Bats do it. Dolphins do it. And apparently so do some humans. A few gifted people — all blind — have developed the ability to “see” nearby objects by creating sounds (e.g., clicking) and listening to the return echoes to sense their size, distance and density. Dan Kish, who lost both eyes in infancy to retinoblastoma (an aggressive form of eye cancer), is so skilled at echolocation (or “FlashSonar” as he likes to call it) that he can bike through crowded city streets and down steep mountain trails. He even camps alone in the wilderness for weeks on end.