LOUDSPEAKER DEVICE AND METHOD FOR DRIVING THE SAME, AND AUDIO SIGNAL TRANSMITTER/RECEIVER

摘要

An audio signal outputted from a sound source is modulated into a signal with a frequency in a frequency band higher than the audio frequency band by a modulator. An ultrasonic wave generating device is driven by the signal whose frequency is modulated by the modulator. The modulator modulates the audio signal outputted from the sound source into signal with a first frequency and signal with a second frequency which is different from the first frequency. By driving the ultrasonic wave generating device by thus modulated signals, a frequency component corresponding to the difference between the ultrasonic wave with the first frequency and the ultrasonic wave with the second frequency is heard as an audio sound. Since the ultrasonic wave is generated by the ultrasonic wave generating device, a super directivity can be realized.