Dolphins use echolocation for communicating with one another and for locating objects in their surrounding environments. Regardless of whether dolphins use echolocation for social purposes, such as communication, or for finding and avoiding obstacles, the mechanism of echolocation uses the same techniques. Dolphins generate beams or waves of clicking sounds, then pause to wait for a response, either from another dolphin or from an object.
Dolphins emit noises for echolocation by creating tiny vibrations with their phonic lips. This movement is similar to the humming sounds that humans produce, but it produces a much more complex range of sounds. After emitting sounds, dolphins pause for a few seconds to receive important feedback about their surroundings. Depending on the length it takes for a wave to produce an echo and the duration of the echo produced, dolphins can identify the size, shape and distance of objects, including stationary items such as coral reefs and the ocean floor.
Dolphins use echolocation to check the speed at which they are traveling (relative to nearby objects) and also to track the path of creatures moving toward them. They can even identify the internal structure or composition of objects (lighter weight objects produce more echoes and vibrations) to get an understanding of their surroundings.