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Scattering by a rigid sphere of audio sound generated by a parametric array loudspeaker
Jiaxin Zhong1, Ray Kirby1, Mahmoud Karimi1
1Centre for Audio, Acoustics and Vibration, University of Technology Sydney, New South Wales 2007, Australia.
The Journal of the Acoustical Society of America
|April 2, 2022
Summary
This study shows that parametric array loudspeakers (PALs) scatter audio sound differently around spheres. Unlike regular speakers, PALs’ sound directivity is disrupted, with sound reflecting forward from the sphere.
Area of Science:
- Acoustics
- Nonlinear Acoustics
- Computational Acoustics
Background:
- Parametric array loudspeakers (PALs) generate audio sound from ultrasound.
- Scattering of sound by objects is crucial for understanding sound propagation.
- Previous studies have not fully explored PAL sound scattering by rigid spheres.
Purpose of the Study:
- To investigate the scattering of audio sound generated by a PAL when interacting with a rigid sphere.
- To develop and validate a computationally efficient method for simulating this phenomenon.
- To compare the accuracy of the Kuznetsov and Westervelt equations for this specific application.
Main Methods:
- Development of a computationally efficient method using spherical harmonic expansion.
- Calculation of the quasilinear solution for audio sound fields based on Kuznetsov and Westervelt equations.
- Simulation of rigid sphere scattering effects for audio sound generated by a PAL.
Main Results:
- The Westervelt equation shows inaccuracies in predicting sound fields near the sphere at low frequencies.
- The directivity of PAL-generated audio sound significantly deteriorates behind the sphere.
- Ultrasound is blocked by the sphere, leading to audio sound generation on the front side via reflection.
Conclusions:
- The proposed method accurately simulates the scattering of audio sound from a PAL by a rigid sphere.
- The Westervelt equation is less accurate than the Kuznetsov equation for low-frequency scattering near the sphere.
- PALs exhibit unique scattering characteristics compared to conventional loudspeakers, with sound reflecting forward from an object.
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