Speech enhancement based on multiple directivity patterns using a microphone array

A novel speech segregation method using a microphone array with multiple directivities is proposed and applied to speech recognition under existence of disturbance speech. Conventional microphone array techniques use only single directivity of their own. It is very difficult for this kind of array technique to remove the influence of the disturbance. In our method, redundant simultaneous equations of the amplitudes of sound sources are generated by using these multiple directivities. The solution of these equations gives good estimates of disturbances. The spectral subtraction is applied with these estimates of disturbances, and the perfect enhancement of target speech is performed. The experimental results of double talk recognition with 20 K vocabulary show that the proposed enhancement technique is effective to achieve 45 % error reduction.