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There has been a growing concern in recent years about the effects of anthropogenic noise due to marine pile driving on underwater wildlife. Current guidelines for mitigating hydroacoustic effects associated with these events are based upon relatively simple transmission loss formulations. The advantage to these guidelines is that computing transmission loss using their prescribed methods is not labor intensive, but their disadvantage is that they may not take all variables into account. Because of this, it may be possible to improve transmission loss computations. To better-characterize marine pile driving sound transmission loss, a unique in-water instrumentation system was developed. This system consists of several hydrophone-equipped buoys that transmit sound data to a field team in real time via a wireless network. The sound data are also recorded onboard the buoys along with geospatial data and water temperature data at depth. Testing was conducted using this buoy system at various water-based pile driving sites throughout Florida and sound data were used to compute transmission loss as a function of distance from the sound sources to utilize data from these sites to improve the knowledge base associated with generating mitigation guidelines. This research found that the coefficients used to calculate the simplified transmission loss model were consistently above those recommended by the current set of guidelines. Future areas of improvement and additional testing are recommended to address the growing concern of anthropogenic noise on underwater wildlife species and the effects of underestimating the actual transmission losses.

CIVINS (Civilian Institutions) Thesis document, There has been a growing concern in recent years about the effects of anthropogenic noise due to marine pile driving on underwater wildlife. Current guidelines for mitigating hydroacoustic effects associated with these events are based upon relatively simple transmission loss formulations. The advantage to these guidelines is that computing transmission loss using their prescribed methods is not labor intensive, but their disadvantage is that they may not take all variables into account. Because of this, it may be possible to improve transmission loss computations. To better-characterize marine pile driving sound transmission loss, a unique in-water instrumentation system was developed. This system consists of several hydrophone-equipped buoys that transmit sound data to a field team in real time via a wireless network. The sound data are also recorded onboard the buoys along with geospatial data and water temperature data at depth. Testing was conducted using this buoy system at various water-based pile driving sites throughout Florida and sound data were used to compute transmission loss as a function of distance from the sound sources to utilize data from these sites to improve the knowledge base associated with generating mitigation guidelines. This research found that the coefficients used to calculate the simplified transmission loss model were consistently above those recommended by the current set of guidelines. Future areas of improvement and additional testing are recommended to address the growing concern of anthropogenic noise on underwater wildlife species and the effects of underestimating the actual transmission losses., CIVINS, CIVINS, CIVINS, Lieutenant, United States Navy, Approved for public release; distribution is unlimited.