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Multiple-Channel Reverberation (MCR)

 

MCR is a feedback system for the prolongation of reverberation. With a multitude of microphones, the equipment picks up the diffuse sound field under the ceiling, amplifies each single microphone signal and emits it via the corresponding loud speaker back into the hall. Since the spatial hearing experience also depends on reflections from the sides, in addition to installing them in the ceiling, loud speakers have to be installed along the walls.

Likewise, it is necessary to distribute loud speakers around the stage, thus amplifying the diffuse sound field in that area and supporting the interaction of the orchestra members. The room itself, as well as the required sound level of the reverberation field and the desired reverberation time define how many channels are needed. On the one hand, the supplied sound energy has to correspond to the given sound absorption; on the other hand, the feedback must not result in partial overloading of a channel, since minor feedback effects already affect the reverberation.
Reverberation prolongation with MCR is based on the insight that within a diffuse sound field the energy distribution of sound and the reverberation time are directly related. If the current diffuse sound field is amplified, i.e. supplied with additional energy (which partly substitutes the sound energy absorbed by the limiting surfaces), the reverberation time of the room is prolonged accordingly. The MCR system was developed and delivered by Philips (see: de Konig, S. H.: The MCR-System - multiple-channel amplification of reverberation, in: Philips Tech. Rev. 41 (1983/84), pp. 12-23).