There Are Two Reasons Echolocation Works
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.
The second reason echolocation works is that humans, on average, have excellent hearing. We hear better than we see. Much better. On the light spectrum, human eyes can perceive only a small sliver of all the varieties of light - no ultraviolet, no infrared. Converting this to sound terminology, we can see less than one octave of frequency. We hear a range of 10 octaves.
We can also hear behind us; we can hear around corners. Sight can't do this. Human hearing is so good that if you have decent hearing, you will never once in your life experience true silence. Even if you sit completely still in a soundproof room, you will detect the beating of your own heart.
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 1,000 feet away, a tree from 30 feet, a person from six feet. Up close, he can echolocate a one-inch 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.
He can hear the variation between a wall and a bush and a chain-link fence. Bounce a tennis ball off a wall, Kish says, then off a bush. Different response. So too with sound. Given a bit of time, he can echolocate something as small as a golf ball. Sometimes, in a parking garage, he can echolocate the exit faster than a sighted person can find it.
I accompanied Kish on several occasions as he cruised the busy streets of Long Beach. The outside world is an absolute cacophony. Every car, person, dog, stroller, and bicycle makes a sound. So do gusts of wind, bits of blowing garbage, and rustling leaves. Doors open and close. Change jangles. People talk.
Then there are the silent obstacles - what Kish calls urban furniture: benches, traffic signs, telephone poles, postal boxes, fire hydrants, light posts, parked vehicles. Kish hears the sonic reflections from his click even in a place teeming with ambient noise. 'It's like recognizing a familiar voice in a crowd,' he says. The load upon his mind is undoubtedly immense.
Yet he casually processes everything, constructing and memorizing a mental map of his route, all while maintaining an intricate conversation with me. It's so extraordinary that it seems to border on the magical.
When we walk into a restaurant - never a simple choice with Kish, since he's a strict vegan - he makes a much quieter click. Kish describes the images he receives as akin to a brief flick of the lights in a dark room; you get enough essential information - tables here, stairway there, support pillars here - to navigate your way through. 'It becomes as ridiculous for blind people to run into a wall as it is for sighted people,' he once wrote in his FlashSonar manual.
He strolls casually across the restaurant, making one or two more clicks as we approach our table, then sits down. It's both smooth and subtle. Kish says that it is rare a sighted person even notices he's making an unusual noise. Almost all blind people instantly do.
What people do notice about Kish is his long white cane. His blind person's cane. Using echolocation, Kish could get around without one. For most of his youth, in fact, he never carried a cane, seeking to avoid the stigma attached to it. Now, as he approaches middle age, he's come to believe that whatever can conveniently provide him with more information about his environment he will use.
Echolocation's chief liability is that it is not good at detecting holes in the ground, or small dropoffs, which a cane can do. There are also some figure-ground issues with echolocation - a park bench can 'disappear' when it's directly in front of a stone wall - and a cane, in essence, increases the length of your arm by as much as five feet.
Kish also keeps aware, during the day, of where the sun is striking him - a good way to determine direction - and how the cracks between sidewalk blocks line up; if you remain steadily perpendicular to them, you're not veering.
When it's all put together, says Kish, he has very rich, very detailed pictures in his head.
'In colour?' I ask.
'No,' he says. 'I've never seen colour, so there's no colour. It's more like a sonar, like on the Titanic.'
At his high school graduation in 1984, Kish was voted 'most likely to succeed.' Photo courtesy Daniel Kish
Kish can hardly remember a time when he didn't click. He came to it on his own, intuitively, at age two, about a year after his second eye was removed. Many blind children make noises in order to get feedback - foot stomping, finger snapping, hand clapping, tongue clicking.
These behaviours are the beginnings of echolocation, but they're almost invariably deemed asocial by parents or caretakers and swiftly extinguished. Kish was fortunate that his mother never tried to dissuade him from clicking. 'That tongue click was everything to me,' he says.
He has a vivid recollection of sneaking out his bedroom window in the middle of the night, at age two and a half, and climbing over a fence into his neighbor's yard. 'I was in the habit of exploring whatever I sensed around me,' he writes in his journal. He soon wondered what was in the yard of the next house. And the one after that. 'I was on the other side of the block before someone discovered me prowling around their backyard and had the police return me home to completely flummoxed parents.'
Kish was born in Montebello, California, into a difficult family situation. His younger brother, Keith, was also born with retinoblastoma - it's genetic, though neither of Kish's parents had the disease. Doctors managed to save enough of Keith's eyesight so that he doesn't need echolocation. He's now a middle school English teacher. Kish's father, who worked as an automobile mechanic, was a physically abusive alcoholic, and his mother left him when Kish was six.
'I was a violent kid,' says Kish. He frequently got into fistfights. 'I rarely lost. My strategy consisted of immobilizing opponents before they could hit me too often.' He went to mainstream schools and relied almost exclusively on echolocation to orient himself, though at the time neither he nor his mom had any concept of what he was doing. 'There was no one to explain it, there was no one to help me enhance it, and we all just kind of took it for granted,' he says. 'My family and friends were like, 'Yeah, he does this funny click thing and he gets around.' They called it his radar. Navigating new places, he says, was like solving a puzzle.
He rode his bike with wild abandon. 'I used to go to the top of a hill and scream 'Dive bomb!' and ride down as fast as I could,' he says. This is when he was eight. The neighbourhood kids would scatter. 'One day I lost control of the bicycle, crashed through these trash cans, and smashed into a metal light pole. It was a violent collision. I had blood all over my face. I picked myself up and went home.'
He was raised with almost no dispensation for his blindness. 'My upbringing was all about total self-reliance,' he writes, 'of being able to go after anything I desired.' His career interests, as a boy, included policeman, fireman, pilot, and doctor. He was a celebrated singer and voracious consumer of braille books. He could take anything apart and put it back together - a skill he retains.
Once, when I was driving Kish to an appointment with a student, the GPS unit in my car stopped working. Kish examined the unit with his hands, instructed me from the passenger seat how to get to the nearest Radio Shack, and told me which part to buy (the jack on the power cord was faulty). He was named 'best brain' in middle school and graduated high school with a GPA close to 4.0. He was voted 'most likely to succeed.'
He attended the University of California Riverside, then earned two master's degrees - one in developmental psychology, one in special education. He wrote a thesis on the history and science of human echolocation, and as part of that devised one of the first echolocation training programs. The ability of some blind individuals to perceive objects well before they could touch them was noted as early as 1749 by French philosopher Denis Diderot. He theorized it had something to do with vibrations against the skin of the face. In the early 1800s, a blind man from England named James Holman journeyed around the world - he may have been the most prolific traveller in history up to that point, Magellan and Marco Polo included - relying on the echoes from the click of his cane. Not until the 1940s, in Karl Dallenbach's lab at Cornell University, was it irrefutably proven that humans could echolocate.
The thesis was the first time Kish really studied what he'd been doing all his life; it was the beginning, as he put it, of 'unlocking my own brain.' He then became the first totally blind person in the United States (and likely the world) to be fully certified as an orientation and mobility specialist - that is, someone hired by the visually impaired to learn how to get around.
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