Double-talk detection in acoustic echo cancellers using zero-crossings rate

Abstract

We propose a new method to detect double-talk and control filter adaptation in an acoustic echo canceller (AEC). The method is based on computing the zero-crossings rate (ZCR) of the AEC output and comparing it against a suitably-chosen threshold. As the ZCR values falls below the threshold, double talk is declared and the AEC filter adaptation is either slowed down or halted. The zero crossings are very easy to compute by observing the sign changes of two consecutive samples from the output of the AEC. In contrast to most existing methods, the computational burden of the proposed method is minimal and it can, therefore, be conveniently implemented on a low-power, low-resource processor. This computational simplicity is enjoyed without sacrificing for any AEC performance. We will illustrate effectiveness of the proposed method by comparing against the existing state of the art and present guidelines on choosing parameters for computing the sample-by-sample ZCR.