Dewald van Deventer tells me about going hiking with Daniel Kish, the granddaddy of human echolocation – a method of ‘seeing’ or acoustic navigation where a person uses clicking of the tongue (or cane, or any other object) to create small echoes of reflected sound that create a picture of the surrounding area. It’s similar to the sonar and animal echolocation used by bats, toothed whales and dolphins.
“It’s interesting,” Dewald says. “Sometimes I see things that he [Kish] doesn’t see; sometimes he sees things that I don’t see. That time, when he came to visit me, he saw a deer trail that I hadn’t seen, and we followed it. It was spectacular…”
Dewald hikes and bikes; he takes part in sports; he is a keen explorer out in nature and the wilderness, an accomplished pianist, and runs his own business, having returned from studying on sponsorship in Vancouver and Washington. He can tell you at some distance what is approaching and how fast, or whether there’s a steep drop coming up on a wilderness trail. Echolocation is so precise that a skilled person using it can locate any object to within about three degrees. According to Dewald, it’s no big deal to trace the outlines of a car without touching it (and probably tell you what kind it is; if not the make and model, then certainly whether it’s a hatchback, bakkie or stationwagon). On his second day of using echolocation, Dewald walked under a tree and counted the branches as he went.
“A lounge sounds different to an auditorium, to you as well,” he explains. “In a lounge there are carpets, couches, et cetera. It sounds small and closed. If I want to walk around in the room, I click to hear whether there are obstructions in my path. I have a cane, and I do use it. But if I walk into a room, I click to hear if there are openings in the walls. Doorways, windows, and of course what is in the room and what might be in my path…”
Dewald, now 29 and running a successful business as a piano tuner and repairman in Kempton Park and Bloemfontein, went blind at the age of 10. Echolocation is perhaps easier to learn the younger you were when you went blind, he muses; it’s probably easiest if you were born blind – “if it’s something you start learning as you’re crawling around, discovering the world around you”. But it’s something anyone can learn at any age, he believes. It took him just two days to master. And, he adds, it’s something his own brain started learning before he actively tried to learn it.
“I believed for a long time that I could still see,” he says. “I thought I could see shadows and shapes. I didn’t believe I was completely blind – I thought the outlines were still there.”
They were not.
Dewald is completely blind, in the traditional sense of the word, at least. But he can see.
Echolocation is not solely based on sound, you see. It is, without actually using the eyes, the closest one can get to actually seeing. The sounds, it turns out, are actually processed by the visual part of the brain, which explains Dewald’s belief that he was in fact still able to see – when what his brain was actually doing was discovering the area through sound, but processing the information visually. In an experiment where tiny microphones were placed in the ears of blind echolocators as they stood outside and identified various objects such as cars, flagpoles and trees, and their brain activity was measured using functional magnetic resonance imaging, researchers found that a) the blind participants perceived the objects based on the echoes b) they showed activity in the primary visual cortex or V1 and c) when the echolocation recordings were played back to the subjects, the areas of the brain that normally process auditory information were no more activated by sound recordings of outdoor scenes containing echoes than they were by sound recordings of outdoor scenes with the echoes removed.
In other words, the echolocators perceived the echoes as pictures rather than sounds.
So are they pictures? I ask Dewald. Does he see them, then, in his mind?
Not exactly, he says. It’s not exactly like seeing. It’s hard to explain. But he has a clear sense of what he’s locating. He uses the word ‘see’ to describe it.
“Daniel [Kish] always says: if a blind person walks into something, it is no different to a sighted person doing so, because we have just the same capacity to perceive what is around us,” he says.
“I am impatient with myself,” he admits. “I want to do more biking than I do now, for instance. There are no limitations to one’s achievements.”
Kish, 43 and president of World Access for the Blind, went blind at the age of 13 months from retinoblastoma, the same eye cancer that affected the late Canadian musician Jeff Healey. Kish taught himself to echolocate – his parents recall watching him click to himself as a small child – and now he runs workshops all over the world teaching people the same skill. Dewald, based in South Africa, has also passed on what he knows about echolocation to those who want to learn, including a number of children.
“It’s difficult with children,” he admits. “You have to make it fun for them, make it a game.” He has taught children under the age of 10 to echolocate successfully, and believes that despite the challenges, echolocation is a profoundly useful tool that can foster lifelong independence in a blind child – and, of course, the later adult.
Successful echolocators can describe their environment with incredible accuracy – Kish, for instance, once jokingly told off a journalist who visited him for his poor parking skills, having measured accurately, from some way away, the distance between the journalist’s car and the kerb. Men’s Journal put it thus: “Kish is seeking – despite a lack of support from every mainstream blind organisation in America – nothing less than a profound reordering of the way the world views blind people, and the way blind people view the world. He’s tired of being told that the blind are best served by staying close to home, sticking only to memorised routes, and depending on the unreliable benevolence of the sighted to do anything beyond the most routine of tasks. Kish preaches complete and unfettered independence.”
It’s not only the spread of echolocation that is revolutionising the way the blind experience the world – and introducing a more visual experience to the way they perceive it. New technology is developing all the time. The BrainPort, for instance, is a new development that allows blind people to see their surroundings in polygonal and pixel form, via a design that “looks like a lollipop”, as Dewald puts it. A camera picks up images of the surroundings and processes the information via a chip which converts it into impulses that are sent through an electrode array, via the tongue, to the brain. “The tongue is very sensitive,” he explains.
Dewald doesn’t formally hold workshops the way Kish does. At the moment – having used and taught echolocation for five years – he’s focusing on growing his business; the next step is getting a driver, he tells me. But he still wants to spread the skill that has enhanced his perception of the world and he’s more than happy to teach anyone who wants to learn. There are no limitations to blind people anymore, he emphasises.
“There is such amazing stuff happening,” he says.
No limitations? Indeed. DM
* In less good news, Daily Maverick recently received news that the Institute for the Blind in South Africa is facing closure as the department of labour pulls the plug on its funding and Lotto contributions dry up. For more information you can visit http://www.blind-institute.org.za, or @Institute4Blind on Twitter; alternatively www.facebook.com/Institute-for-the-Blind.
Those wishing to learn echolocation can reach Dewald van Deventer at 0824614865.
Human echolocation activates visual parts of the brain on Science blogs.
Magician's tricks are not generally covered by intellectual property laws. They can be stolen and repurposed by anyone.