Accession Number : ADA079954


Title :   Underwater Sound Scattering by Marine Organisms. A Review,


Corporate Author : MATERIALS RESEARCH LABS ASCOT VALE (AUSTRALIA)


Personal Author(s) : Dunstan,Ian C


Full Text : http://www.dtic.mil/dtic/tr/fulltext/u2/a079954.pdf


Report Date : Aug 1979


Pagination or Media Count : 35


Abstract : Scattering of acoustic energy by inhomogeneities within the water column, or volume reverberation, is a major source of interference to underwater sonar systems. As naval defence systems have a high dependence on acoustic detection, knowledge of the factors that affect sonar interference is relevant to defence interests. This report reviews the literature on interference to sonar propagation by marine organisms, with particular emphasis on Australian waters. Acoustic scattering in the ocean generally occurs in discrete layers called Deep Scattering Layers. Theoretical and experimental investigations have shown conclusively that the scattering is caused by marine organisms. Reverberation profiles are dominated by the resonance back-scattering from gas-filled swimbladders of midwater fish, particularly at frequencies between 0.5 and 20 kHz. At higher frequencies, scattering from fish tissue and planktonic organisms becomes significant. Information on the identity and acoustic properties of sound scattering organisms within the Austrailian region is sparse. (Author)


Descriptors :   *ACOUSTIC SCATTERING , *UNDERWATER SOUND , *BIOACOUSTICS , *DEEP SCATTERING LAYERS , PROFILES , VERTICAL ORIENTATION , CORRELATION TECHNIQUES , AUSTRALIA , REVERBERATION , MARINE BIOLOGICAL NOISE , PLANKTON


Subject Categories : Biological Oceanography
      Acoustics


Distribution Statement : APPROVED FOR PUBLIC RELEASE