Options
2018
Conference Paper
Titel
On the spatial coherence of residual echoes after stft-domain multi-microphone acoustic echo cancellation
Abstract
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.