Low Frequency Ocean Ambient Noise: Measurements and Theory,
NAVAL UNDERWATER SYSTEMS CENTER NEW LONDON CT NEW LONDON LAB
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Low frequency ocean ambient noise data are reviewed and summarized. The experimental data, both omnidirectional and directional, when not dominated by shipping noise, are shown to suggest wind dependent noise at the low frequencies 500 Hz. Candidate mechanisms are examined with the result that wave-turbulence interaction at low sea states and collective bubble oscillations at high sea states are identified as possible sources of this sound. A description of the sonic properties of bubbly water is presented for low void fractions consistent with those observed in bubble clouds and plumes produced by breaking waves. A description of the collective bubble water mixture as the resonant oscillation of a flexible volume with a sonic speed determined by the properties of the mixture is presented.