Publications – Details
The Tight Relation between Acoustic Echo Cancellation and Residual Echo Suppression by Postfiltering
- Authors:
- Gerald Enzner, Rainer Martin, and Peter Vary
- Book Title:
- Konferenz Elektronische Sprachsignalverarbeitung (ESSV)
- Venue:
- Dresden, Germany
- Event Date:
- 0.-0.0.2002
- Organization:
- ITG
- Date:
- Sept. 2002
- Language:
- English
Abstract
In the acoustic environment of mobile hands-free telephones we have to expect low signal-to-noise ratios and considerable acoustic feedback at the local microphone. Adaptive filters are typically used for feedback cancellation. However, there is often residual echo due to insufficient performance of the echo canceler. It has been shown in [Gustafsson, Martin, Vary (1998)] that the postfilter for combined residual echo and noise suppression improves the feedback attenuation in the duplex connection. In this paper, we will clarify differences and similarities between echo cancellation and postfiltering: Echo cancellation in principle performs in-phase feedback attenuation, whereas postfiltering performs suppression of residual echo irrespective of the signal phase. Interestingly, echo cancellation and postfiltering for residual echo suppression rely on the same control parameter, the residual echo power. The assessment of this parameter is indeed the essential problem in echo control systems. In that respect, echo cancellation and postfiltering are reduced to the same estimation problem. We will demonstrate this fact in the example of a frequency-domain implementation.
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