Microphone array for increasing mutual information between sound sources and observation signals

We investigated the basic principle of how spatial signals should be captured with a microphone array to estimate each source signal and its practical implementation. Most conventional studies on array signal processing have been focused on the design of beamforming and Wiener filters. To achieve further effective noise reduction, designing an optimum array structure to segregate a target from other noises is necessary. We found the optimum structure of the spatial correlation matrix to estimate each source signal. This is achieved by receiving signals whose eigenvalues of the spatial correlation matrix are homogenized. To homogenize the eigenvalues of the spatial correlation matrix while maintaining a short impulse response length, we propose an array structure composed of parabolic reflectors and 96 microphones. Through experiments using the proposed array structure, we confirmed that the eigenvalues of the spatial correlation matrix was asymptotically homogenized and that sharp directivity could be formed.