Accession Number : AD0700245

Title :   ACOUSTICAL AND BIOLOGICAL RESULTS OF SAMPLING IN THE DEEP SCATTERING LAYERS.

Descriptive Note : Research rept.,

Corporate Author : NAVY UNDERWATER SOUND LAB NEW LONDON CONN

Personal Author(s) : Brown,Charles L. , Jr. ; Fessenden,Frederick P.

Report Date : 03 OCT 1969

Pagination or Media Count : 33

Abstract : Deep scattering layers (DSL) present formidable interference to underwater acoustic systems in large areas of the Atlantic and Pacific Ocean. This interference is due to volume reverberation from the DSL and appears to be caused primarily by the backscattering of sound from fish possessing gas-filled swim-bladders. From a deep research vehicle, samples of organisms were taken successively below, in, and above the DSL in an area of the western North Atlantic during August 1966. Mere numbers of fish did not appear significant in determining the acoustic properties of the DSL. From results of the biological sampling, scattering strengths have been calculated for single frequencies of 4 kHz and 12 kHz, as well as for several frequency bands. The results near 12 kHz agree reasonably well with experimental values for similar areas, but results near 4 kHz are somewhat lower than those of other investigations. (Author)

Descriptors :   (*UNDERWATER SOUND, INTERFERENCE), (*AQUATIC ANIMALS, UNDERWATER SOUND), SOUND TRANSMISSION, REVERBERATION, BACKSCATTERING, DEEP WATER, COLLECTING METHODS

Subject Categories : Biology
      Acoustics

Distribution Statement : APPROVED FOR PUBLIC RELEASE