Underwater noise

Underwater Noise Assessments and Modelling

BMT Cordah has extensive experience in modelling underwater noise generated by offshore operations and assessing its potential impact on marine species.

Underwater noise generated by offshore operations can harm marine species. For example, it may cause temporary or permanent hearing damage, changes in behaviour, masking of important sounds such as communication and echolocation or mortality. As a result, it is often necessary for operators to assess the noise impacts of their activities.

BMT Cordah regularly conducts underwater noise impact assessments in support of Environmental Impact Assessments (EIAs) for North Sea oil and gas developments and renewables.

For activities including:

  • Piling
  • Seismic surveying
  • Drilling
  • Vessel activity
  • Installation of subsea infrastructure

Stand-alone noise studies for offshore operations in UK and international waters (international work includes projects in Tunisia, Mauritius, Spain and Norway)

Underwater noise assessments are conducted for a wide range of marine species including whales, dolphin, seals, fish, invertebrates and human divers.

Numerical Underwater Noise Modelling Consultancy

BMT Cordah’s Noise Modelling Consultancy models the propagation of noise into the surrounding environment.

Noise sources: Likely sources of noise identified and characterised in terms of frequency range and sound level generated. For multiple noise sources a cumulative noise level is modelled.

Noise propagation: The level of noise likely to be received at distance from the operations is estimated using underwater noise propagation modelling.

Graphics: High quality tables and graphics to illustrate the propagation of underwater noise into the environment.

Environmental impact assessment

Hearing ability is species-specific. Therefore, the sound levels and frequencies likely to cause harm vary with species. This is accounted for in an impact assessment.

To predict the distance from a source within which noise may cause harm, BMT Cordah combines estimated species-specific received sound levels with threshold noise levels for injury and disturbance. 


The Offshore Marine Conservation (Natural Habitats, &c) Regulations 2007 make it an offence to deliberately capture, injure or kill any European Protected Species, including whales, dolphins and porpoises. As a result, an EIA for an offshore operation must assess the potential noise impact on marine mammals.

BMT Cordah uses latest Joint Nature Conservation Committee (JNCC) and International Finance Corporation (IFC) World Bank guidelines to conduct noise impact assessments according to up-to-date scientific knowledge.

Mitigation measures

As part of an underwater noise assessment, BMT Cordah advises on mitigation measures, making proper use of national and international legislation and guidelines. Mitigation measures include use of marine mammal observers, soft-start of piling and airgun use and planning of operations to be conducted outwith sensitive periods for marine animals. 

Noise measurement

BMT Cordah is able to undertake projects in partnership with Kongsberg Maritime, which has designed and developed the Acoustic Monitoring Buoy System (AMBS) to effectively measure, process, monitor & record underwater noise levels in real time. This information is used to model the noise environment and identify potential risk to sensitive receptors. 

BMT Cordah’s customers and projects for noise related studies and impact assessment

Talisman Energy (UK) Ltd Noise impact assessment for Beatrice Demonstration Wind Farm, ­ Nexen Petroleum Ltd Noise impact assessments for EIAs, ­ Anadarko Petroleum Corporation Noise assessment for seismic survey in Tunisian waters, Endeavour Energy UK Ltd Noise impact assessment for EIA, ­ Environmental Assessment and Management, Tunisia Training on noise impact assessment, Client confidential (various) Noise impact assessment for offshore operations including piling, construction and vessels ­ Client confidential Noise characterisation study for drilling campaign in Spanish waters, Client confidential Noise impact assessment in support of EIA for seismic survey on UKCS, BG Group Noise impact assessments for EIAs

Underwater Noise Assessments and Modelling

Underwater Noise Assessments and Modelling

This is a brochure covering BMT Cordah's work in Underwater Noise Assessments and Modelling.