Insight into a phase modulation technique for signal decorrelation in multi-channel acoustic echo cancellation

Abstract

High coherence between the loudspeaker signals in a multichannel communication set-up is known to be detrimental to the performance of a multi-channel acoustic echo cancellation (MC-AEC) system. The MC-AEC performance can be improved by decorrelating the loudspeaker signals prior to their reproduction. The decorrelation process can however degrade the subjective sound quality. A technique which has proven to provide a good trade-off between the MC-AEC performance enhancement and the subjective quality of the decorrelated signals, is applying a time-varying and perceptually motivated phase modulation in the sub-band domain. The aim of this paper is to provide further insight into this technique by analysing the influence on the signals' coherence as well as the MC-AEC performance in terms of its convergence speed.