An elephant seal rookery is a noisy place. The vocalizations of adults of both sexes and the pups are described as well as their functions. Elephant seals have good hearing in air and in water and are also unusually sensitive to sounds. This is especially the case because their deep diving puts them smack in the middle of the deep sound channel where low-frequency sounds travel most efficiently and can be heard thousands of miles away. This may make them prone to disturbance by sources such as ship traffic, air guns from petroleum exploration, and US Navy operations.