Microphone array system for speech recognition

This paper proposes a microphone array system which realizes the following important functions for speech recognition: i) SNR improvement, ii) flat spectrum response for an arbitrary speaker position, and iii) speech period detection in noisy speech. This microphone array system features time delay estimation using prewhitening signal processing, an optimally weighted delay-and-sum array, and speech period detection (called MLD) based on the level difference between signals before and after array processing. Word recognition experiments performed in the presence of crowd noise demonstrate that the proposed system has great robustness against noise than does the system with a conventional directional microphone and a speech period detection method.