echolocation
n. the ability to judge the direction and distance of objects or obstacles from reflected echoes made by acoustic signals, such as footsteps, the tapping of a cane, or traffic noises. People with visual impairment can learn to develop this ability to find their way and avoid obstacles. Among nonhuman animals, both bats and marine mammals (e.g., dolphins) can locate objects by emitting high-pitched sounds that are reflected from surfaces of the physical environment and prey objects. High-pitched sounds provide better spatial resolution of an object than sounds of lower pitch but require more energy to travel the same distance. Thus, a bat can locate a mosquito but only at a short range. See also ultrasonic communication.