A multi-channel acoustic cancellation system 40 with, for example, stereo
speakers and a pair of microphones in the transmitting and receiving rooms (11
and 21) has time varying all-pass filters (45, 47) in the signal
path between the microphones (13, 15) in the transmitting room (11)
and the speakers (27, 29) in the receiving room (21) to provide decorrelation.
