| 摘要 |
PROBLEM TO BE SOLVED: To overcome such a problem that it is difficult to set the parameters, e.g. the aperture dimension of a sound hole, material constants of an acoustic resistance material, and the like, appropriately such that directivity is exhibited over the entire band of an audible sound emitted from a speaker, and that such a speaker is not suitable for a voice announce system emitting an audible sound directively. SOLUTION: The super-directive speaker comprises a sound source 1 generating an audible sound signal, a sound emission controller 2 for controlling the sound emission characteristics of an audible sound signal utilizing a carrier belonging to an ultrasonic band, an amplifier 3 for amplifying an audible sound signal having sound emission characteristics controlled by the sound emission controller 2, and a speaker 4 receiving an audible sound signal amplified by the amplifier 3 and emitting an audible sound.
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