抄録
The frequency analysises of the sea noise and sound of fishes are very important to discriminate the species of fish or to forecast the catch of fish in set net fishing. We recorded on the magnetic tape recorder the sounds of yellowtail, squid and porpoise which were received by hydrophone devices or sonobuoy devices. And then, these sounds were analyzed for frequency by means of the Panoramic Sonic Analyzer. We obtained the following conclusions. 1) When the sea was calm, it was indicated that the level of sea noise was higher in the frequency range below 1 kilocycle the upper range. (Fig. 6A, B, C) 2) When the sea was rough, the level of sea noise increased in the whole frequency band and it depended upon the velocity of wind, but we found no change in the frequency distribution. (Fig. 6D) 3) The yellowtail and the squid made some peculiar swimming sound which distributed in the frequency band higher than the sea noise and therefore, we could clearly discriminate the sea noise and the sound of fishes. (Fig. 6E, F)
