This is brilliant:

To see him speed down hallways and make sharp turns around corners is to observe a typical teen – except, that is, for the clicking. Completely blind since the age of 3, after retinal cancer claimed both his eyes (he now wears two prostheses), Ben has learned to perceive and locate objects by making a steady stream of sounds with his tongue, then listening for the echoes as they bounce off the surfaces around him. About as loud as the snapping of fingers, Ben’s clicks tell him what’s ahead: the echoes they produce can be soft (indicating metals), dense (wood) or sharp (glass). Judging by how loud or faint they are, Ben has learned to gauge distances.

The technique is called echolocation, and many species, most notably bats and dolphins, use it to get around. But a 14-year-old boy from Sacramento? While many blind people listen for echoes to some degree, Ben’s ability to navigate in his sightless world is, say experts, extraordinary. “His skills are rare,” says Dan Kish, a blind psychologist and leading teacher of echomobility among the blind. “Ben pushes the limits of human perception.”

From: People.com