Underwater Sound Propagation Modeling in a Complex Shallow Water Environment

Abstract

Three-dimensional (3D) effects can profoundly influence underwater sound propagation in shallow-water environments, hence, affecting the underwater soundscape. Various geological features and coastal oceanographic processes can cause horizontal reflection, refraction, and diffraction of underwater sound. In this work, the ability of a parabolic equation (PE) model to simulate sound propagation in the extremely complicated shallow water environment of Long Island Sound (United States east coast) is investigated. First, the 2D and 3D versions of the PE model are compared with state-of-the-art normal mode and beam tracing models for two idealized cases representing the local environment in the Sound: (i) a 2D 50-m flat bottom and (ii) a 3D shallow water wedge. After that, the PE model is utilized to model sound propagation in three realistic local scenarios in the Sound. Frequencies of 500 and 1500 Hz are considered in all the simulations. In general, transmission loss (TL) results provided by the PE, normal mode and beam tracing models tend to agree with each other. Differences found emerge with (1) increasing the bathymetry complexity, (2) expanding the propagation range, and (3) approaching the limits of model applicability. The TL results from 3D PE simulations indicate that sound propagating along sand bars can experience significant 3D effects. Indeed, for the complex shallow bathymetry found in some areas of Long Island Sound, it is challenging for the models to track the interference effects in the sound pattern. Results emphasize that when choosing an underwater sound propagation model for practical applications in a complex shallow-water environment, a compromise will be made between the numerical model accuracy, computational time, and validity.

Assessing differences in acoustic characteristics from impact and vibratory pile installation and their potential effects on the large yellow croaker (Pseudosciaena crocea)

“…Three-dimensional (3D) effects can vastly affect acoustic propagation in a complex shallow water environment. Underwater sound wave is affected by a series of geological features and physical oceanographic processes and can produce horizontal reflection, refraction, and diffraction (Oliveira et al, 2021). Because variation in water depth and geological features in the study area is small, the 3D sound propagation effect is ignored in the present study.…”

Three-dimensional acoustic propagation of noise from impact pile driving in a complex costal environment and its effects on large yellow croaker (Pseudosciaena crocea)

“…Underwater sound propagation in shallow-water environments, however, can be greatly impacted by threedimensional (3D) effects, such as physical, oceanographic, and geological features that can cause the horizontal reflection, refraction, and diffraction of sound. Therefore, 3D acoustic propagation models that can accurately predict the range within which underwater noise exerts an impact have been presented and used to study the propagation of the noise generated by pile driving (Lin et al, 2019;von Pein et al, 2019;Oliveira et al, 2021). Based on the governing equations and numerical schemes, 3D underwater acoustic models can be divided into three main groups: PE, normal mode, and ray-and beam-tracing models (Oliveira et al, 2021).…”

“…Therefore, 3D acoustic propagation models that can accurately predict the range within which underwater noise exerts an impact have been presented and used to study the propagation of the noise generated by pile driving (Lin et al, 2019;von Pein et al, 2019;Oliveira et al, 2021). Based on the governing equations and numerical schemes, 3D underwater acoustic models can be divided into three main groups: PE, normal mode, and ray-and beam-tracing models (Oliveira et al, 2021). However, the study of the 3D acoustic propagation of impact pile driving noise is still in its infancy (Porter, 2019).…”

Three-dimensional acoustic propagation model for shallow waters based on an indirect boundary element method

“…The importance of these effects has been early recognised [1,2] and even emphasized by at-sea and/or atlaboratory measurements. [3] A great variety of models have been developed to estimate underwater sound propagation in 3D scenarios which, according to their governing equations and numerical approaches, can be categorized into three main groups, [4] namely, (a) extended parabolic equation (PE) models, such as the efficient marching solution based on the parabolic equation [5] that has been applied to a local and a global ocean environment; [6,7] (b) normal mode models; [8][9][10][11] and (c) ray and beam tracing models. [12,13] However, modelling acoustic propagation for 3D environments is still a significant two-fold challenge due to both the difficulties associated with a thorough comprehension of the physical phenomenon and the high computational time costs.…”