Wide-band and low noise directional microphone system realization by frequency band decomposition method

摘要

The recognition rate of a speech recognition system of hand-free decreases remarkably by the back ground noise in the crowd, the inside of a car and so on. To cope with this, it is required to reserve the high S/N rate in the input part of the system. In the man-machine interface of speech input of various kind, realization of a low-noise wide-band sharp directional microphone system is an important theme. The upper limit of frequency for the realization of excellent beamforming, the lower limit related to the specific noise and the characteristic deterioration of the dispersion of microphone sensitivities accompany multi-microphone system. To solve the problems we focus on the stable realization of a wide-band uni-directional characteristic using the band decomposition method and apply this method to the system of the three-microphone integration. This paper describes that it is possible to realize a wide-band uni-directional microphone system with low-noise and without much effect of the dispersion of microphone sensitivities on the directional patterns.