Evaluation of microphone array based on diffused sensing with various filter design methods

We investigated methods for achieving sharp directivity over a broad frequency range by using a multichannel inverse filter. We previously proposed the diffused sensing method for segregating sound sources by decorrelating the transfer functions of each sound source by placing an array in a diffused acoustic field. Because many transfer functions must be measured in advance in our previous method, we discuss how to achieve sharp directivity based on diffused sensing using only a few pre-measurements. As a physical phenomenon, transfer functions are expected to be decorrelated automatically in a diffused acoustic field. By exploiting this property, we found that sharp directivity could be achieved with the multichannel inverse filter, which dereverberates the target paths only. Through simulations, we show that to achieve sharp directivity, the length of the multichannel inverse filter should be the same as the impulse response length.