| 摘要 |
<P>PROBLEM TO BE SOLVED: To allow a sound reproducing device having high directivity such as a parametric speaker to perform phase control with simple configuration. Ž<P>SOLUTION: An AD converter 10 samples a modulation signal for amplitude-modulating an ultrasonic signal at a predetermined sampling frequency to generate samples of the modulation signals successively. The successively generated samples of the modulation signal are stored in a storage section 20. A readout section 30 reads a plurality of samples, having predetermined time intervals, among the samples of the modulation signal from the storage section 20. An ultrasonic signal oscillator 40 oscillates an ultrasonic signal. A plurality of amplitude modulators 61, ..., 6n amplitude-modulate the ultrasonic signal by using the plurality of read samples respectively to output a plurality of modulated signals. A plurality of electroacoustic transducers 71, ..., 7n are driven with the plurality of modulated signals respectively. Ž<P>COPYRIGHT: (C)2010,JPO&INPIT Ž
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