A PORTABLE, GENERAL-PURPOSE UNDERWATER SOUND MEASURING SYSTEM.

Abstract : A portable underwater sound-pressure measuring system was developed and tested. The system was shown to be capable of measuring very low ambient-noise levels. High self-noise levels at frequencies less than 50 to 63 Hz are likely to be present if measurements are made from a drifting ship, and the cable is towed at drift velocity, probably because of a combination of flow noise and noise arising from cable vibrations. These high self-noise levels can be satisfactorily eliminated by using a slack cable system as described in the report. (Author)