Development of a Directional Loudspeaker System for Sound Reproduction

We have developed a directional audible sound reproduction system using ultrasonic transducers. This novel directional audio is a result of the nonlinear propagation and subsequent self-demodulation of high-intensity amplitude modulated (AM) ultrasonic waves. In this paper, the propagation characteristic of the directional sound generated by parametric acoustic arrays is investigated using numerical algorithm in the time-domain and three preprocessing methods are employed to reduce the distortions of audio beams. Based on the theoretical analysis and computation simulations, a directional loudspeaker has been designed and prototyped. Furthermore, two directional loudspeakers are applied to the sound reproduction in a target zone. The scattering of sound by sound is implemented in the vicinity of interaction region of two sound beams and verified by the experiments carried out in an anechoic chamber.