Echolocation

Echolocation is the use of emitted sounds and returning echoes to locate objects. It can reveal an object's direction, distance, size, and movement.

Time-of-flight: A method for estimating distance from the time a signal takes to travel to a target and return. The delay between an emitted sound and its echo estimates the target's range.
Lazzaro Spallanzani: An Italian naturalist whose experiments in the eighteenth century investigated how bats navigate in darkness. His experiments helped establish that bats rely on senses other than vision to avoid obstacles.
Bat echolocation: The use of ultrasonic calls and returning echoes by bats to navigate and detect prey. Bats provide a richly varied case of active echolocation in air.
Passive sonar: A sonar method that detects sounds produced by other sources without emitting probing signals. Unlike echolocation, it locates targets by listening rather than producing echoes.
Doppler effect: A change in observed frequency caused by relative motion between a wave source and an observer. Frequency shifts in returning echoes can reveal whether a target is moving.
Donald Griffin: An American zoologist who helped demonstrate that bats use high-frequency sounds for navigation and prey detection. Griffin introduced the term echolocation and helped establish its role in bats.
Dolphin echolocation: The use of clicks and returning echoes by dolphins to detect and discriminate underwater objects. Dolphins apply echolocation in water, where sound travels efficiently.
Vision: The sensory process by which organisms detect and interpret light to perceive their surroundings. Vision uses reflected light, while echolocation uses returning sound.
Beamforming: Signal processing that combines measurements from multiple sensors to emphasize signals arriving from particular directions. Directional hearing helps locate echoes arriving from different angles.
H. D. Denzinger: A German zoologist known for research on bat echolocation and its evolution. His work examines how bat calls and hearing adapt to different ecological settings.

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