Godin O. A. (April 2008): Low-frequency sound transmission through a gas-liquid interface. J. Acoust. Soc. Am., 123 (4), 1866-1879. doi:10.1121/1.2874631Full text not available from this repository.
Typically, sound speed in gases is smaller and mass density is much smaller than in liquids, resulting in a very strong acoustic impedance contrast at a gas–liquid interface. Sound transmission through a boundary with a strong impedance contrast is normally very weak. This paper studies the power output of localized sound sources and acoustic power fluxes through a plane gas–liquid interface in a layered medium. It is shown that, for low-frequency sound, a phenomenon of anomalous transparency can occur where most of the acoustic power generated by a source in a liquid half-space can be radiated into a gas half-space. The main physical mechanism responsible for anomalous transparency is found to be an acoustic power transfer by inhomogeneous (evanescent) waves in the plane-wave decomposition of the acoustic field in the liquid. The effects of a liquid’s stratification and of guided sound propagation in the liquid on the anomalous transparency of the gas–liquid interface are considered. Geophysical and biological implications of anomalous transparency of water–air interface to infrasound are indicated.
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