Design of a constant beamwidth beamformer for the length-limited parametric array loudspeaker

Liang, Jiangnan, Gou, Jiacheng, Bai, Ruyu and Shi, Chuang (2020) Design of a constant beamwidth beamformer for the length-limited parametric array loudspeaker. In InterNoise 2020: INTER-NOISE and NOISE-CON Congress and Conference Proceedings. vol. 2990-3981, Institute of Noise Control Engineering of the USA. pp. 3658-3664 .

Record type: Conference or Workshop Item (Paper)

Abstract

The length-limited parameter array loudspeaker (LLPAL) consists of two parametric array loudspeakers (PALs) with separate carrier frequencies. Each of the PALs can be used alone as a directional sound source that produces the difference frequency from the ultrasonic carrier and sideband frequencies by the nonlinearity of air. The beam length of the PAL depends on the carrier frequency. Therefore, in the LLPAL, two sound beams interference with each other, resulting in a length-limited beam. This paper first modifies the far-field Westervelt's directivity and establishes the directivity model of the LLPAL. Subsequently, a beamformer design method is presented for the LLPAL to achieve a constant beamwidth across a wide band of the difference frequency at a given distance of observation.

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