June 26, 2011 -- In recent decades, a number of blind people have developed a bat-like method of determining their surroundings using tongue clicks. Following recent success in Berlin, the technique could become more widespread in Germany. Some even use "flash sonar" to ride bikes and go hiking in the mountains.
Two-and-a-half-year-old Juli merrily twirls around, holding a small white cane in her outstretched arm. Every so often, she makes a discreet clicking sound with her tongue. Doing so allows her to see with her ears, her parents say. She just needs more practice.
Four-and-a-half-year-old Frida already knows how it works. If someone holds out a pot lid at arm's length, she can locate it with a fair degree of precision. Using subtle tongue clicks, she scans the space in front of her face. "There it is!" she says. With a few more clicks, she can even determine the contours of the lid. The edge lies where the echo cuts off and she no longer hears a response.
The two girls are learning a method of echolocation known as "flash sonar," which resembles the type of active sonar used by bats. Both were born blind in Berlin, and both have parents who want to spare them from the typical life of a blind person.
"We spent a long time looking for a good replacement for vision," says Steffen Zimmermann, Juli's father. He believes that using flash sonar, blind people can get through life with a surprising degree of independence.
Mountain Biking Blind
This April two Americans came to Berlin to train Juli and Frida in flash sonar. They toured the city together, had them perform some initial exercises and explained to their parents what seeing with the ears is all about. One of the most important things is making the right sound: a snappy, dry click is best for locating things in the immediate vicinity.
Bats navigate in a similar way. Using only echoes, they can flutter through thick foliage without incident, plucking insects off leaves with precision as they fly by. Though humans don't hear nearly as well, with a little effort they can make a surprising amount of progress with a similar technique.
One of the trainers is Juan Ruiz, a well-known flash-sonar expert. In several YouTube videos he can be seen riding a mountain bike through rough terrain.
Indeed, before making his way to Berlin, Ruiz made a stop in Italy, where he set a new Guinness World Record. A television studio in Milan was outfitted with an obstacle course featuring 10 columns, spread out over a 20-meter (66-foot) path. The cameras rolling, Ruiz mounted his bicycle and pedaled away, constantly clicking. The spellbound audience followed Ruiz's progress as he navigated his way forward guided by what seemed like a sleepwalker's instincts. One column after the next seemed to enter his field of vision. He curved to the left and to the right and, after 48.34 seconds, rolled over the finish line without a single mistake.
Measuring with Sound
Ruiz believes that anyone can learn to do what he does, including his young students in Berlin, Juli Schweizer and Frida Capellmann. "The girls are already doing quite well for their age," he says.
Juli, the youngest, lumbers fearlessly through her parents' apartment. For now, her discovery of the world of echoes is largely based on games. Her parents occasionally encourage her to use tongue clicks to detect a post or a ball, though it doesn't always work.
But Frida has aready become quite good at the method, her mother says. When she recently asked about an object they were passing in the city, Frida clicked a few times and answered: "Ah, a wall." When they were in a cemetery, she asked Frida to locate a rain barrel three meters away. Frida walked up to it, reached out her hand and patted the water. Another time Frida paused in front of a tree, clicking from the bottom up, tilting her head back as if she were taking a measurement. "How tall it is!" she exclaimed.
Even before the flash-sonar training, Frida had discovered the phenomenon of echoes. When she was crawling, she would slap her hands down on the floor and listen for reverberations. Later on, she made a habit of using a sharp, crow-like call to gauge her surroundings, whether in stairways, subway stations or stores. Since her training started, she prefers the tongue-clicking to the calls because it produces subtler echoes. Now other people's apartments have suddenly become exciting. "The first thing she does is check everything out," her mother says.
New to Germany
Ruiz, the flash-sonar trainer, was also a novice at one point. He learned the technique from Daniel Kish, a California native and pioneer in echolocation for the blind. As a young man, Kish climbed steep mountain trails alone, guided only by a walking stick and the echoes bouncing off his surroundings in response to his clicks. He learned to recognize shrubs, overhanging rocks, fences and sign posts (whose carved words he could then read with his fingers). His resourcefulness has already been documented by numerous television crews, and he goes by the nickname "Batman."
