Realization of wide-band directivity with three microphones

In order that the speech recognition system might have a high performance i n the noisy environment, the directional microphone arrays at the input of the system have been broadly investigated. The purpose of this study is to develop a new wide-band directional microphone system in view of advancing to an adaptive one afterwards. In the proposed system, three microphones ar e arranged on a straight line and the beamforming is accomplished in such a way that the output value of the middle microphone is added to the integra ted value of the difference between two microphones at bath sides. In this study, the signal processing of microphone outputs is implemented by using active RC circuits. Finally, the objective directivity can be experimentall y obtained in wide frequency ranges required for the speech recognition.