Title: Sediment critical angle estimation via <i>in situ</i> acoustic measurements
Abstract: The basic physics of sound penetration into ocean sediments is a current area of active research since a good understanding of this phenomenon is essential for designing sonar systems that can detect, localize, classify, and identify buried objects. The sound speed of the sediment is a crucial parameter since the ratio of sound speeds at the water–sediment interface determines the critical angle. Sediment sound speed is typically measured with core samples using high-frequency (100’s of kHz) pulsed travel time measurements. Simulations using Biot theory and taking into account sediment permeability have shown that there may be a significant frequency dependence to sediment sound speed in the range 1–100 kHz. Here, sediment sound speed and critical angle estimation are investigated through the analysis of in situ acoustic measurements. Acoustic energy in the frequency range 2–16 kHz was directed toward a sandy seabottom, and a buried 14-element hydrophone array measured the incoming signals. The critical angle is estimated by analyzing both the variations of the penetration ratios and signal arrival times versus frequency, burial depth, and grazing angle. The influence of bottom roughness and sonar beamwidth on the penetration ratio is also investigated.
Publication Year: 1999
Publication Date: 1999-02-01
Language: en
Type: article
Indexed In: ['crossref']
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