Development of an aerial ultrasonic sound source with a truncated cone-shaped reflective plate on a circular transverse vibrating plate

Ultrasound technology that delivers a powerful sound wave with sharp directivity over a long distance in the air is required. As a sound source for this purpose, authors devised an ultrasonic sound source with a new shape in which the opening area is smaller than that of the complex reflective plate, and a reflective plate whose size is equivalent to the area of the vibrating plate was mounted to it. This reflective plate is composed of a planar reflective plate and a truncated cone-shaped reflective plate. In this study, first, the directional characteristics of a circular transverse vibrating plate-type aerial ultrasonic sound source with an integrated rigid wall structure were examined. Next, the planar reflective plate and truncated cone-shaped reflective plate were analyzed to refine the design. Furthermore, a sound source equipped with these reflective plates was fabricated, and various acoustic characteristics were investigated. As the results, when the input power of the sound source was 30 W, the sound pressure was 293 Pa at the distance of 2 m. This is a unidirectional sound wave with a very intense sound pressure.