Accession Number : AD0621161

Title :   SOUND-WAVE FLUCTUATIONS IN AN ENVIRONMENT OF SIMULATED RANDOM INHOMOGENEITY,

Corporate Author : LOCKHEED MISSILES AND SPACE CO PALO ALTO CALIF LOCKHEED PALO ALTO RESEARCH LAB

Personal Author(s) : Knollman,G. C. ; Hartog,J. J.

Report Date : 29 MAR 1965

Pagination or Media Count : 6

Abstract : A research program has been conducted under controlled laboratory conditions of acoustic amplitude fluctuations arising during sound transmission through an underwater medium containing a spatially random distribution of inhomogeneities that are temporally stationary. Spherical, thin-walled, liquid-filled balloons of a diameter large in comparison with the acoustic wavelength were situated at random in a large underwater facility. Refractive indices of the fluid spheres were varied up to 1% from the index for water. Thus, numerous weak, large-scale refractiveindex variations were introduced in an experimental acoustic chamber under controlled temperature conditions. Signal fluctuations were measured in plane-wave sound transmission through the simulated random environment for four different ultrasonic frequencies and four transmitter-to-receiver ranges. Multiudinous ensembles were realized at each frequency and range by rotation of transmitter-receiver line of sight about its midpoint. The experimental arrangement and measurement procedures are detailed herein, and mean-square amplitude fluctuations that were determined are presented as a function of both acoustic frequency and transmitter-to-receiver range. Theoretical results for plane-wave propagation in a statistically isotropic medium are included as a foundation for the laboratory findings. (Author)

Descriptors :   (*SOUND TRANSMISSION, UNDERWATER SOUND), (*UNDERWATER SOUND, SOUND TRANSMISSION), (*ACOUSTICS, UNDERWATER SOUND), MECHANICAL WAVES, PROPAGATION, ULTRASONIC RADIATION, SPHERES, REFRACTIVE INDEX

Distribution Statement : APPROVED FOR PUBLIC RELEASE