Like a Bat, Blind Man Uses Sound to 'See'
Daniel Kish uses echolocation to sense his surroundings.
May 26, 2011— -- Daniel Kish was 13 months old when he lost his eyes to cancer, but that didn't stop him from getting around. By making a clicking noise with his tongue and listening for the echo, Kish could figure out where things were around him, a skill that baffled his parents.
"I don't know that they really noticed the clicking right away," said Kish, 45. "I think they just noticed that I was able to find my way around."
Kish has since mastered the skill, known as echolocation. Like a bat, he uses sound to see.
"Sound is like light in that they're both waves of energy," Kish said. "These waves of sound bounce off things in the environment, and when they return they actually carry with them an imprint of what they've encountered."
Kish of Long Beach, Calif., said his brain learned to interpret the information contained in the echoes and use it to construct images.
"It's basically a representation of what's taking up space in the environment based on location, dimension and depth of structure," meaning the solidness of objects, Kish said. "The image that you get," which is colorless and has no grayscale, "basically combines those characteristics."
As president of World Access for the Blind, a non-profit organization based in Long Beach, that helps blind people learn to "get around more effectively and lead their lives with greater freedom," Kish teaches other blind people how to echolocate. And to better understand how the technique works, he teamed up with Canadian scientists for a brain imaging study.
"Dan was eager to come up and explore the possibility that there may be some interesting things happening in his brain while he's echolocating," said Mel Goodale, director of the Centre for Brain and Mind at the University of Western Ontario in London, Canada, and senior author of the study published Wednesday in PLoS One.
Using magnetic resonance imaging, Goodale and colleagues studied the pattern of activity in Kish's brain when he was listening to clicks and echoes. Instead of activating his auditory cortex, the area responsible for interpreting sound, the clicks and echoes appeared to activate Kish's visual cortex.
"It was really quite amazing," Goodale said. "It looked like it was recruiting a good chunk of the primary visual cortex in his brain."
Kish said he hopes the study adds credibility to his approach, which could attract the resources needed to deliver it more widely.
"Right now, most of the funding goes toward vision preservation and restoration, which is fine for those individuals for whom it will work, but it won't work for everyone," Kish said. "We can help blind people see their environment now."
Kish showed off his incredible talent on the Discovery Channel show "Is It Possible" by finding a rubber ball in the middle of a field. But while echolocation allows him to detect objects up to 100 yards away, he hasn't ditched his white cane.
"We can kind of think of echolocation as being sort of far vision; it's good for things that are far away and off the ground," he said. "The cane is good for things that are nearer and at ground level."
Kish and Goodale will reconnect for a follow-up study in June aimed at teasing out how the brain system interpreting the echoes is organized.
"Blind people should realize that this is an opportunity; that you can do quite a bit with echolocation," Goodale said "I think it's important to get it out there. It may not be for everyone, but it's worth a try."
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