Seabed Properties from Acoustic Reflection Measurement: An experiment in the Mediterranean

date January 25, 2013
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Friday, January 25, 2013 4:00 p.m. in ETC 4.150

Nicholas P. Chotiros and Marcia J. Isakson
Applied Research Laboratories
The University of Texas at Austin

The seabed is often modeled as a fluid, visco-elastic solid, or water-saturated poro-elastic material. Using experimental measurements from a sandy seabed, it is shown that the poro-elastic model can fit the measured reflection data better than the other models. Roughness scattering had a significant effect on the measurements requiring a more sophisticated roughness model than Eckart scattering. Reflection loss and roughness measurements were taken at the Experimental Validation of Acoustic Models experiment in 2006 (EVA-06), off the Isola d’Elba, Italy, in collaboration with the NATO Undersea Research Centre. The magnitude and phase of the reflection loss were measured at frequencies from 5 to 80 kHz and grazing angles from 7 to 77 degrees. Approximately 1500 samples were taken at each angle. The roughness was measured with a laser profiler. The measurements were compared with model predictions. The material is based on [M. J. Isakson, N. P. Chotiros, R. A. Yarbrough, and J. N. Piper, “Quantifying the effects of roughness scattering on reflection loss measurements,” J. Acoust. Soc. Am., Vol. 132, pp.  3687-3697, 2012].