Patent ID: 8213598

Claim:
A system for suppressing a portion of a microphone signal corresponding to a speaker audio signal played aloud in a space having a microphone therein which picks-up the speaker signal playback and generates a microphone signal, wherein a portion of the microphone signal that corresponds to the speaker audio signal playback comprises non-linear harmonic distortion, said system comprising: an acoustic echo canceller (AEC) module which suppresses some parts of the speaker signal playback found in the microphone signal and generates an AEC output signal; and a harmonic distortion residual echo suppression (HDRES) module which accepts the AEC output signal and the speaker signal, and suppresses at least a portion of a residual part of the speaker audio signal playback found in the microphone signal left unsuppressed by the AEC module, as well as at least a portion of the harmonic distortion exhibited in the AEC output signal caused by the speaker audio signal playback, to produce a HDRES output signal, wherein the HDRES program module comprises for each prescribed time-length segment of the AEC output signal in the order it is generated, sub-modules which, for each frequency sub-band in a set of pre-defined sub-bands within a prescribed overall frequency range, estimate an instantaneous value of a residual echo component of the current AEC segment being processed for the sub-band under consideration as exhibited in a prescribed signal attribute, estimate a recursive average of the residual echo component for the current AEC segment at the sub-band currently under consideration, estimate a recursive average of the AEC output signal segments for the current AEC segment at the sub-band currently under consideration, estimate a recursive average of an AEC segment noise component for the current AEC segment at the sub-band currently under consideration, estimate a gain for the current AEC segment at the sub-band currently under consideration using the recursive average estimates, wherein the gain when applied to the current AEC segment suppresses the residual echo component at the sub-band currently under consideration, and compute the product of the gain estimate for the current AEC segment at the sub-band currently under consideration, and the current AEC segment, to generate a HDRES output signal segment component for the sub-band currently under consideration, and which, combine the HDRES output signal segment components generated for each sub-band to produce a HDRES output signal segment which represents the current AEC segment.