Design of a constant beamwidth beamformer for the parametric array loudspeaker

Shi, Chuang and Bai, Ruyu (2019) Design of a constant beamwidth beamformer for the parametric array loudspeaker. Ochmann, Martin, Vorländer, Michael and Fels, Janina (eds.) In Proceedings of the 23rd International Congress on Acoustics : Integrating 4th EAA Euroregio 2019 : 9-13 September 2019 In Aachen, Germany. RWTH Publications. pp. 3077-3081 . (doi:10.18154/RWTH-CONV-239086).

Record type: Conference or Workshop Item (Paper)

Abstract

The parametric array loudspeaker (PAL) is an unconventional type of directional sound source that transmits inaudible ultrasonic frequencies in air to generate the audible difference frequency based on the parametric array effect. The convolution model describes the beampattern of the PAL by convolving the product beampattern with the Westervelt beampattern. As a result, the beamwidth of the PAL becomes narrower when the difference frequency increases. A change of timbre is therefore perceived when people stand at an off-axis angle of the PAL. Hence, a constant beamwidth beamformer is required. This paper works on the beamformer design to result in the product beampattern that becomes broader when the difference frequency increases, in
order for the Westervelt beampattern to be compensated. A constant half-power-beamwidth (HPBW) is successfully achieved for the typical frequency range of the PAL.

Text

769497 - Version of Record

Available under License Creative Commons Attribution Non-commercial Share Alike.

Download (805kB)