Sonar, an acronym for “SOund NAvigation Ranging,” is a method of using sound waves to determine the distance an object is from a transmitter of sound. The sonar contains a transducer that converts an electrical impulse to sound when it transmits and a sound wave to an electrical impulse when it receives. Sound waves, usually brief pulses of ultrasound, are emitted from the transducer, reflected off an object, and reflected back to the transducer. Electronic circuits measuree the length of time it took for the sound waves’ round trip, and use the speed of sound to calculate the distance the object is from the transducer.

Sonar is used predominantly as a navigational tool by humans and animals. Dolphins and bats, among other animals, use sonar for navigation, hunting, and communicating. Machines such as depth-finders on boats, distance meters used in real estate and construction, and motion detectors for security devices all employ sonar.