Enhanced Partitioned Stereo Residual Echo Estimation

For convenient hands-free telecommunication systems echo cancelers with a low delay are desirable. Since such systems have to cope with long room impulse responses (RIRs) common echo cancelation techniques often suffer from slow convergence or introduce large delays. An algorithm for acoustic echo cancelation (AEC) has to compensate the influence of RIRs of several thousand sampling points. Thus for frequency domain algorithms long DFT-lengths are needed to cover the whole influence of the RIRs. Approaches in the partitioned frequency domain overcome this drawback. Our contribution describes a combined echo cancelation system in the partitioned frequency domain containing a conventional stereo AEC enhanced by a post-filter which requires a reliable residual echo estimate. This contribution focuses on minimizing the estimation bias introduced by partitioned residual echo estimation. For this purpose an optimal smoothing factor for the residual echo differential system will be derived.