Noise assessments in the marine environment typically involve the interaction between underwater noise sources and marine species. It is often a requirement of planning consent that a detailed Environmental Impact Assessment (EIA) be undertaken to determine the likely effects of noise on these marine species.
Background noise levels in water bodies comprise a number of noise sources, including anthropogenic noise (often in the form of distant shipping noise). Whilst marine species can habituate to these constant low-level noises, louder noise sources can cause effects ranging from avoidance of an area (which may be a breeding area) to lesions of vital organs and death. These effects can be caused by high power sonar systems, explosions and pile-driving. The most common of these sources is pile-driving, with the use of an impact hammer producing extremely high noise levels of noise that can propagate long distances in the marine environment.
An EIA will require that the risks of noise exposure to marine species are properly assessed. This can involve anything from developing noise propagation models to on-site measurement of noisy activities to determining effective means of mitigation.