Inverting for sandy sediment sound speed in very shallow water using boat noise

Abstract

Small boat propeller noise was recorded on a single hydrophone in very shallow water for the purpose of estimating sediment sound speed. The experiment was conducted near shore in water depth between 2 and 10 m. The sediment consisted of uniform sand. The lone hydrophone was moored 2 m above the bottom at 6 m depth. A small boat traveling at constant speed was used as the sound source, and ran both parallel and perpendicular to shore. Thus, both the range independent waveguide case and wedge shaped waveguide case could be investigated. The source tracks were recorded by using a GPS recorder on the boat. Water depth in the entire area was measured, as was the sound speed profile at the receiver. The processed date sets resulted in interference patterns in range-frequency plots. Aided by numerical simulations, sediment sound speed can be estimated over the frequency range of 500–4500 Hz. [Work supported by the U.S. Office of Naval Research.]