Estimating the Delay and Coloration Effect of the Acoustic Echo Path for Low Complexity Echo Suppression

Acoustic echoes arise whenever there is acoustic coupling between a loudspeaker and a microphone. A traditional solution for eliminating the undesired echo signal is an acoustic echo canceler (AEC), which identifies the echo path between a loudspeaker and a microphone by means of an adaptive filter. The echo signal can be canceled successfully when the modeling filter approaches the true echo path. Another way to mitigate the echo effect is through echo suppression. Unlike an AEC, an acoustic echo suppressor (AES) achieves echo attenuation by means of spectral modification. In this paper, we propose an AES without a need for the computationally complex task of acoustic echo path estimation. Instead of identifying the echo path impulse response, the proposed method estimates only the properties of the echo path which are needed for effective echo suppression. These are a delay parameter and a filter mimicking the coloration effect of the echo path on the loudspeaker signal. The gain filter for the AES is computed using the estimated delay and coloration effect filter. Simulations and experiments using a real-time telecommunication system indicate that the proposed scheme is effective for suppressing echo, supports duplex communication, and is less sensitive to echo path changes than a conventional AEC.