The effects of ocean surface roughness on the transmission of sound from an airborne source
Helbig, Raymond Allan
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Using the research platform "FLIP", experiments were conducted to determine the effect of measured ocean surface roughness on transmission of sound from an airborne source into the sea. Signal noise both at the air-water interface and at points in the underwater sound field were recorded using modified AN/SSQ-57 sonobuoys. Ocean wave spectra and rms wave height, o, were determined from simultaneous recordings of ocean surface wave height variations. The results of analog data analysis compared well with theory developed by Hagy and Medwin: for R < T, perpendicular incidence transmission loss increased approximately as 10 log 10er where R = k22o2 (c2/c1 - cos e2)2. (Subscript 2 refers to propagation constant, speed , and angle of transmission in water; subscript l in air). For l < R < 4 the transmission loss decreased with increasing roughness, presumably due to off-axis incoherent contributions. 2 2 )2 10 log1 0 eR where R = k2 o (c2;c1 cos e1 - cos e 2 • (Subscri pt 2 refers to propagati on constant, speed , and angl e of transmi ssion i n water; subscri pt l i n ai r). For l < R < 4 the transmi ssion loss decreased wi th i ncreasi ng roughness, pre5umabl y due to off-axis incoherent contri buti ons.
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Hagy, James Dixon, Jr. (Monterey, California; Naval Postgraduate School, 1970-09);The Helmholtz integral and the Kirchhoff approximation have been used to develop predictions for the transmission of sound through a rough air-sea interface. A model study was conducted with wind-driven surfaces generated ...
Helbig, R. A.; Medwin, Herman (Monterey, California. Naval Postgraduate School, 1972-05-15); NPS-61Md72051AThe predicted dependence of sound transmission on the statistics of the randomly-rough interface between dissimilar fluids has been studied by use of the Helmholtz Integral. The predictions have been verified for radiation ...
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