Mass strandings have occurred alongside naval exercises involving medium-frequency sonar. Injuries to the acoustic organs of several species of whales result in their death (Wright et al, 2007). Acoustically induced strandings can also be observed in other cetacean species and the likelihood that noise could lead to strandings and/or deaths of marine mammals lies beyond this. naval sonar. For example, seismic noise has been implicated in the stranding of beaked whales (Hildebrand, 2005). Hearing damage Temporary hearing loss is induced by exposure to anthropogenic noise. This is called a temporary threshold shift (TTS), if the noise is loud or long enough. The longer the duration and/or the higher the sound level, the higher the risk of TTS. Hearing damage can become permanent following a very loud sound event or even if exposure is prolonged or repeated, also known as permanent threshold shift (PTS). Captive beluga and beluga whales have been studied to show that TTS is caused by an impulsive noise that is both tonal and of very short duration, although the sound is integrated....