STEREO ACOUSTIC ECHO CONTROL USING A SIMPLIFIED ECHO PATH MODEL

In handsfree tele- or video-communication, acoustic echoes arise due to the coupling between the loudspeakers and microphones. It is much more challenging to remove the undesired acous- tic echoes for stereo or multi-channel tele-communication sys- tems than for mono systems due to the non-uniqueness prob- lem. While non-uniqueness can be prevented by introducing in- dependent distortions into the left and right loudspeaker signals, stereo echo cancellation is more challenging in terms of con- vergence speed and computational complexity than mono echo cancellation. The proposed stereo echo control algorithm cir- cumvents the non-uniqueness problem by using simplified echo path models consisting of delays and short-time spectral modi- fication. It is shown that for reasonably symmetric systems the left and right echo path models are similar enough that a single echo path model can be used for estimating the total echo power spectrum and a gain filter for removing the echo from the mi- crophone channels. The proposed algorithm is also applicable to multi-channel systems and the computational complexity is very low.