An acoustic echo canceller using subband sampling and decorrelation methods

An acoustic echo canceller based on signal decorrelation and subband techniques is developed. A decorrelation algorithm is combined with a variable loop gain method. Echo cancellation characteristics superior to those of the conventional normalized least-mean-square (NLMS) adaptation algorithm are obtained through computer simulation. The implementation of an acoustic subband echo canceller with high speech quality is demonstrated. Experiments confirm echo cancellation in excess of 40 dB over the 7 kHz frequency band using hardware with a total of 4000 tap finite impulse response (FIR) filters. The decorrelation algorithm increases convergence speeds for colored signals by about three times, and for speech signals by more than two times over those of the NLMS algorithm