Abstract
Acoustic echo that can substantially undermine speech quality is one of the key issues one must address in practical telecommunication systems. Distinct from conventional mono-channel acoustic echo cancellation (AEC) techniques, this study proposes an acoustic echo jammer (AEJ) that takes advantage of beamforming to nullify the echo path. Highly directional microphone array is designed to focus on the near-end speaker and suppress the echo from the far-end as well as noise and interference from the back ground. However, various forms of system deviations, channel mismatch, sensor location error, and pointing error, severely degrade the performance of array beamformer. To cope with these deviations, generalized sidelobe canceller (GSC) not only adaptively compensates and calibrates the system errors but also suppresses the interference of sidelobe. Simulations and Automatic Speech Recognition (ASR) experiment imply the speech quality enhancement of array beamformer. Objective tests of echo cancellation performance metric ERLE (Echo Return Loss Enhancement) and Perceptual Evaluation of Speech Quality (PESQ) are calculated to compare several implementation approaches. In addition, subband (SB) implementation is employed to improve the processing efficiency. Experimental investigations show that with the beamformer, the cancellation performance can be significantly increased, as compared to conventional AEC.