With echolocation, the blind use sound energy to see

BOSTON – Daniel Kish discussed here at Optometry’s Meeting how he uses echolocation to “see” his surroundings through the echoes created from clicking his tongue.

Kish, president of World Access for the Blind (WAFTB), was born with retinoblastoma and had both eyes removed by the time he was 13 months old; however, he now can travel alone, using his well-honed echolocation, a skill he teaches others.

WAFTB promotes public awareness of the capabilities of the blind community and instruction to enable blind people to create freedom in their lives by navigating the world in better ways. The organization helps train people to use a clicking of the tongue to produce sound to see the world around them, what they call FlashSonar, which WAFTB considers a more technically refined form of echolocation.

During his talk, Kish asked attendees to close their eyes. He made a series of three loud clicks in the ballroom as he moved his body position. Then he asked what was different about the clicking sounds and if the echoes sounded different. Very few people in the room said that they heard multiple echoes, which was the correct answer, according to Kish.

“I have students who can tell you [precisely], as well as a computer could, how many echoes there were,” he said.

“It’s interesting, because blindness is the result of a mistake,” he continued. “Blindness doesn’t happen because it’s supposed to. Something went wrong. For me, someone failed to noticed the tumors growing in my eyes before it was too late.”

The quote, “Success is built on a mountain of mistakes” came to mind when Kish considered his direction for his speech, he explained.

“The difference between greatness and mediocrity is often how an individual views a mistake,” he said. “So, if blindness is a mistake, which many of us would say, then what would be the results of blindness? Do they follow the same mistake? Are blind peoples’ lives full of mistakes? Are blind people mistakes?”

Kish played a video that was featured on The Weather Channel.

“We see with our ears...” a child featured in the video described.

“Echolocation is a way of seeing with sound,” Kish said. “You’re using flashes of sound, instead of flashes of light. Sound is energy, light is energy. Sound energy reflects from surfaces in the environment and returns to the listener, containing patterns, containing impressions, from those surfaces.”

One scene showed a blind man outside with a journalist. The man was able to correctly identify a tree in front of him after making a few clicks. The journalist was shocked.

“Over here I see a tree,” the blind man said. “It washes in. Once you click at the trunk of the tree it hits the trunk and wraps around. It washes up and when it comes back to you [the sound] is going to shake...you get this sound waterfall effect.”

Next in the video, Kish is shown walking down a residential street, in front of a house with a picket fence. He accurately identifies a curve in the fence and the direction in which it is curving.

WAFTB has taught perceptual navigation to more than 10,000 blind people, their families, instructors and interested members of their communities across the U.S. and in more than 40 countries, according to the WAFTB website.

“Active echolocation is a very specific form of self-directed and self-determined echolocation to optimize the quality of echoes from the environment and is very much in the control of the user,” Kish added. “It’s about redeploying the visual brain, even though it’s never received a visual input.”

Researchers studied which part of Kish’s brain was activated while echolocating. However, in studying this, a challenge arose. Kish could not lay in an MRI machine with nothing to echolocate. Scientists adapted, using miniature microphones implanted in Kish’s ears, recording the clicks and echoes from his surrounding environment.

They then played the sounds back to Kish out of order to see if he still knew what the objects were. He did.

The researchers also analyzed brain activity as Kish clicked and listened. The visual cortex was activated, and they also found that the visual cortex was incredibly sensitive to the echo-only sound files. The researchers determined that normal sounds do not activate the visual cortex as strongly as the echoes.

V1, an area of the visual system in the brain, creates a spatial map that directly reflects the eye’s retina, the researchers explained.

“What we’ve learned so far in the teaching that I’ve done and through my instructors and WAFTB is that it’s crucial to understand and be able to impact the adaptation process of the perceptual system, which we believe is parallel for stroke recovery or traumatic brain injury wherein the brain readapts around the area that has been affected,” Kish said. “And one of the ways to get the brain to do that is to intensify the utility of those remaining functions.”

Neuroperceptual adaptation happens quickly, Kish said. He begins to see changes in hours, sometimes minutes, in some people.

“We have interest in furthering this adaptation process...those interested in developmental optometry, neuro-optometry, check us out and we’d be happy to have a dialogue,” he added.

For a blind person, he explained, when the lights go out, the person can turn their lights back on in their brain with this technique.

He concluded with a quote by Charles Austin Beard: “When it is dark enough, you can see the stars.” – by Abigail Sutton

Reference :

Kish D. OD talks: Through a patient’s eyes. Presented at: Optometry’s Meeting; June 29 – July 2, 2016; Boston.

Disclosure: Kish is the lead founder and President of World Access for the Blind. He has authored several articles, periodicals, journal articles and co-authored a textbook.