停泊中の船舶から海中へ放射される雑音の干渉効果 [in Japanese] Interference of Underwater Noise Emitted by Drifting Vessel [in Japanese]
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Transmission ray of underwater noise emitted by drifting vessel have two direction i.e. direct and reflected rays. Interference occurs to receive the mixed sound wave from both rays at a hydrophone. The present research compares a theoretical interference with the basis of actual measurements of interference.<br>We observed vertically underwater noise emitted by drifting vessel with intervals one meter on 26m depth and 93m depth sea area. Also spectrogram by spectrum data was made in each depth. The results, at both stations the same striped patterns appeared on a range of about 13m and 16m from sea bottom, and on the frequency range of over 50Hz. By theoretical pattern, this spectrum level changed with their phase differences, and the interference relate to the depth of a hydrophone from the sea bottom rather than the depth of sea area. If the frequency increased, the term pattern decreases. That observed patterns coincided with a theoretical interference patterns by both waves at the frequency range of over 100Hz. A great term pattern appeared at the shallow sea area rather than the deep sea.
NSUGAF 63(2), 213-221, 1997-03-15
The Japanese Society of Fisheries Science