The research group of authors has been developing completely new loudspeaker constructions which are driven by piezoelectric ultrasonic motors. This paper proposes two sorts of applications of piezoelectric linear actuators to both direct radiator and horn loudspeakers. A direct-radiator loudspeaker with a cone radiator driver by piezoelectric actuators shows smooth frequency characteristics in low frequency region because its radiating motion includes no significant resonance in the working frequency region. Therefore, it is useful for radiation of the lowest frequency part of audio signal. A horn loudspeaker by the same actuators works in rather moderate frequency region which is higher than the cut-off frequency of horns of ordinary size.
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