ASA 126th Meeting Denver 1993 October 4-8

4pAB11. Variation in received level from man-made low-frequency underwater noise sources as a function of diving animal depth.

William T. Ellison Karen S. Weixel

Marine Acoust., Inc., 14 Pelham St., Newport, RI 02840

Christopher W. Clark

Cornell Univ., Ithaca, NY 14850

Interest in the effects of low-frequency (<1 kHz man-made noise on marine wildlife highlights the need for accurate knowledge of the spatial distribution of noise levels within a given wildlife habitat. These levels can vary significantly, particularly with respect to depth within the water column. For diving animals, the ability to measure or predict this variation with depth is a necessary factor in assessing the net impact of that noise; i.e., one needs to perform a convolution of diving patterns (depth as a function of time) with the noise pattern as a function of time and depth. Recent advances in range dependent acoustic propagation modeling allow for the ability to predict with some accuracy the transmission loss from a known source of noise as a function of source characteristics (directivity, sound spectrum, location, and depth) to any given location in a hypothetical habitat. Several examples are presented that illustrate how these models might be used to evaluate the net impact of a passing noise source on pelagic whale species. [Work supported by ONR.]