Directional Sound Through Nonlinear Acoustics
This presentation covers the theory and practice of parametric acoustic arrays. Due to nonlinear interaction in air, an amplitude-modulated ultrasonic beam (around 40 kHz) demodulates itself into audible sound. The acoustic field behaves as a virtual source array with a very narrow beam. Using the Westervelt and Berktay models, the author explains the physical properties, including the +12 dB/octave high-pass response and harmonic distortion. The author also highlights challenges such as transducer bandwidth, low energy efficiency, and shock wave formation.
Citation for the publication
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Author: Dr. Anne de Jong (ASCEE)
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Event: NAG Audio Theme Day (Dutch Acoustical Society)
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Date: September 19, 2022
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Subject: Parametric acoustic arrays, Berktay demodulation, and nonlinear wave propagation
