PARAMETRIC LOUDSPEAKER

PROBLEM TO BE SOLVED: To provide a parametric loudspeaker which achieves a power consumption comparable to that in the case of PWM modulation, and never has a trouble such as the change in piezoelectric loudspeaker's timbre and the like because of operation with a fixed pulse width as in the case of AM modulation.SOLUTION: The parametric loudspeaker used for a vehicle-approach-reporting device includes: a report sound signal generation part 7 which generates an electric signal of report sound; a level-determination part 1 which determines the level of an audible tone signal according to a method of dividing the audible tone signal level into high to low levels; a serial pulse conversion part 2 which outputs ultrasonic pulse signals X, the number of which depends on the level thus determined; and a power amplifier 4 which drives a piezoelectric loudspeaker 3 by the output ultrasonic pulse signals X. In the parametric loudspeaker, the power consumption by the power amplifier 4 can be suppressed as in the case of PWM modulation because the power amplifier 4 is operated according to the presence or absence of the pulse signals. Since the pulse width is fixed at all times, a sound pressure that the piezoelectric loudspeaker 3 generates has no deviation with respect to an input audible tone signal as in a parametric loudspeaker for which AM modulation adopted, and therefore the timbre and the like are unchanged.