title: Low-frequency sound transmission through a gas-liquid interface.
abstract: 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.
authors.affiliation: CIRES, University of Colorado and NOAA/Earth System Research Laboratory, Boulder, Colorado 80305, USA. oleg.godin@noaa.gov
authors.forename: Oleg A
authors.initials: OA
authors.lastname: Godin
mesh_terms: D004777:Environment; D005740:Gases; D013016:Sound
chemical_list: D005740:Gases