Controlled exposure experiments to determine the effects of noise on marine mammals

Controlled exposure experiments or CEEs are an important technique for determining the responses of animals to signals that are not part of their own communicative repertoire. CEEs are useful for establishing the relationship between acoustic dosage and behavioral response, a critical element of risk assessment, similar to dose:response studies for exposure to chemicals. CEEs share some properties with "playback" experiments; the main difference between playbacks and CEEs is that CEEs involve the careful titration of acoustic exposure to the point where specific responses are observed. Most CEEs are applied research designed to answer questions related to wildlife conservation. The utility and power of CEEs lies in providing a sensitive measure of causal relationships between behavioral responses and particular stimuli. We review design features and experimental methods for CEEs, limiting our scope for this paper to studying the effects of underwater noise on wild marine mammals.