In recent years, Daniel Kish has taken on several assistants, most of whom are former students who now work as certified teachers for the blind. "So far, we have instructed 500 blind people and 5,000 teachers in 18 countries," Kish says.
Two years ago Kish spent a couple days working with then 7-year-old Lucas Murray in the southwestern British county of Dorset. Today, despite his blindness, Lucas enjoys playing basketball. The echoes tell him where the hoop is.
Other assignments have led Kish and his assistants to Mexico, France, Switzerland and Berlin. "Despite searching for a long time, we had never been able to find anyone teaching the method in Germany," says Steffen Zimmermann, Juli's father. Flash sonar is new to the country.
Before now, blind people were generally confined to the narrow circle tapped out by their white canes. But echoes expand the radius of this circle many times over. Loud clicking can yield signals from a building as far as 100 meters away. A parked car can be detected from five meters away. A large train station can be sounded out with a few good clicks in several directions. Someone well-practiced in flash sonar can locate the entrance to the tracks and the kiosks selling juice. The remote sensing technique is perfectly suited for unknown terrain.
Searching for Alternatives Some eighteen months ago, Juli's parents received test results that confirmed that their daughter was permanently blind due to a genetic defect. They can still remember how horrified they were at that time -- less by the blindness itself than the fate that, in their view, awaits many of the blind. They imagined their daughter slouched over the arm of a guide one day, perhaps on her way to a school for the blind, where most children like her are separated from others. Her father then went searching for alternatives. "When I found out about Daniel Kish on the Internet, it was clear that he was our man," Zimmermann says.
Frida's parents were also quickly convinced. Now the two families want to turn others on to this kind of training for the blind, and are working to found an association called "Anderes Sehen," or "Another Way of Seeing." The plan is now to have Frida and Juli learn everything they need from the very beginning and not just the most basic skills.
With their curiosity and love of movement, children of their age learn quickly. Juli is an active child with a sprightly tongue. "Juli talks practically nonstop," says her mother Ellen Schweizer.
She walks up to the table holding a book, touching the paper and smiling with a satisfied look on her face. "Nini Naseweis," she says. Her fingers tell her exactly which one of her roughly 50 children's books this is. "Juli can tell them all apart. And she knows what's inside, too," says her father. Perhaps because of all the reading her parents do with her, she has become a bit of a bookworm. Early on they worked to strengthen Juli's imagination, filling her mind with stories.
Her world is rich in words in other ways as well. She collects them from all over and loves the hardest and rarest ones most. "Baby phase" is one of her favorites, and -- though she might not understand what she's saying -- she can recite entire verses from one of her father's poetry books. During a recent trip to the pediatrician, her parents showed her something new. "Look," they said, "a stethoscope." But, using the correct German genitive grammatical structure she corrected them, saying: "Frau Hübschmann-Mehl's stethoscope."
"Children who can see beam at their parents to get a smile in return," says Juli's father. "But Juli loves to use words to make us laugh."
'H' for Helpless
When Juli plays outside, she is just like all the other kids. She steers her training bicycle fearlessly past posts, dogs and bicycles parked at an angle, chattering away the whole time. Her parents make a big effort not to appear anxious. Juli is supposed to learn how to find her way by herself. She is allowed to play around on chairs and to climb rope ladders on playgrounds. "One bump on the head won't kill you," her father says. He and his wife only allow themselves to warn her when she is in real danger. Doing so is the only way to make sure that Juli learns to deal with the frightening things that can happen in the real world.
But this isn't how the story usually goes. An official has already stamped her identification card with an "H" for "helpless person." For most blind people, this designation is the start of a very limited existence. There is school, and later work -- and the way back and forth that they learn by heart. After the bus stop take 120 steps to the left past the houses, then cross the street and take a right at the cobblestones.
