Accession Number : AD0284675

Title :   PRELIMINARY MEASUREMENTS OF THE APPARENT NOISE FROM SHIP SUSPENDED HYDROPHONES. PART I: GRENADA TROUGH. PART II: BERMUDA AREA

Corporate Author : COLUMBIA UNIV DOBBS FERRY N Y HUDSON LABS

Personal Author(s) : CLAY,C.S. ; SHERRY,H.B. ; GLASER,G.

Report Date : JUL 1962

Pagination or Media Count : 1

Abstract : The apparent noise observed by hydrophones suspended from an anchored ship was measured in half octave bands from 90 cps to 1000 cps. The hydrophone depths range from 2500 ft to 4000 ft. Qualitative observations indicated that noise less than 10 cps might be due to vibrations caused by eddies shed from the cable in the currents. The tests were made in the eastern Caribbean in about 10,000 ft of water. A second set of similar measurements made in the Bermuda area in about 15,000 ft of water gave about the same or slightly higher apparent noise levels. Some evidence that high level impulses may result from rubbing of the cable against the ship's bottom rather than from jerking of the cable as the ship rolls is presented. Also the data taken in silent and normal operating ship indicate that silent ship operation decreased the noise 3 to 5 db. (Author)

Descriptors :   *HYDROPHONES, *SHIP NOISE, *UNDERWATER SOUND EQUIPMENT, ELECTRIC CABLES, HIGH PASS FILTERS, INTERFERENCE, MEASUREMENT, NOISE, REDUCTION, SIGNAL-TO-NOISE RATIC, TOWED BODIES, TOWING CABLES, VIBRATION

Distribution Statement : APPROVED FOR PUBLIC RELEASE