| 摘要 |
PURPOSE:To prevent deterioration of a characteristic of the 2nd harmonic distortion by leading a signal of an audible frequency band to an ultrasonic wave vibrator, converting the signal into a sound wave of a definite amplitude level, irradiating the wave in a medium such as air and reproducing the original audible sound through the nonlinear effect of the medium. CONSTITUTION:A signal generated from a modulation signal source 1 of an audible frequency band is fed to an adder 4 via coefficient multiplier 2 and added to a DC component from a DC source 3 at a prescribed rate at the adder 4. The added signal is given to a half power converter 5 and to a multiplier 7 after square root processing. The signal is multiplied with a carrier having a high frequency outputted from an ultrasonic wave band oscillator 6 at the multiplier 7, and the multiplied signal is given to an ultrasonic wave vibrator array 9 via a power amplifier 8. Thus, the sound wave of a definite amplitude level having a good 2nd harmonic distortion characteristic is generated from the ultrasonic wave vibrator array 9 and the wave is reproduced into an audible tone by the nonlinear effect of the medium. |
