Insertion loss of a thin partition for audio sounds generated by a parametric array loudspeaker

Abstract

Unlike the audio sound generated by traditional sources, the directivity of that generated by a parametric array loudspeaker (pal) deteriorates significantly after passing through a thin partition. To study this phenomenon, the pal radiation model based on the Westervelt equation, and the plane wave expansion method are used to calculate the sound fields behind a sheet of aluminum foil and a porous material blanket under the quasi-linear assumption, where the paraxial approximation is assumed only for ultrasonic waves. The audio sounds generated by a point monopole and a traditional directional source are presented for comparison. Both simulation and experiment results show that the transmitted sound from a pal behind the thin partition is small and less focused on the radiation axis because most of the ultrasounds forming the directivity of the pal is blocked by the thin partition which has little effect on the traditional audio sources.