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 paper 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. With the beamformer, the cancellation performance can be significantly enhanced, as compared to conventional AEC. However, various forms of system deviations can arise due to channel mismatch, sensor location error, and pointing error. To cope with these deviations, a robust AEJ is developed on the basis of an adaptive generalized sidelobe canceller (GSC). The robust AEJ comprises a fixed beamformer (FBF), a blocking matrix (BM) and a multiple-input canceller (MC) by which a null is adaptively placed at the direction of the incident interference. In addition, subband (SB) implementation is employed to enhance the processing efficiency. Objective and subjective tests are conducted to compare several implementation approaches of the proposed systems. The cancellation performance metric ERLE (Echo Return Loss Enhancement) have attained 26 dB and 30 dB with the AEJ-SB- AEC and the SB-GSC, respectively, in comparison with 15 dB with the conventional AEC. Copyright© (2013) by Austrian Noise Abatement Association (OAL).