1pUW7. Pressure effect on absorption coefficients in the deep-sea area.

Session: Monday Afternoon, December 2

Time: 3:16

Abstract:

In order to design deep-sea acoustic devices, it is very important to estimate the sound absorption loss in the deep sea. In general, the Thorp equation [F. H. Fisher and V. P. Simmons, J. Acoust. Soc. Am. 62, 558--564 (1977)] is used in the design of deep-sea acoustic equipment for safety monitoring. However, it is known empirically that the measured absorption losses are less than the losses calculated by the Thorp equation [Tsuchiya et al., presented at the Meeting of the Marine Acoustics Society of Japan (1993), p. 77 (in Japanese)] in the deep-sea area. The sound absorption losses in the deep sea were measured using the deep submergence vehicle ``SHINKAI 6500'' of the Japan Marine Science and Technology Center (JAMSTEC). It is known that there is a discrepancy between the measured absorption loss in a water tank and that in the deep sea. The data are close to those measured in the laboratory by Fisher [F. H. Fisher, J. Acoust. Soc. Am. 38, 805--812 (1965)]. It appears that absorption loss decreases quadratically as a function of depth.