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On the spatial coherence of residual echoes after stft-domain multi-microphone acoustic echo cancellation

: Valero, M.L.; Habets, E.A.P.


Saruwatari, H. ; Institute of Electrical and Electronics Engineers -IEEE-:
16th International Workshop on Acoustic Signal Enhancement, IWAENC 2018. Proceedings : 17th-20th September 2018, Tokyo, Japan
Piscataway, NJ: IEEE, 2018
ISBN: 978-1-5386-8151-0
ISBN: 978-1-5386-8150-3
ISBN: 978-1-5386-8152-7
International Workshop on Acoustic Signal Enhancement (IWAENC) <16, 2018, Tokyo>
Fraunhofer IIS ()

For computational efficiency, sub-band dependencies are commonly neglected when implementing acoustic echo cancelers in the short-time Fourier transform (STFT) domain. Hereafter, regardless of the background noise level, acoustic echo transfer function estimates are constantly biased, and residual echoes remain. Given a multimicrophone setup, residual echoes can be suppressed by applying a post-filter to the output of each canceler, or, when applicable, to the output of a beamformer. In this contribution, we derive an analytic expression for the spatial coherence of residual echoes after STFT-domain multi-microphone acoustic echo cancellation to gain insight into the ability of a beamformer to reduce residual echoes. The obtained expression, as well as supporting simulations, show that the spatial coherence of residual echoes is not only related to that of the noise, but also to the spatial coherence of bias terms that result from the neglection of the sub-band dependencies.