SIMPLE METHODS OF ESTIMATING SOURCE LEVELS AND LOCATIONS OF MARINE ANIMAL SOUNDS

This paper describes three relatively simple methods of estimating sou rce levels of marine animal sounds by estimating the source distance a coustically, using one or two hydrophones. The methods are logisticall y simpler than using arrays of hydrophones of known positions but are accurate over a smaller range of distances. One method makes use of th e differences in the arrival times and levels of the signals received at two hydrophones from the same sound emission. No knowledge of the p ositions of the hydrophones is required, however, if these are known t he position of the source can be determined, with left-right ambiguity . The second method uses the difference in received levels only, but r equires the hydrophone spacing to be known. Adequate accuracy requires the source to be significantly closer to one hydrophone than to the o ther. Third, if the direct and surface reflected arrivals can be separ ated, the source level can be determined with a single hydrophone. The methods require accurately calibrated hydrophones. (C) 1998 Acoustica l Society of America. [S0001-4966(98)03509-7]