This paper investigates the use of post-filtering algorithms for suppressing residual echo in adaptive acoustic echo cancellers, which is an important component of hands-free telephone systems. The goal of post-filtering is to enhance near-end speech corrupted by residual echo due to echo canceller under-modeling. In this paper the use of signal subspace enhancement is investigated as a post-filter structure by employing a subspace decomposition of the echo canceller error signal using the Karhunen-Loeve transform (KLT). In particular, the spectral-domain constrained (SDC) linear estimator is employed to enhance the near-end speech subspace while suppressing the residual echo subspace. Practical and low-complexity implementation considerations are discussed. Simulation results are presented comparing the approach to frequency-domain post-filtering in terms of objective near-end speech distortion and quality measures.

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Keywords Acoustic echo cancellation, Post-filtering, Residual echo suppression, Signal subspace enhancement
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Conference 2006 Canadian Conference on Electrical and Computer Engineering, CCECE'06
Gordy, J.D. (James D.), & Goubran, R. (2007). Post-filtering for residual echo suppression in under-modeled acoustic echo cancellers. In Canadian Conference on Electrical and Computer Engineering (pp. 1184–1187). doi:10.1109/CCECE.2006.277388