Many animals (dolphins, bats, shrews, etc etc) can echolocate. That is, by emitting calls the environment and listening to the echoes of those calls that return from various objects near them. Some animals - for example dolphins - can not only locate objects, but can also determine what they are. This skill is as yet unexplained.
Object matching studies with dolphins verify that dolphins can in fact recognize objects using echolocation. Their ability to accomplish this feat is remarkable given the responsiveness of sound to myriad factors including air bubbles, temperature, salinity, density, ambient surfaces, and the multiple surfaces presented by an echolocated object itself. Indeed, echoes from different aspects of a one object can vary more from each other than do echoes from different objects (DeLong, Au, Lemonds, Harley, & Roitblat, 2006). These complications have made it very difficult, for example, for the U.S. Navy to a create a sonar system that recognizes objects as well as dolphins do, a goal that has led to many studies of dolphin echolocation in order to aid in the design of a man-made system that can mimic the dolphin. To date, no such system is available. The best sonar systems continue to exist only in cetaceans.
See: Echoic Object Recognition by the Bottlenose Dolphin. Comparative Cognition & Behavior Reviews, 3, 46-65.
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