Parametric Acoustic Waves and Sound Field Manipulation

Parametric acoustic waves exploit the nonlinear interaction of high-frequency ultrasonic beams in a medium to produce low-frequency sound with exceptionally narrow beamwidths. By transmitting two closely spaced ultrasonic carriers, the medium itself acts as a demodulator, generating a difference-frequency wave that inherits the directivity of the ultrasonic sources. This approach enables compact transducer designs to project highly focused audible beams without the need for large apertures. Sound field manipulation encompasses techniques such as beam steering, shaping of acoustic intensity distributions, and control of sidelobe structure, achieved through phased arrays, transducer geometry, signal pre-processing and adaptive algorithms. Applications span underwater communication and sub-bottom profiling, targeted audio delivery in public spaces and virtual reality, non-invasive medical ultrasound, and precision non-destructive testing. Recent advances in numerical modelling, optical measurement and signal processing have refined the prediction and control of parametric fields in complex environments, including shallow-water waveguides and atmospheric propagation over large distances. The global significance of this research lies in its ability to deliver energy-efficient, spatially selective sound with minimal interference, opening new horizons in acoustical engineering and applied physics.

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Parametric Acoustic Waves and Sound Field Manipulation publication trend

The graph below shows the total number of articles in parametric acoustic waves and sound field manipulation across all publications each year (not limited to Nature Index journals).

Technical terms

Parametric Acoustic Array (PAA): A compact transducer system that uses ultrasonic carriers and medium nonlinearity to generate a highly directional audible beam.

Self-demodulation: The nonlinear process by which the propagation medium converts ultrasonic carrier waves into a lower-frequency difference component.

Difference-frequency wave: The audible sound component resulting from the interaction of two ultrasonic beams at close but distinct frequencies.

Directivity: The degree to which an acoustic source concentrates energy in a specific direction, often quantified by beamwidth and sidelobe levels.

Nonlinear propagation: Wave transmission in which amplitude affects wave speed and interactions, leading to generation of harmonics and difference frequencies.

References

1. Dispersion Influence of Electroacoustic Transducer Parameters in the Design Process of Miniature Loudspeaker Arrays and Omnidirectional Sound Sources. Sensors (2024).
2. Parametric Acoustic Array and Its Application in Underwater Acoustic Engineering. Sensors (2020).
3. Experimental Study of a Broadband Parametric Acoustic Array for Sub‐Bottom Profiling in Shallow Water. Shock and Vibration (2018).
4. Signal Processing for Parametric Acoustic Sources Applied to Underwater Communication †. Sensors (2020).
5. Frequency shift of parametric sound by face-to-face pair of sources in relative motion. The Journal of the Acoustical Society of America (2024).
6. Spurious-sound-free measurement of parametric acoustic array using optical interferometry. JASA Express Letters (2021).
7. Study on Sound Field Properties of Parametric Array Under the Influence of Underwater Waveguide Interface Scattering Based on Non-Paraxial Model—Theory and Experiment. Journal of Marine Science and Engineering (2025).
8. High-Directional Sound Propagation Over the Earth’s Surface. Archives of Acoustics (2020).
9. Visualization of Demodulated Sound Based on Sequential Acoustic Ray Tracing with Self-Demodulation in Parametric Array Loudspeakers. Applied Sciences (2024).