Results of several recent studies including one conducted on killer whales by Holt et al. 2009 demonstrate that cetaceans respond to increases in environmental noise by increasing the amplitude, duration, and/or repetition rates of their acoustic signals. Potential energetic costs of vocal responses to noise have not been investigated in cetaceans. Drs. Marla Holt and Dawn Noren are conducting a study on the metabolic costs of sound production in bottlenose dolphins in Dr. Terrie William’s lab at UC Santa Cruz to study potential energetic effects of noise-induced vocal responses. In this study, metabolic rates are being measured in two trained bottlenose dolphins during periods of rest, vocal activity, and recovery. The dolphin’s are trained to produce either “loud” or “quiet” vocalizations on a given trial and results will be compared between the two conditions to determine if dolphins experience a metabolic cost when raising their voices. The results from this study will provide valuable data to address potential biological costs of anthropogenic noise exposure in cetaceans.