Echolocation, the process of determining the distance and direction of objects by using sound. This article is concerned with echolocation as used by animals. For information about an artificial form of echolocation used by humans, s.

Echolocation is performed by certain animals to locate food or obstacles in darkness, such as in caves and in the ocean. These animals, which include bats, toothed whales, oilbirds, cave swiftlets, and shrews, produce sounds and then listen for echoes. The delay between the emission of a sound and the arrival of an echo indicates the distance of an object.

Bats and toothed whales have specialized body parts that emit and receive ultrasounds (sounds that cannot be heard by humans). The other animals that use echolocation produce sounds that are audible to humans.

A characteristic example of bat echolocation is that of horseshoe bats. Horseshoe bats emit pulses of sound through nasal structures known as nose leafs; the external portions of their ears are especially large, allowing even faint echoes to be heard. Echolocation enables bats to detect small differences in the sizes and shapes of objects and to determine the velocity of a moving object.

A characteristic example of whale echolocation is that of bottle-nosed dolphins. A bottle-nosed dolphin emits a variety of sounds through its bulbous forehead, known as a melon. Echoes are detected through the lower jaw, which has sound-conducting tissue connected to the ear.