A non-paraxial model for the audio sound behind a non-baffled parametric array loudspeaker

Area of Science:

• Acoustics
• Acoustic Metamaterials
• Signal Processing

Background:

• Parametric array loudspeakers generate narrow sound beams through nonlinear interaction of high-frequency sound.
• Existing acoustic models often fail to predict audible sound emissions from the back of finite-sized parametric sources in free fields.

Purpose of the Study:

• To develop and validate a non-paraxial acoustic model for finite-sized, disk-shaped parametric sources.
• To investigate the underlying mechanism of audible sound generation on the back side of parametric arrays.

Main Methods:

• Development of a novel non-paraxial model incorporating quasilinear approximation and disk scattering theory.
• Numerical calculation of acoustic fields on both front and back sides of the parametric source.
• Comparison of simulation results with an existing non-paraxial model for a parametric source in an infinite baffle.
• Experimental validation of the model's predictions.

Main Results:

• The developed non-paraxial model accurately predicts the presence of audible sound on the back side of the parametric array.
• Both numerical simulations and experimental results confirm the existence of back-side audible sound.
• The study provides insights into the physical mechanisms responsible for this acoustic phenomenon.

Conclusions:

• The novel non-paraxial model offers a more comprehensive understanding of parametric array acoustics, particularly for finite-sized sources.
• Audible sound emission from the back of parametric arrays is a real phenomenon that requires advanced modeling techniques.
• Further research into the explored mechanism can lead to improved parametric array designs and applications.