State Key Lab. of Acoust., Chinese Acad. of Sci., Beijing 100080, People's Republic of China and School of Mech. Eng., Georgia Inst. of Technol., Atlanta, GA 30332
State Key Lab. of Acoust., Chinese Acad. of Sci., Beijing 100080, People's Republic of China
An experiment was conducted in shallow water with strong thermocline, located between the depths from 11 to 15 m. Explosive sources were detonated at 7 and 25 m, with receivers also at 7 and 25 m. Band-limited signals with 1/3 oct bandwidth for different center frequencies and ranges were analyzed. The waveform structures are strongly dependent on source and receiver depths, center frequency, and range. A ray-mode theory including beam displacement was used to calculate the waveform structures and to invert for the bottom-loss versus grazing angle. The calculated waveform structures are consistent with the measured ones well.
Standards Committee S12 on Noise. Working group chairs will report on their progress for the production of noise standards. The interaction with ISO/TC 43/SC1 and ISO/TC 94/SC12 activities will also be discussed, with reference to the international standards under preparation. The Chairs of the respective U.S. Technical Advisory Groups (H. E. von Gierke and E. H. Berger) will report on current activities of these International Technical Subcommittees under ISO. Scope of S12: Standards, specifications and terminology in the field of acoustical noise pertaining to methods of measurement, evaluation and control; including biological safety, tolerance and comfort and physical acoustics as related to environmental and occupational noise.