Frequency-Time Correlation of Surface Scattered Underwater Sound.

Abstract

The wind driven surface of a large anechoic tank was used to study forward scattered underwater sound. A 10 kHz sawtooth signal was used to drive an omnidirectional source to insonify the rough surface. Direct and reflected path sound signals to a point hydrophone were separated by appropriate gating and the reflected path signal was analyzed for up to 2 minutes at 10 and 20 msec. intervals, using digital FFT spectral analysis. Graphs of sound pressure level vs. time for every 10 kHz from 30 kHz to 120 kHz (Surface roughnesses between 1.1 and 10.5) are shown. Correlation of the scattered sound pressure with frequency was analyzed. Evidence is presented to support the hypothesis that for large roughnesses, the instantaneous sound amplitudes are harmonic functions of sound frequency; that is, there is a consistent frequency separation between instantaneous amplitude maxima at one frequency and minima at another frequency. (Author)

Open PDF

Document Details

Document Type
Technical Report
Publication Date
Dec 01, 1976
Accession Number
ADA039374

Entities

People

  • Michael Francis Loomis

Organizations

  • Naval Postgraduate School

Tags

Communities of Interest

  • Energy and Power Technologies
  • Materials and Manufacturing Processes

DTIC Thesaurus Topics

  • Acoustic Signals
  • Acoustic Waves
  • Amplitude
  • Computer Programs
  • Computers
  • Converters
  • Data Acquisition
  • Data Processing
  • Digital Computers
  • Frequency
  • Measurement
  • Research Facilities
  • Sound Pressure
  • Sound Waves
  • Surface Roughness
  • Underwater Sound
  • Waves

Readers

  • Acoustical Oceanography.
  • Atmospheric Science / Meteorology, specifically Wind Wave Turbulence.