| 摘要 |
PROBLEM TO BE SOLVED: To obtain the device whose directivity will not deteriorate, even when a frequency of a sound wave gets lower by applying processing using finite space coordinates based on a regularity of an optional plane to outputs of a plurality of microphone units placed on the plane with the regularity so as to provide the directivity to the outputs. SOLUTION: The outputs of a plurality of microphone units 11, 12, 13, 14, 15 placed on a closed spherical plane are processed by using the polar coordinates in a three-dimensional polar coordinate space along with the enclosed plane, where a plurality of the microphone units are placed. Then reference data referred to as data obtained when it is assumed a planar wave comes only from a direction defined as a reference direction are compared with actually obtained measurement data to produce directivity. A plurality of microphone rings, each consisting of a plurality of the microphone units, are placed not overlapping with each other in a way that the centers of the rings are coincident with each other to cause all the units to distribute on the spherical face.
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