Daniel Kish lost his eyesight when he was 13 months old. For most of his youth, he functioned fine without a walking stick. He mountain bikes. He camps alone. He moves through cities handily. All thanks to advanced echolocation abilities.
According to Michael Finkel (in an article for Men's Journal), Kish can sense everything around him by clicking with his mouth and listening to the quality of the sound, kind of like a dolphin. He calls it FlashSonar. Kish started clicking when he was two—many blind children do—but unlike others, he wasn't discouraged from doing so (organisations for the blind don't like him very much because they think it promotes a bad image of the visually handicapped). Ultimately, it developed into a tool. A very useful tool. He wrote a master's thesis on echolocation for chrissakes.
Kish's click is a thing of beauty - he snaps the tip of his tongue briefly and firmly against the roof of his mouth, creating a momentary vacuum that pops upon release, a sound very much like pushing the igniter on a gas stove. A team of Spanish scientists recently studied Kish's click and deemed it acoustically ideal for capturing echoes. A machine, they wrote, could do no better..
Does echolocation even work for humans? It's a function we haven't developed because we haven't had to.
There are two reasons echolocation works. The first is that our ears, conveniently, are located on both sides of our head. When there's a noise off to one side, the sound reaches the closer ear about a millisecond - a thousandth of a second - before it reaches the farther ear. That's enough of a gap for the auditory cortex of our brain to process the information. It's rare that we turn the wrong way when someone calls our name. In fact, we're able to process, with phenomenal accuracy, sounds just a few degrees off-center. Having two ears, like having two eyes, also gives us the auditory equivalent of depth perception. We hear in stereo 3-D. This allows us, using only our ears, to build a detailed map of our surroundings.
And because Kish took the time to finely hone this ability, he's able to live a very capable life that few of us would be able to replicate if we were to go blind tomorrow.
Kish does not go around clicking like a madman. He uses his click sparingly and, depending on his location, varies the volume. When he's outside, he'll throw a loud click. In good conditions, he can hear a building 300 metres away, a tree from 10 metres, a person from two metres. Up close, he can echolocate a 2.5cm diameter pole. He can tell the difference between a pickup truck, a passenger car, and an SUV. He can locate trail signs in the forest, then run his finger across the engraved letters and determine which path to take. Every house, he explains, has its own acoustic signature.
For the entire story of Daniel Kish, be sure to check out the full article over at Men's Journal. You won't be sorry you did. [Men's Journal]
[Image via Shutterstock]