Sound Depth Research Articles

Digital sound velocity calculator

A digital apparatus for determining the velocity of sound at a selected position in a liquid media is provided with a means for representing the conductivity, temperature and depth of the position in the form of digital numbers, and provides a digital calculating means receiving each of the digital numbers for calculating the velocity of sound as a function of conductivity, temperature, and depth. The sound velocity may be calculated at a succession of positions to provide sound velocity versus depth profile of the liquid media.

Surface decoupling effects in ambient noise modeling

Image interference effects near the are known to affect the coupling of energy from shallow sound sources into propagation channels. Since sound sources which contribute most to ambient noise in the ocean are located within the upper 20 m of the water column, surface is an important factor in noise modeling. The presentation deals with the sensitivity of the decoupling effect to frequency, range, sound depth, bottom loss, bottom slope, and water depth and concludes that significant regional changes can result. The implication of geographic changes in ambient noise are modelled by comparing two different noise regimes—one with predominantly close shipping in a bottom limited environment, the other having more distant shipping and a sound speed excess. Changes in received omnidirectional spectra are interpreted in terms at decoupling effects. [Work supported by Office of Naval Research (LRAPP program).]

Barents Sea continental margin sonobuoy data

Results from 68 closely spaced sonobuoys obtained aboard R/V Bartlett are combined with 30 published sonobuoy results obtained aboard R/V Vema to provide about 300 velocity solutions from the Barents Sea area and its western continental margin. Sections have been compiled from the closely spaced Bartlett stations, and statistical regressions of sediment sound velocity versus depth were made with all the available data. It was found that distinct geologic provinces from this region can be characterized with five separate velocity-depth curves, based on the regressions. The very low velocity gradient in the thick Tertiary wedge of sediments just west of the Barents shelf probably indicates rapid, deltaic deposition. More than 9 km of subbottom penetration was achieved in this Tertiary wedge.