A multi-block frequency-domain adaptive filter in an acoustic echo canceller as applied to a full-duplex speakerphone includes convolving a received reference signal with a linear room model to generate an echo free signal for transmission which, in turn, is used to adapt the coefficients of the room...http://www.google.de/patents/US5526426?utm_source=gb-gplus-sharePatent US5526426 - System and method for an efficiently constrained frequency-domain adaptive filter
