EURASIP Journal on Applied Signal Processing 
Volume 2002 (2002), Issue 4, Pages 432-443
doi:10.1155/S1110865702000690

SVD-Based Optimal Filtering Technique for Noise Reduction in Hearing Aids Using Two Microphones

Jean-Baptiste Maj,1,2 Marc Moonen,2 and Jan Wouters1

 1Lab. Exp. ORL, Katholieke Universiteit Leuven, Kapucijnenvoer 33, Leuven 3000, Belgium
2ESAT-SISTA, Katholieke Universiteit Leuven, Kasteelpark Arenberg 10, Leuven B 3001, Belgium
Received 14 March 2001; Revised 30 October 2001

Abstract

We introduce a new SVD-based (Singular value decomposition) strategy for noise reduction in hearing aids. This technique is evaluated for noise reduction in a behind-the-ear (BTE) hearing aid where two omnidirectional microphones are mounted in an endfire configuration. The behaviour of the SVD-based technique is compared to a two-stage adaptive beamformer for hearing aids developed by Vanden Berghe and Wouters (1998). The evaluation and comparison is done with a performance metric based on the speech intelligibility index (SII). The speech and noise signals are recorded in reverberant conditions with a signal-to-noise ratio of 0 dB and the spectrum of the noise signals is similar to the spectrum of the speech signal. The SVD-based technique works without initialization nor assumptions about a look direction, unlike the two-stage adaptive beamformer. Still, for different noise scenarios, the SVD-based technique performs as well as the two-stage adaptive beamformer, for a similar filter length and adaptation time for the filter coefficients. In a diffuse noise scenario, the SVD-based technique performs better than the two-stage adaptive beamformer and hence provides a more flexible and robust solution under speaker position variations and reverberant conditions.