Direction of arrival estimation using nonlinear microphone array

This paper describes a new method for estimating the direction of arrival ( DOA) using a nonlinear microphone array system based on complementary beamf orming. Complementary beamforming is based on two types of beamformers desi gned to obtain complementary directivity patterns with respect to each othe r. In this system, since tilt resultant directivity pattern is proportional to the product of these directivity patterns, the proposed method can be u sed to estimate DOAs of 2(K - 1) sound sources with K-element microphone ar ray. First, DOA-estimation experiments are performed using both computer si mulation and actual devices in real acoustic environments. The results: cla rify that DOA estimation for two sound sources can be accomplished by the p roposed method with two microphones. Also, by comparing the resolutions of DOA estimation by the proposed method and by the conventional minimum varia nce method, wt can show that the performance of the proposed method is supe rior to that of the minimum variance method under all reverberant condition s.