Accession Number : AD0287056

Title :   STUDY OF UNDERWATER ACOUSTIC ABSORBERS

Corporate Author : GENERAL DYNAMICS/POMONA CALIF

Personal Author(s) : RUBEGA,R.A. ; PRASSE,E.I.

Report Date : 15 MAR 1962

Pagination or Media Count : 1

Abstract : A theoretical and experimental study of possible new methods of underwater sound absorption in the frequency range from 2 to 10 kc was made. Four methods of determining sound absorption were considered: (1) measurment of the flexural vibration of damped plates under excitation by an incident sound wave; (2) measurement of decay time in a small-scale reverberation tank; (3) measurement of direct echo reduction in a fullscale sonar tank; and (4) energy accounting techniques, both in air and under water. With Method (1), it was found that no direct indication of flexural motion could be observed for the plates tested with the pickup and instrumentation used. Under Method (2), qualitative comparisons of various absorbing materials are presented. Under Method (3), results were obtained for a forest type of absorber system consisting of neoprene strips; while under Method (4), results are given for one type of absorbing plate. Limitations and possible sources of error for all methods are discussed. (Author)

Descriptors :   *ACOUSTIC FILTERS, *UNDERWATER SOUND, ABSORPTION, ALUMINUM, DAMPING, HYDROPHONES, LAMINATES, METAL PLATES, PLASTICS, REFLECTION, RUBBER, SOUND, SOUND TRANSMISSION, STEEL, TEST METHODS, VIBRATION, VIBRATION ISOLATERS

Distribution Statement : APPROVED FOR PUBLIC RELEASE