The effects of ocean surface roughness on the transmission of sound from an airborne source
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Authors
Helbig, Raymond Allan
Subjects
Sound transmission
Ocean surface roughness
Air-sea interface
Underwater sound
Helicopter sound field
Transmission loss
Ocean surface roughness
Air-sea interface
Underwater sound
Helicopter sound field
Transmission loss
Advisors
Medwin, Herman
Date of Issue
1970-12
Date
December 1970
Publisher
Monterey, California, Naval Postgraduate School
Language
en_US
Abstract
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.
Type
Thesis
Description
Series/Report No
Department
Committee for Engineering Acoustics
Organization
Identifiers
NPS Report Number
Sponsors
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Distribution Statement
Approved for public release; distribution is unlimited.
Rights
This publication is a work of the U.S. Government as defined in Title 17, United States Code, Section 101. Copyright protection is not available for this work in the United States.