There has been growing recognition that atypical mass strandings of beaked whales may coincide with naval exercises that use mid-frequency sonar, but the causal chain of events has not been elucidated. Even less is known about potential risks to other species or for other signals. The proposed research is part of a collaborative research program whose long-term goals are to compare responses of beaked whales and other odontocetes to playbacks of mid-frequency sonar sounds and other anthropogenic and natural signals. The ultimate goals are to predict the distribution of species at risk from sonar, to define dose:response curves for risk to whales during exposure to naval sonars, and to suggest improvements for monitoring and mitigation. The specific data gap that this year aims to fill is a lack of baseline data from pilot whales. The study of large delphinids relatively easy to tag is important as results so far suggest they may have different responses to sonar, suggesting very different risk factors, compared to beaked whales. The behavior of the pilot whales is complex and variable enough, that even though the BRS and 3S projects together have more playbacks of sonar and killer whale sounds to them than any other species, we anticipate that considerably more work on baseline behavior will be needed to resolve issues around variability of response. Some pilot whales responded to playbacks of sonar and killer whale sounds by increasing their calling rates, and with increased social cohesion with less consistency in avoidance responses than the beaked whales tested. No sonar playbacks have been conducted with any beaked whale species outside of a naval range, where they frequently are exposed to naval sonars. Another goal is to conduct playbacks of sonar and killer whale sounds in areas with little sonar usage to Cuvier's beaked whale, Ziphius cavirostris, the species most represented in the record of atypical mass strandings associated with naval maneuvers.