Animal echolocation in the external ear. There are two hypotheses about the evolution of echolocation in bats. The first suggests that laryngeal echolocation evolved twice in Chiroptera, once in the Yangochiroptera and once in the horseshoe bats (Rhinolophidae). The second proposes that laryngeal echolocation had a single origin in Chiroptera, was subsequently lost in the family Pteropodidae (all megabats), and later evolved as a system of tongue-clicking in the genus "Rousettus". Individual bat species echolocate within specific frequency ranges that suit their environment and prey types. This has sometimes been used by researchers to identify bats flying in an area simply by
Human echolocation later participated in experiments in facial vision (White, et al. 1970). About 1998, he visited the Auditory Neuroethology Laboratory at the University of Maryland and was interviewed about his experience with facial vision. The researchers in the lab study bat echolocation and were aware of the "Wiederorientierung" phenomenon described by Griffin (1959), where bats, despite continuing to emit echolocation calls, use path integration in familiar acoustic space. Scadden indicated that he found echolocation required extra effort, and would not use it to navigate in familiar areas unless he was alert for obstacles, thus providing insight into the bat behavior. The