Accession Number : AD0782271

Title :   Project Hiawatha Long-Range Shallow-Water Sound Propagation in Lake Superior.

Descriptive Note : Technical memo.,


Personal Author(s) : Browning,D. G. ; Thorp,W. H. ; Friedel,F. C. ; LaPlante,R. F.

Report Date : 20 JUN 1968

Pagination or Media Count : 11

Abstract : Sound-propagation measurements were made along a 100-mile path in Lake Superior during September 1967 in an area in which water depth exceeded 600 ft. One-half pound TNT charges were detonated at the axis of a sound channel and received on a hydrophone suspended at the same depth. Acoustic reception by totally refracted paths was analyzed in 10 frequency bands between 500 and 8900Hz. The increase in propagation loss with range was found to be greater below 2kHz than commonly observed in ocean sound channels and larger throughout the range of frequencies than theory would predict for an isotropic, freshwater medium. It is proposed that the largely unexpected results arise from local changes in the temperature structure within the first 150 feet of water depth. (Modified author abstract)

Descriptors :   *Underwater sound, *Great Lakes, Shallow water, Hydrophones, Low frequency, Attenuation, Explosive charges, Underwater sound signals, Fresh water, Measurement

Subject Categories : Acoustic Detection and Detectors

Distribution Statement : APPROVED FOR PUBLIC RELEASE