Convergence of Sound Waves Radiated from Aerial Ultrasonic Source Using Square Transverse Vibrating Plate with Several Reflective Boards

Abstract

An ultrasonic source using a metal square vibrating plate radiates extremely intense ultrasonic waves into the air. The plate experiences transverse vibration when a longitudinal vibration is applied to the central point of the plate. In the lattice mode, the nodal positions of the plate take the form of straight lines, creating a lattice-like pattern. The source radiates four directional sound waves in the far field. The aim of our study is to obtain high sound pressure by converging the sound waves radiating from a source of this shape in the near field. We studied the construction of an ultrasonic field converged by using several flat boards plus four parabolic reflective boards placed near the source. The results of the measurements of sound pressure and phase distributions show that these boards can create the convergence of sound waves.