Echolocation is the ability of an animal to sense its surroundings using reflected sounds, called echoes . Echoes can be used to determine the distance and direction to objects in the animal’s environment. Echolocation can also reveal such fine details as size, form, and surface texture. Only a few kinds of animals rely on echolocation, especially when it is too dark to use their eyes.
An animal may send out a sound and listen for the echo bouncing off something nearby. The animal can determine the object’s distance by how long it takes the echo to return. If the echo is heard quickly, the object is close. If the echo is delayed, the object is farther away. The direction to the object is determined using the loudness of the echo. For example, if the echo is louder to the left than to the right of the animal, then the object is located to the left.
At night, most bats use echolocation to find their food and to avoid obstacles while flying. Some whales and dolphins use echolocation to detect their prey and other creatures in deep, murky water where there is little light. A few birds, such as the oilbird of South America, nest inside caves where it is always dark. These birds make clicking sounds and use the echoes to help avoid crashing into the cave walls. Some human beings who are blind are able to detect large obstacles by listening for echoes after clicking their tongue, tapping a cane, or snapping their fingers.
When used underwater, echolocation often is called sonar instead. Some machines employ sonar . For example, submarines can give off a pinging sound, using the echo to locate ships or icebergs. Boat captains use sonar devices called depth finders to determine how close their vessel is to the ocean bottom.
