Fundamentals of room acoustics

Abstract

A reverberation can be heard in an enclosed room if a sound source, which was in operation for a longer period, is suddenly turned off. Its duration depends on the room volume and the room’s interior design; the reverberation time is short in small rooms and in rooms which have large absorbing surfaces. Large volumes with less absorption have reverberation times which can easily extend to a couple of seconds. During a period of 2 s, for instance, the sound travels a distance of nearly 700m and hits the room surfaces several times; the sound waves are reflected several times at the walls under different angles. Each reflection at a (rigid) plane surface can be regarded as coming from a sound source which is mirrored at the wall.