3pUW2. Wind-dependent sea noise in open and enclosed waters.

Session: Wednesday Afternoon, December 4

Time: 2:16

Author: Douglas H. Cato
Location: Defence Sci. and Technol. Organisation, Pyrmont, NSW, Australia


Because of low shipping densities and thus low traffic noise in some of the waters around Australia, ambient noise measurements often show evidence of wind dependence at low frequencies. Significant differences, however, have been observed between open oceanic waters and enclosed or partially enclosed waters, in the behavior of noise as a function of wind speed at low frequencies (less than 200 Hz). In enclosed waters, the wind-dependent noise spectrum is similar to that of Wenz [G. M. Wenz, J. Acoust. Soc. Am. 34, 1936--1965 (1962)], having a broad peak at about 500 Hz. In open waters, there is also evidence of a second component that is dominant at low frequencies, significantly exceeding the level of the ``Wenz'' component at these frequencies. This difference has been observed for similar water depths. One difference between the open and enclosed waters is the absence of swell in the enclosed waters, due to the limited wind fetch. The differences in wind-dependent noise may be related to differences in the behavior of wave breaking and bubble clouds as a result of the presence or absence of swell.

ASA 132nd meeting - Hawaii, December 1996