| 摘要 |
PROBLEM TO BE SOLVED: To realize the novel performance of sound by arranging a super- directional speaker irradiating an acoustic wave to a wall surface in a ground of attraction such as a haunted house or the like, and moving the destinations on the wall surface, of the acoustic wave irradiated from the super-directional speaker toward the wall surface. SOLUTION: In an internal space 1 comprising a passage surrounded by a wall surface 2, a wall surface 3 and a wall surface 4, of a ground of attraction, a parametric speaker 20 as a super-directional speaker provided with a driving source 20A rotatably driven in the horizontal direction to the wall surface 4 opposite to the wall surface 2, is mounted on the wall surface 2. The audible acoustic wave of remarkably high directivity is generated when the audible sound is generated by the frequencies of f1-f2 produced by the interference of two supersonic waves by using the unaudible supersonic waves which can not be heard. By moving the destinations E-G to the wall surface 4 of this acoustic wave, the direction that the sound is gradually close, can be given to a person D who is going to open a door.
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