Scattering by a rigid sphere of audio sound generated by a parametric array loudspeaker

Abstract

This work investigates the scattering by a rigid sphere of audio sound generated by a parametric array loudspeaker (pal). A computationally efficient method utilizing a spherical harmonic expansion is developed to calculate the quasilinear solution of audio sound fields based on both Kuznetsov and Westervelt equations. The accuracy of using the Westervelt equation is examined, and the rigid sphere scattering effects are simulated with the proposed method. It is found the results obtained using the Westervelt equation are inaccurate near the sphere at low frequencies. Contrary to conventional loudspeakers, the directivity of the audio sound generated by a pal severely deteriorates behind a sphere, as the ultrasounds maintaining the directivity of the audio sound are almost completely blocked by the sphere. Instead, the ultrasounds are reflected and generate audio sound on the front side of the sphere. It means that a listener in front of the pal will hear the audio sound scattered back after introducing the sphere as if it is reflected by the sphere. The experiment results are also presented to validate the numerical results.

On the scattering of a disk source by a rigid sphere for directivity broadening

“…Previous studies of spheres have been primarily focused on the scattering of the sound from a point source, rather than from a speaker diaphragm, for gaining insight into the head related transfer function (HRTF), either in the presence of a reflecting surface 11 or not, 12 or for the study of scattering in general. 13 One of the reviews of this paper drew the attention of its authors to a paper by Zhong et al, 14 which was published shortly after this one was submitted. Although Fig.…”