실험실 조건하에서 측정된 순수 딱총새우 잡음의 음향학적 특성

Abstract

The ambient noise in the ocean shows very different dependence on marine life as well as wind, rainfall, snow, hailstorm and shipping. The sources of ambient noise in the deep ocean are made clearly from the summary of a large amount of data measured in the 1940s. According to this summary the main sources of ambient noise were distant shipping and ocean surface wind. The ambient noise in the coastal sea is more complicated than the noise in the deep ocean due to the breaking wave and the marine life as well as the shipping and the wind. Since the biological noise due to the marine life has very high diurnal dependence and seasonal variation, it can greatly affect on a change of ambient noise than the others. Especially it is well known that the noises of dolphin and snapping shrimp affect on a sonar ping signal. In the coastal sea where the snapping shrimp lives, its noise always exists with ambient noise such as the shipping noise and the wind noise. Therefore the snapping shrimp noise can more influence on the ambient noise and the sonar detection performance than the dolphin noise. Because of this reason many researchers measured and analyzed the snapping shrimp noise. In this study, we analyzed typical temporal waveforms and frequency spectra for four species of snapping shrimp under laboratory conditions. Individual noise waveforms appeared similar shape each other. However, their frequency spectra were differently appeared on the duration time for compression of the cavitation bubble.