The Effect of Attenuation from Fish on Passive Detection of Sound Sources in Ocean Waveguide Environments

Attenuation from fish can reduce the intensity of acoustic signals and significantly decrease detection range for long-range passive sensing manmade vehicles, geophysical phenomena, vocalizing marine life. The effect attenuation herring shoals on Passive Ocean Acoustic Waveguide Remote Sensing (POAWRS) surface vessels is investigated here, where concurrent wide-area active (OAWRS) used to confirm that occluding propagation path are responsible measured reductions in ship radiated sound corresponding losses. Reductions ship-radiated predicted using a formulation through inhomogeneities an ocean waveguide has been previously shown be consistent with experimental measurements OAWRS transmissions. predictions agreement attenuation, position, size, population density groups characterized imagery as well situ echosounder specific path. Experimental presented here previous theoretical common heuristic formulations employing free space scattering assumptions significant error. theory found necessary accurate predictions.