Traditional German bureaucrats have a hard time figuring out how to deal with blind people who venture off into the wildnerness by themselves. They can easily dismiss people like Daniel Kish -- with his "Batman" nickname and "No limits" motto -- as a wonder boy, a strange talent bordering on the supernatural. In Germany, there has long been a friendly disinterest in flash sonar. It's a useful skill if someone can master it, they say, but what good is it to the average blind person?
Take the example of Reiner Delgado, a social worker at the German federation for the blind and visually impaired. Delgado also uses a type of spatial hearing. When he plays blind soccer, he can detect the wall surrounding the pitch from 20 meters away. When he leaves home, he snaps his fingers every so often to determine the position of the surrounding high-rises. Even so, before embracing the type of flash sonar that Kish champions, Delgado wants more proof. "We need a proper study with a larger number of test subjects," he says. "Then we'll be able to see whether everyone can really learn it."
Clicking Unpopular with Students
Still, numerous attempts have already shown that even blindfolded people without visual impediments can learn to detect objects in their surroundings after just a short period of time. In fact, lacking any instructions, some blind people have simply taught themselves the technique. Dave Janischak, a 15-year-old high school student in the western German city of Marburg, stumbled upon a type of flash sonar when he was four. At the time, he attended a day care center with a mentally disabled boy who spent the whole day clicking his tongue. In what began as childish teasing, Janischak mimicked the boy's clicking. But he quickly discovered that doing so helped him get a reading of his surroundings. "I suddenly knew where the doors were," he says, "and whether they were open or shut."
For people who can see, the sense of perception is dominated by vision. In fact, over the course of evolution, our hearing has grown to assume a subordinate role, concentrating on things that make noises themselves -- on the hungry jaguar creeping through the underbrush or the guest at the loud party calling out from across the room. But when it comes to sound-based orientation, echoes can be misleading.
"For this reason, the brains of people who can see tend to suppress the spatial echo," says Lutz Wiegrebe, a Munich-based neurobiologist. "It is automatically canceled out as mere background noise." But he adds that the information is not lost. "You can quickly learn how to make use of it," he says. "For blind people, that would definitely make sense."
Indeed, most blind people intuitively know a little about how echolocation works. Some hit the sidewalk with a cane as they walk in order to locate a doorway; others snap their fingers when they enter someone else's bathroom to locate the sink, which returns a hollow echo. But hitting a stick on various surfaces returns a different sound each time. And snaps of the finger take place at varying distances from the ear -- and the brain processes them differently each time as a result.
Only tongue clicks allow precise spatial impressions. Mouth and ears practically form a single unit, and with increasing practice, their collaboration becomes automatic. Still, many blind people find the clicking unpleasant at first. Reinhard Eiler, who teaches blind students in Marburg, often encourages them to try it, with limited success. Blind people live in constant fear of attracting attention, he explains. Since they can't see who's staring at them, they easily assume the worst.
School Signals Interest
This meekness often starts early in life. Many blind children rarely leave the house. When they do, they tend to remain at their parents' side holding hands. "That's totally wrong," says Eiler. "They just shut down. Unfortunately, many kids are still growing up overprotected."
For some time, education experts in Germany have been discussing whether the clicking method could be helpful if learned at an early age. So far there have been no results. "But if parents also start asking for it now, the situation will obviously change," Eiler says.
Does that mean that the ideas of Daniel Kish could gain traction in German schools for the blind? Will teachers here start to receive instruction in flash sonar? "Definitely, yes," answers Jürgen Nagel, the head of the teacher-training department at Blista, the German school for the blind established in Marburg almost a century ago. Nagel sent someone to observe the training given to the blind girls in Berlin, and he was deeply impressed.
For now Juli and Frida will practice flash sonar with their parents. With her inquiring mind, Frida has already made rapid progress. And even Juli, the much younger of the two, can occasionally be heard making tongue clicks by herself. She also likes the word "click."
For example, when she's riding her trainer bike, Juli knows she can identify objects in her path. But, of course, there's always a lot going on when she's moving, and she likes to comment. Suddenly she hits a pole, which interrupts her constant chatter only for a brief, frightful second. "Oh," Juli shouts, "I forgot to click again!"
Translated from the German by Josh Ward