Audible sound (i.e., of low frequency) has weak attenuation (i.e., can propagate over long distances), but is also characterized by rapid divergence (i.e., difficult to be directed in a specific direction).
Ultrasound wave (i.e., of high frequency), on the contrary, can have a pronounced directivity, but tend to rapidly attenuate in the propagation medium.
However, if two high-frequency (HF) intensive waves propagate in the nonlinear medium, their nonlinear interaction takes place and generation of many new waves with different multiple and combinational frequencies occurs. In this case, the generated difference-frequency wave (DFW) is highly directional and is able to propagate along a sufficient distance from the source, whereas the HF waves quickly attenuate in the medium. Thus, inaudible ultrasound can generate, for example, audible sound that is directional and far-propagating.
Therefore, parametric generation of a difference-frequency wave is actively used in various applications:
- medical applications (ultrasound difference-frequency imaging, monitoring and control of the thermal and mechanical effects of powerful focused ultrasound on various tissues inside the human body);
- highly directional signal that propagates over long distances in the hydroacoustic problems (profiling sea-bottom structures and long-range ocean research);
- highly directional audible sound in the air acoustics (contactless audio guides in the libraries and museums, active noise control systems), etc.
It is well known that the efficiency of using parametric transducers increases with the growth of the initial HF pump waves power, as the power of the low-frequency (LF) radiation generated in the medium at the difference frequency also increases.
Therefore, in order to optimize the characteristics of parametric transducers and to perform acoustic characterization of the LF fields they create, it is necessary to develop original numerical algorithms for solving specific practical problems.
LIMU tasks
- Development of original numerical algorithms for solving three-dimensional parametric problems in highly nonlinear regimes
- Investigation of features of parametric DFW generation
- Numerical calculations to define optimal characteristics of parametric sound radiation
- Development of specialized parametric sources for medical and industrial applications
Activity types
- numerical modeling
- transducer design
Contacts
Details
[1] Fully nonlinear three-dimensional modeling of parametric interactions in the field of a dual-frequency acoustic array / A. V. Kvashennikova, P. V. Yuldashev, V. A. Khokhlova, I. B. Esipov // Journal of the Acoustical Society of America. — 2024. — Vol. 155, no. 3. — P. 1682–1693. DOI: 10.1121/10.0025049
[2] Demodulation of pulsed acoustic signals in strongly nonlinear propagation regimes / A. V. Kvashennikova, M. S. Sergeeva, P. V. Yuldashev et al. // Acoustical Physics. — 2024. — Vol. 70, no. 5. — P. 797–807. DOI: 10.1134/s1063771024602279
[3] Quasilinear approximation for modeling difference-frequency acoustic wave in a diffracting pump-wave beam / A. V. Tyurina, P. V. Yuldashev, I. B. Esipov, V. A. Khokhlova // Acoustical Physics. — 2023. — Vol. 69, no. 1. — P. 30–39. DOI: 10.1134/S1063771022700014
[4] Spectral modeling of difference-frequency generation in the case of two-frequency interaction of ultrasound waves / A. V. Tyurina, P. V. Yuldashev, I. B. Esipov, V. A. Khokhlova // Acoustical Physics. — 2022. — Vol. 68, no. 2. — P. 130–137. DOI: 10.1134/s1063771022020105
[6] Numerical models of nonlinear acoustic wave propagation in medical ultrasound problems and certain applications of aeroacoustics and underwater acoustics / P. V. Yuldashev, O. A. Sapozhnikov, M. M. Karzova, S. A. Tsysar, A. V. Kvashennikova, E. O. Konnova, V. A. Khokhlova. // Moscow University Physics Bulletin. — 2025. — V. 80, № 2. — P. 195–225. DOI: 10.3103/s0027134925700316