We present a novel approach for real-time multichannel speech enhancement in environments of nonstationary noise and time-varying acoustical transfer functions (ATFs). The proposed system integrates adaptive beamforming, ATF identification, soft signal detection, and multichannel postfiltering. The noise canceller branch of the beamformer and the ATF identification are adaptively updated online, based on hypothesis test results. The noise canceller is updated only during stationary noise frames, and the ATF identification is carried out only when desired source components have been detected. The hypothesis testing is based on the nonstationarity of the signals and the transient power ratio between the beamformer primary output and its reference noise signals. Following the beamforming and the hypothesis testing, estimates for the signal presence probability and for the noise power spectral density are derived. Subsequently, an optimal spectral gain function that minimizes the mean square error of the log-spectral amplitude (LSA) is applied. Experimental results demonstrate the usefulness of the proposed system in nonstationary noise environments.
This article is part of the series Signal Processing for Acoustic Communication Systems.
An Integrated Real-Time Beamforming and Postfiltering System for Nonstationary Noise Environments
1 Department of Electrical Engineering, Technion – Israel Institute of Technology, Haifa 32000, Israel
2 School of Engineering, Bar-Ilan University, Ramat-Gan 52900, Israel
3 Lamar Signal Processing, Ltd., Andrea Electronics Corp., P.O. Box 573, Yokneam Ilit, 20692, Israel
EURASIP Journal on Advances in Signal Processing 2003, 2003:936861 doi:10.1155/S1110865703305050
The electronic version of this article is the complete one and can be found online at: http://asp.eurasipjournals.com/content/2003/11/936861
Received: | 1 September 2002 |
Revisions received: | 6 March 2003 |
Published: | 5 October 2003 |
© 2003 Copyright © 2003 Hindawi Publishing Corporation
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