the practice may not be satisfactory in all instances, it is common to regard reverberation time as the time it takes a sound which has reached maximum intensity in a room to decrease to inaudibility after the emitting source has been discontinued. This time may be approximately determined by loudly blowing some wind instrument such as a trombone or an organ pipe in a room and, after the sound has reached the maximum intensity, suddenly ceasing to blow and observing with a stopwatch the time it takes for the sound to become inaudible. Accurate instrumental methods of measuring reverberation time have been devised.*

Sabine early recognized that both the absorption coefficients of materials and the reverberation periods for rooms varied with the frequency used in performing the tests. The test frequency should accordingly be specified when such data are presented.