Modelling sound propagation in the ocean from multiple sound sources

Abstract

Modelling sound propagation in ocean waveguides normally assumes that a sound source can be represented by a single, idealised, point source. However, the ocean environment contains many different and complex sound sources and it may not always be appropriate to represent these as a point source, especially in the acoustic near field and/or shallow water environments. Accordingly, sound propagation in an ocean waveguide is examined here using a numerical model to accommodate multiple point and dipole sources that are arranged vertically in the ocean. Predictions are obtained using a semi analytic finite element approach, which is a normal mode model that computes eigenmodes propagating in the range direction. This enables the addition of multiple point sources, as well as depth dependent fluid properties, and compressional and shear waves in the seabed. An investigation is then undertaken to ascertain where the acoustic near field ends for complex sources in order to examine the appropriateness of the assumption of an idealised point source for these more complex problems.