Development of a multi-beam array microphone for multi-channel pickup of sound fields and its applications to room acoustics

A new multi-beam array microphone (MAM for short) has been developed. The MAM is composed of four concentric rings, each of which has 12 microphones elements, and a common center microphone. The MAM synthesizes the output phase of each microphone by compensating for the path differences. It has 12 main beams that point in 12 different directions at intervals of 30 deg in the horizontal plane. These main beams are sharp over a wide frequency range. By utilizing these characteristics, the MAM can be applied to many fields such as precise acoustic measurement of sound fields, automatic talker locations, and beam steering. When reproducing the original sound field by this system, 12 loudspeakers arranged in a circle around a central point are connected to the corresponding 12 outputs of the MAM. A new acoustical parameter based on spatial correlation of the sound field (correlation between the 12 MAM outputs) is proposed by utilizing the MAM.