| 摘要 |
<P>PROBLEM TO BE SOLVED: To enhance acoustic characteristics so as to obtain a rotational curved-surface directional characteristic of a sector section in the upper-side direction of a plane, when a pair of omnidirectional microphones are disposed apart by a predetermined distance on the upper side of the plane. Ž<P>SOLUTION: A first and a second communication-channel forming circuits 4, 5 are controlled on the basis of the detection result of a comparator 2 that detects the phase difference of a sound wave entering a pair of microphones 1a, 1b. The channel-forming circuits 4 and 5 constitute communication channels from a primary subtracting circuit 7 to a tertiary adding circuit 9 and a secondary subtracting circuit 10, as well as from the tertiary adding circuit to an output terminal 11, when an attained level in another microphone connected to a delay means 8 is smaller than that in one microphone. Further, the circuits 4 and 5 constitute the communication channels from a secondary adding circuit to the tertiary adding circuit and the secondary subtracting circuit, as well as from the secondary subtracting circuit to the output terminal, when the attained level in another microphone is larger than that in one microphone. Ž<P>COPYRIGHT: (C)2010,JPO&INPIT Ž
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