An Analysis of the Regenerative Reverberation Effects of Acoustic Feedback in Rooms

The behaviour of a microphone, amplifier, loudspeaker ‘channel’ in the low frequency modal environment of a large enclosure is examined. A pulse statistics analysis of the channel inside a tube with absorbent ends is derived and adapted to predict the regenerative reverberation time in three dimensions. The regenerative reverberation time at any one frequency is a function of the loop gain. Since the air component of the loop gain is controlled by the frequency and space sensitive modal coupling process of the channel the reverberation time is only predictably controlled at one frequency, the feedback or principle regeneration frequency.