Acoustic beamforming of a parametric speaker comprising ultrasonic transducers

A directional audible sound can be generated in air by means of the nonlinear interaction between intense amplitude modulated (AM) ultrasonic waves, which attracts much attention in the audio industry. In the case of sound reproduction by a parametric speaker comprising an array of ultrasonic transducers, a novel algorithm with Chebyshev window has been proposed to control the sidelobe level of the beam pattern by utilizing the acoustic nonlinearity and array signal processing technique. Furthermore, the beamforming approach is extended to the design of a broadband beamformer. In this paper, a single sideband modulation (SSB) system is developed for transmitting audio signal due to its efficient use of both power and bandwidth. By adding different weightings to the carrier and sideband frequencies, a constant beamwidth beamforming is achieved and confirmed in the simulation experiments. (c) 2005 Published by Elsevier B.V.