Speech Enhancement Using a Square Microphone Array in the Presence of Directional and Diffuse Noise

Tetsuji OGAWA  Shintaro TAKADA  Kenzo AKAGIRI  Tetsunori KOBAYASHI  

IEICE TRANSACTIONS on Fundamentals of Electronics, Communications and Computer Sciences   Vol.E93-A   No.5   pp.926-935
Publication Date: 2010/05/01
Online ISSN: 1745-1337
DOI: 10.1587/transfun.E93.A.926
Print ISSN: 0916-8508
Type of Manuscript: PAPER
Category: Speech and Hearing
directional noise reduction,  diffuse noise reduction,  square microphone array,  speech recognition,  mobile devices,  

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We propose a new speech enhancement method suitable for mobile devices used in the presence of various types of noise. In order to achieve high-performance speech recognition and auditory perception in mobile devices, various types of noise have to be removed under the constraints of a space-saving microphone arrangement and few computational resources. The proposed method can reduce both the directional noise and the diffuse noise under the abovementioned constraints for mobile devices by employing a square microphone array and conducting low-computational-cost processing that consists of multiple null beamforming, minimum power channel selection, and Wiener filtering. The effectiveness of the proposed method is experimentally verified in terms of speech recognition accuracy and speech quality when both the directional noise and the diffuse noise are observed simultaneously; this method reduces the number of word errors and improves the log-spectral distances as compared to conventional methods.