Stereophonic acoustic echo cancellation and two-channel adaptive "ltering: an overview

Stereophonic acoustic echo cancellation (SAEC), has been studied since the early 1990s. Because of spatial realism, two-channel audio is now becoming more interesting in a number of hands-free applications such as teleconferencing, multi-participant desktop conferencing, and televideo gaming. From a theoretical point of view, SAEC di!ers considerably from traditional mono echo cancellation since the normal equation to be solved by the adaptive algorithm is singular. Of course, this also a!ects the practical considerations that have to be made when designing a SAEC system, e.g. choice of adaptive algorithm. This paper reviews the basic theory behind SAEC, solutions to the singularity problem, and a number of classical two-channel adaptive algorithms suited to the problem. Copyright ( 2000 John Wiley & Sons, Ltd. KEY WORDS: echo cancellation; stereophonic sound; acoustic; desktop conferencing; adaptive "lters 1