Acoustic model for monitoring marine noise

Acoustic Propagation Measurement and Modeling in Puget Sound to Support Noise Environmental Impact Efforts

Researchers are refining and testing an underwater sound propagation model, which can be used to protect marine mammals from construction noise.

Principal Investigator

Peter Dahl, University of Washington, Applied Physics Laboratory and Department of Mechanical Engineering

Co-Principal Investigator

Per Reinhall, University of Washington, Department of Mechanical Engineering

Project

The researchers are refining a new noise-propagation model they developed using measurements taken at various distances and depths during recent construction in Puget Sound. This model accounts for bathymetry and seabed sediment composition, which can affect sound propagation. They incorporated sediment maps of Puget Sound into the model and applied it to similar shallow water sites on the East Coast.

Research Updates

Background

Underwater noise from marine construction can threaten marine mammals such as killer whales and other sensitive species. Developers must establish monitoring plans to protect animals from harmful noise levels. Current monitoring plans are based on a simple model for underwater sound transmission that may not accurately estimate levels within tens of square kilometers. Use of this simple model can add significantly to a construction project’s cost and timeline without improving protection for marine mammals and other species.

Results

Initial results show that the shape of the zone of elevated noise levels can change with the seasons. They demonstrate good agreement between the model and actual underwater noise measurements, in contrast to predictions based on the traditional model. The Washington State Department of Transportation is waiting to adapt its underwater construction protocols to the new model once it is fully tested.