Dolphins hear sounds with wavelengths that range from 1 to 150 kilohertz. This is much larger than the human range of 0.2 to 17 kilohertz and reflects the fact that dolphins communicate using high-frequency sounds.
Dolphins' hearing plays a major role in the animals' ability to navigate by echolocation. As dolphins swim, they emit high-pitched clicks that echo off objects in adjoining water. Recent research suggests that echolocation creates images of objects in dolphins' brains and is integrated with the animals' visual center, allowing them to relate the things they hear to the things they see. Dolphins may use this ability for finding hidden fish as well as navigation.