ACOUSTIC REPRODUCING APPARATUS

摘要

PROBLEM TO BE SOLVED: To provide an acoustic reproducing apparatus for utilizing an ultrasonic wave to reproduce an audible tone with strong directivity that solves a defect that a distance from an ultrasonic wave generating element to a reproduction point of the audible tone is too long. SOLUTION: In the acoustic reproduction method whereby a plurality of ultrasonic wave generating elements arranged in a form of a disk emit an ultrasonic wave signal subjected to amplitude-modulation by an audible signal and a super-directivity is realized in a desired direction by using the self demodulation effect utilizing the nonlinearity of a medium, a first reflecting plate placed a distance L away from the disk in a vertical direction at an angleψ(=arctan(2a/L)2) with respect to a direction horizontal to the disk reflects the ultrasonic wave onto a plane including the disk, a second reflecting plate is placed on a plane including the disk and a third reflecting plate is placed on a plane at a distance of L in parallel with the plane including the disk multiply reflect the reflected ultrasonic wave, and a fourth reflecting plate whose mount angle is variable reflects the multiply reflected ultrasonic waves into a desired direction for reproduction of the sound in the desired direction. COPYRIGHT: (C)2004,JPO