A subband acoustic echo canceller using the NLMS algorithm with quasi-orthonormal initialization scheme

This paper presents the normalized least mean square (NLMS) algorithm with quasi-orthonormal initialization scheme to overcome slow convergence due to the correlated speech signals in a subband acoustic echo canceller (SAEC). The quasi-orthonormal initialization scheme is realized by a set of the causal sine vectors which are the low-pass filtered impulse signals at different time-scaled positions. The NLMS algorithm after our initialization processing can immediately predict the outputs of the loudspeaker-room-microphone (LRM) system according to the inputs. Especially, the initialization processing takes a short period which is equivalent to the length of impulse response of the LRM system. The computer simulation results illustrate that the SAEC using the proposed initialization scheme can easily achieve echo return loss enhancement (ERLE) of 22 dB after fast initialization, and obtain 10 dB improvement than the conventional ones