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Bats and dolphins find their way around with natural sonar systems that enable them to perceive the dimensions of their world with reflected sound. So why not humans? It's an idea that Leslie Kay, an expert in submarine sonar from New Zealand, has devoted nearly 40 years to researching. He's developing sonar systems to help the visually impaired navigate their darkened world.
Due to radical improvements in his technology, Kay's latest device may be on the verge of becoming accepted by the blind as an essential mobility tool alongside the venerable cane and seeing-eye dog. Dubbed KASPRA, for Kay's Auditory Spatial Perception Aid, the device is worn like a headband. It emits frequency-modulated ultrasound signals similar to those of some animals. Embedded a few inches apart in the band are two receptors that produce stereophonic sounds in earphones, just as the distance between our eyes produces stereo visual images permitting depth perception. The sounds change in pitch to reflect the distance and dimension of objects around the KASPRA wearer.
TELLING LEAVES FROM BRANCHES. According to Kay, who conducts research at the Spatial Sensing Laboratory at Bay Advanced Technologies Ltd. in Russell, New Zealand, KASPRA is six times more sensitive than its predecessor. In tests, blind children have used KASPRA to ride bikes through obstacle courses, and one blind child even batted a softball. Kay has high hopes that KASPRA will give the blind the previously unimaginable ability to accurately perceive and visualize their physical surroundings, as bats and dolphins do.
KASPRA works similarly to sonar systems used by these animals. In the same way we see with light, the sensors detect a unique signal from every object in the environment. The leaves and branches of a bush, for example, will each have a distinct signal. The tiny echoes are converted into tones with a pitch representing the distance to each leaf. The brain seems to be able to convert this changing "tone complex" into a spatial representation, just as it does with eyesight.
"The stage has been reached when blind persons can walk about like sighted persons do in a busy shopping area, going in and out of shops. They'll be able to recognize their location relative to the many landmarks on the way," Kay says.
"ACOUSTIC PICTURE." Kay, who is nearing 80, developed his first sonar device for the blind in the 1970s. Called the SonicGuide, it looked like a pair of eyeglasses. Similar to KASPRA, a module over the nosepiece radiated pulses of high-frequency ultrasound. Two matching receivers captured the reflected signals and transmitted them as audible sound to a pair of earphones. By learning to interpret the changing echoes, wearers would develop an "acoustic picture" of their surroundings.
But the blind didn't share Kay's vision. Fewer than 1,000 of the units were sold before they were finally withdrawn from the market in 1998. "The technology was never marketed or promoted very well," says Daniel Kish, who teaches the blind techniques for getting around Los Angeles and is blind himself. "Many teachers in the field were intimidated by it, so it was not passed on to students. Kay knew nothing of the issues facing the blind when he began his work -- even the blind, at that time, weren't clear about what they needed."
The rejection didn't prompt Kay to stop his research, however, and KASPRA is the fruit of that labor. On Dec. 5, he described his latest invention and what it can accomplish in a special lecture before the annual conference of the Acoustical Society of America in Newport Beach, Calif. Kay reported that tests with the device have turned up some impressive results.
3D DESCRIPTIONS. Although some users were initially confused and annoyed by the rapidly changing tones, especially when moving their head in a "looking motion," according to Kay, most were eventually able to describe three-dimensional images from the signals. In one test, 14 blind schoolchildren with very low to high intelligence were able to navigate with KASPRA after 20 hours of training in 40 exercises over several weeks.
Kish, for one, is convinced the blind now are ready to embrace the new technology. "Kay's technology is truly a breakthrough in thinking that occurred long before its time," says Kish, who has been named executive director of a new nonprofit corporation called World Access for the Blind. The group, which will likely be based in Southern California, will work to bring together experts in the blindness field to make innovative technologies, such as KASPRA, available.
"We believe we can bring movement for the blind to a level never thought possible," Kish says. "The impact on the blind's functional capacities could be staggering." If he's right, someday soon blind people will be playing soccer and baseball and racing through the woods on mountain bikes.
Copyright 2000, by The McGraw-Hill Companies Inc. All rights reserved.
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