Human Echolocation

This person lost his vision early in life and has learned to navigate his surroundings as good as any seeing person using echolocation. By making clicks with his tongue, he can literally hear the objects in front of him in much the same way that a dolphin or a bat navigates.

From Neurophilosophy:

WE all know that bats and dolphins use echolocation to navigate, by producing high frequency bursts of clicks and interpreting the sound waves that bounce off objects in their surroundings. Less well known is that humans can also learn to echolocate. With enough training, people can use this ability to do extraordinary things. Teenager Ben Underwood, who died of cancer in 2009, was one of a small number of blind people to master it. As the clip below shows, he could use echolocation not only to navigate and avoid obstacles, but also to identify objects, rollerskate and even play video games.

Very little research has been done on human echolocation, and nothing is known about the underlying brain mechanisms. In the first study of its kind, Canadian researchers used functional magnetic resonance imaging (fMRI) to monitor the brain activity of two blind echolocation experts. Their findings, published today in the open access journal PLoS ONE, show that echolocation engages regions of the brain that normally process vision.