Comparison of Propagation Models for the Characterization of Sound Pressure Fields

This paper aimed at comparing different propagation models for the calculation of sound pressure fields in the ocean as well as sound exposure levels. The chosen models are freely available and commonly used by the general underwater acoustics community when sound propagation losses need to be predicted in an ocean environment. The models used were Ocean Acoustics and Seismic Exploration Synthesis (OASES), RAM, Bellhop, and Kraken, which are all based on different approximations of the wave equation. The comparison exercise was carried out by calculating propagation loss, sound pressure waveforms, and sound exposure levels produced by a modeled air gun source. Calculations were performed for a simple range-independent problem of a Pekeris waveguide and produced insights into applicability of each model with regards to near- and far-fields, as well as low and high frequencies for example. Two of the models, RAM and Bellhop, which are suitable to range-dependent problems, were also used to solve a slightly complex case having a sloping bottom. It is hoped that the results presented here will be particularly useful to those who need to use propagation models for marine environmental and bioacoustics studies.