A Directional Noise Suppressor with a Specified Constant Beamwidth

Abstract

This paper proposes a directional noise suppressor with a specified constant beamwidth for directional interferences and diffuse noise. A directional gain is calculated based on interchannel phase difference and combined with a spectral gain commonly used in single-channel noise suppressors. The beamwidth can be specified as passband edges of the directional gain. In order to implement frequency-independent constant beamwidth, frequency-proportionate directional gains are defined for different frequencies as a constraint. Evaluation with signals recorded by a commercial PC demonstrates good agreement between the theoretical and the measured directivity. The signal-to-noise ratio improvement and the PESQ score for the enhanced signal are improved by 24.4dB and 0.3 over a conventional noise suppressor. In a speech recognition scenario, the proposed directional noise suppressor outperforms both the conventional nondirectional noise suppressor and the conventional directional noise suppressor based on phase based T/F filtering with a negligible degradation in the word error rate for clean speech.