Automated model-based localization of sperm whale clicks

In previous work we described an algorithm based on an acoustic propagation model that was used for passive acoustic localization of vocalizing marine mammals. Differences between measured and modeled pair-wise time-differences of arrival were used to define an ambiguity surface that identifies the most probable whale location in a horizontal plane around an array. The algorithm has been successfully applied to humpback whale calls in deep water near Hawaii and blue whale calls in shallow water near California. In this work, we return to Hawaii to track another species of whale, the sperm whale, whose calls are brief, broadband clicks. Acoustic localizations are in close proximity in space and time to aerial observations of sperm whales. We were also able to verify the algorithm´s accuracy in a controlled source experiment at the Navy´s AUTEC range in the Bahamas. Recordings of sperm whale clicks were broadcast and successfully tracked. The localization accuracy of the model-based technique and traditional hyperbolic techniques is compared.