Microphone array apparatus

DETAILED DESCRIPTION It is a general object of the present invention to provide a microphone array apparatus in which the above disadvantages are eliminated.
A more specific object of the present invention is to provide a microphone array apparatus capable of stably and precisely suppressing noise, emphasizing a target sound and identifying the position of a sound source.
The above objects of the present invention are achieved by a microphone array apparatus comprising: a microphone array including microphones (which correspond to parts indicated by reference numbers 1-1-1-n in the following description), one of the microphones being a reference microphone (1-1); filters (2-1-2-n) receiving output signals of the microphones; and a filter coefficient calculator (4) which receives the output signals of the microphones, a noise and a residual signal obtained by subtracting filtered output signals of the microphones other than the reference microphone from a filtered output signal of the reference microphone and which obtain filter coefficients of the filters in accordance with an evaluation function based on the residual signal.
With this structure, even when speech of a speaker corresponding to the sound source and the noise are concurrently applied to the microphones, the crosscorrelation function value is reduced so that the noise can be effectively suppressed and the filter coefficients can continuously be updated.
The above microphone array apparatus may be configured so that it further comprises: delay units (8-1-8-n) provided in front of the filters; and a delay calculator (9) which calculates amounts of delays of the delay units on the basis of a maximum value of a crosscorrelation function of the output signals of the microphones and the noise.
Hence, the filter coefficients can easily be updated.
The microphone array apparatus may be configured so that the noise is a signal which drives a speaker.
This structure is suitable for a system that has a speaker in addition to the microphones