Currently, the Department of Defense (DoD) lacks scientifically defensible tools concerning the safe operation of many of it’s training and testing systems in the presence of marine mammals. There is very little direct information about what sound frequency-intensity combinations do to damage the hearing ability of marine mammals.

Through this project, Navy researchers expect to directly assess and predict the effects of military noise on marine mammals.

Before the effect of human activity on marine mammal’s ears can be evaluated, it is important to determine three things: the status of hearing in wild populations, what natural hearing changes can be expected in any given marine mammal as it ages, and what hearing pathologies commonly affect these animals. Otopathological analyses of marine mammals ears will be performed in order to ascertain their conditions. Using the otopathological analyses of baleen whale’s ears, a biomimetic model of auditory responsiveness to DoD sound types will be created. This model will simulate a baleen whale audiogram, and thereby, determine hearing responses to various well-defined military sound types across the bandwidth of whale vocalizations and the potential masking of whale communication calls. Statistical sampling models and acoustical classification algorithms using the data collected will be developed. The U.S. Navy’s Integrated Undersea Surveillance System (IUSS) for the mapping of the distribution of whales in the Southern California region will be activated.

Upper Panel: North Pacific Humpback Whale Lower Panel: Segment of Humpback Song Recorded Using Southern California SOSUS Arrays

Information on the cetacean sensory processes, performance, and mysticete (baleen whale) auditory morphology was obtained based on otopathological analyses of baleen whale ears. These results have provided the first detailed analyses of baleen whale ears, the first models of baleen whale auditory sensitivity (“WhalEar”), and application of the model to prediction of sensitivity of baleen whales to DoD sound types. The Smart Whale Acoustic Monitoring (SWAM) system was developed to automate the detection and classification of selected whale vocalizations using IUSS Imaging assets.

Predictive models and important mitigation tools will be developed using the new information about the effects of DoD sound types on marine mammal auditory anatomy and acoustic ecology.