Reverberators for use in wide band assisted reverberation systems

Abstract

A multi-channel reverberation system has a substantially constant multi-channel power gain at audio frequencies and comprises multiple signal inputs, one for each input channel, a number of comb filter networks connected to each signal input, each comb filter network including a feed forward stage, a cross-coupling network cross-coupling the comb filters to increase the reverberation echo density, and multiple signal outputs, one for each output channel. Preferably the feed forward stage of each comb filter provides a substantially constant multi-channel power gain at audio frequencies and the cross-coupling matrix is an orthogonal cross-coupling matrix cross-coupling a number of single channel allpass comb filters, positioned immediately before or after the delay lines, to create a multi-channel allpass comb filter with a unitary transfer function matrix at all frequencies.

1. A multi-channel reverberation system comprising:
 multiple signal inputs, one for each input channel;    a number of feed back comb filter networks connected one to each signal input, each comb filter network including a feed forward stage to provide a substantially constant multi-channel power gain at audio frequencies;    a cross-coupled network cross-coupling the comb filters to increase the reverberation echo density;    and multiple signal outputs, one for each output channel.    
     
     
       2. A multi-channel reverberation system according to  claim 1 , wherein the feed forward stage of the comb filters provides a transfer function matrix which is unitary at each frequency in the audio range. 
     
     
       3. A multi-channel reverberation system according to  claim 1 , wherein the cross-coupling matrix is an orthogonal cross-coupling matrix cross-coupling a number of single channel allpass comb filters, positioned immediately before or after the delay lines, to create a multi-channel allpass comb filter with a unitary transfer function matrix at all frequencies. 
     
     
       4. An assisted reverberation or room acoustic enhancement system, comprising:
   multiple microphones positioned to pick up reverberant sound in a room,        multiple loudspeakers to broadcast sound into the room, and        a multichannel reverberator, comprising:        multiple signal inputs, one for each input channel and which receive similar bandwidth signals from the microphones;        a number of feed back comb filter networks connected one to each signal input, each comb filter network including a feed forward stage to provide a substantially constant multi - channel power gain at audio frequencies;        a cross - coupling network cross - coupling the comb filters to increase the reverberation echo density;        and multiple signal outputs, one for each output channel.     
     
     
       5. An assisted reverberation or room acoustic enhancement system according to  claim 4 , wherein the feed forward stage of the comb filters provides a transfer function matrix which is unitary at each frequency in the audio range. 
     
     
       6. An assisted reverberation or room acoustic enhancement system according to  claim 4 , wherein the cross- coupling matrix is an orthogonal cross - coupling matrix cross - coupling a number of single channel allpass comb filters, positioned immediately before or after the delay lines, to create a multi - channel allpass comb filter with a unitary transfer function matrix at all frequencies.   
     
     
       7. A multi- channel unitary reverberator comprising:      multiple signal inputs, one for each input channel,        a number of feedback comb filter networks connected one to each signal input, each comb filter network including a feed forward stage to provide a substantially constant multi - channel power gain at audio frequencies, wherein there is one multiplier in each channel residing in both the feed forward and feedback networks,      a cross- coupling network cross coupling the comb filters to increase the reverberation echo density, and        multi signal outputs, one for each output channel.