| 摘要 |
PROBLEM TO BE SOLVED: To reduce the cost and to realize the miniaturization by simplifying the configuration of ultradirectivity used for a video camera or the like. SOLUTION: A n-sets of microphone units (microphones) are arranged on a line at equal intervals. On the other hand, (n-1) sets of all pass filters and (n-1) sets of adders 13 are provided. For example, let number of stages of the microphones 11 be 6 and let a value of its pitch divided by the sound velocity beτ, then in the case of input of a sound from a direction A, output signals of the microphones 11a-11e are delayed by all pass filters 12a-12e by a timeτeach, and the delayed signals are fed to an adder 13e, in which the signals are added to an output signal of the microphone 11f. In this case, since 6 sound signals are of the same phase, the output level is increased. When the sound is made incident in an oblique direction, since the phase in the adder 13e differs, the signals are cancelled.
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