Title: RAPID ENVIRONMENTAL ASSESSMENT WITH AMBIENT NOISE
Abstract: At frequencies below 5 kHz, shallow rays from distant sources create a strong, nearsymmetrical horizontal lobe in the vertical directional density function of ambient noise in shallow water. The angular half-width of the lobe is equal to the critical grazing angle, αc, of the seabed. From a two-hydrophone measurement of the vertical coherence of the noise, the critical angle may be estimated, from which the sound speed in the sediment may be determined. Once the sediment sound speed is known, the remaining geo-acoustic parameters may be obtained from the dispersion relations predicted by a recently developed theory of wave propagation in saturated granular media. The combination of the noise measurement and the new theory provides a basis for performing rapid, cost-effective geo-acoustic surveys of shallow water sediments using more or less conventional sonobuoy technology.
Publication Year: 2004
Publication Date: 2004-01-01
Language: en
Type: article
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Cited By Count: 3
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