The space before the blind man was a riddle he needed to solve. Was he facing a house, a car, a hedge, a fence, a tree or open space?
Ryo Hirosawa pushed the tip of his tongue hard to his palate, and made a sharp click.
He tried to focus on the form and timing of the click's echo as it came back to his ears, as fast as a blink.
But he couldn't quite decipher the shape of the sound. Was is scattered, as if it hit foliage? Was it a clean pulse ricocheting off a stucco wall? Was it hitting multiple objects and coming back in fragments, milliseconds apart?
"Are there solid objects in here or are there sparse objects in here?" asked his instructor, Brian Bushway.
Hirosawa kept clicking, and edges in the acoustic landscape gradually began to emerge as a faint picture.
"There is a tree, I think, here, which is tall, and I see a house behind," Hirosawa said.
They stepped into the yard to find out whether he was right. Bushway tapped his cane against the tree trunk and reached up to grab a branch and shake the leaves. "Sparse objects," he said. "Feel it, know what it sounds like."
He knocked the wood panel of a wall.
"A house," Bushway said. "Awesome, very good."
This quiet cul-de-sac of old bungalows in Long Beach is at the center of an unorthodox movement to teach blind people to navigate using tongue clicks for orientation.
Daniel Kish, 49, lives and runs World Access for the Blind here, with Bushway as one of his two main instructors.
Their students learn to better perceive the space before them, sending out sonar, like dolphins or bats, to get an acoustic read on their surroundings — a human form of echolocation.
Kish has worked with numerous scientists to study how the brain accomplishes this. A brain imaging study on Kish and Bushway by researchers at the University of Western Ontario found that when they were echolocating they were processing acoustic information in the spatial-visual part of the brain, not the part normally associated with hearing.
On this recent morning, Kish had just returned from giving a TED talk in Vancouver and was working on a textbook about this technique, which he calls flash sonar.
Kish had retinal cancer when he was born, and lost both eyes soon after his first birthday. He unconsciously began making clicking noises with his tongue to navigate, as other blind children often do. But unlike many other parents, who worried that their child might be ostracized for sounding weird, his mother and father didn't discourage him from clicking, and let him roam the neighborhood in Placentia like any other 1970s kid.
He rode bikes, climbed trees and delivered his mother's Avon catalogs to neighbors near and far. He didn't understand how the clicking was helping him until he was 11, when a friend pointed out that he was doing what bats do.
"I hadn't thought about it," he said. "I was just a squirrelly kid who liked to be active."
Bushway is pure Southern California: shaggy and casual, at home in shorts; enjoys a nice Mexican beer at lunch. He lost his eyesight from optic nerve atrophy in the eighth grade. But walking through school in Mission Viejo, he could still see columns in the hallway, even count them. He was baffled. He closed his eyes and they were still there.
When he met Kish in 1996 at a pancake breakfast at the Braille Institute in Anaheim, he told him about this phenomenon. Kish concluded his brain was forming a spatial image from the ambient sound reflecting off and sluicing through the columns.
"I was imaging acoustically," Bushway, 32, said. "The brain creates images whether you send it patterns of light or patterns of sound."
Kish, by then a mobility and orientation instructor, started working with him to process those sounds, but also taught him to use the click when the ambient sound didn't offer enough information.
Bushway, who had loved to play ice hockey and mountain bike, was inspired to see Kish breaking through the barriers that he was terrified would cage him in.
"Wow, this guy lives his life independently," Bushway recalled thinking. "He does all these fun activities. He could ride a bike. He likes walking and exploring neighborhoods and playing laser tag."
Kish showed Bushway how to skateboard, using a long cane to read the road surface and curbs, and clicking to spot parked cars, intersections and turns ahead.
With the help of another instructor, Andy Griffin, who could see, they started mountain-biking trails and fire roads in the Santa Ana Mountains.
Griffin would lead, with zip ties around his spokes to send out a blizzard of clicks. Kish and Bushway would follow making their own clicks to locate larger objects such as trees and boulders.
In this sonic caravan, they could charge over roots, ruts and rocks as speedily as most mountain bikers — with a few more scrapes to show.
In 2001, Kish established World Access for the Blind to teach the clicking technique. Since then, his team has traveled to more than 34 countries. Kish's other instructor, Juan Ruiz, won a Guinness World Record for the "Fastest 10 obstacle slalom on bicycle — blindfolded." He rode 66 feet with the obstacles placed at random in 25.43 seconds.
They began getting news coverage around the world. Ripley's Believe It or Not! and many media organizations called Kish a "real life Batman."
Kish's high profile drew some criticism within the world of blind advocacy. The main complaint was that the clicking would seem off-putting to the public, leading to further stigmatization. Another was that all the "batman" hoopla reinforced a misconception that blind people have mysterious powers.
The National Federation of the Blind is neutral on Kish's work. "All blind people use echolocation to an extent," said Chris Danielson, a spokesman for the federation. "Mr. Kish has a unique way of doing it that seems to work for him and others."
He said many blind people tap their canes for a similar effect in certain circumstances.
Kish says the click is more effective because it is directional, and doesn't change with the surface of the ground or the angle of the cane.
Brandon Shin, 17, of Hancock Park came to Kish for help two years ago after slowly losing his sight. His father was extremely dubious, suspecting a snake oil salesman. But Shin says he "harangued" his parents so much, they let him have lessons.
Now he clicks all the time, and recently hiked Runyon Canyon by himself. "Just the cane and my clicking," he said.
He says some kids at school made fun of him. "Oh, are you using that weird African language with the tongue clicking?" one snickered, he said. But others have been genuinely fascinated with it.
His father, Mike Shin, says his own skepticism has faded as he's watched his son maneuver around obstacles as though he could see them.
"Sonar has given Brandon self-esteem and courage," he said. "From a parent's point of view, we're worried he'll get hurt. But we're proud. He's doing it better than we expected."
In Long Beach, Hirosawa was still struggling to catch the fast-fleeting echo. If he stood five feet from a wall, the echo followed his click in less than 1/100th of a second.
Bushway knows it's difficult.
"So the hierarchy is, visual information is the loudest, then tactile information, then acoustic information," he explained. "So we're asking the brain to really start paying attention to really subtle stimuli in the environment."
Hirosawa came to Long Beach from a small village near Fukuoka in Japan for hours of personal training. It was his second trip here.
At home, he said, his parents lock him in the house because they are so concerned for his safety. He said blind people in his country aren't autonomous. He sneaked out when he could, but the main path into town follows a river, and he fell in several times.
He and Bushway walked and crossed a busier street and turned back, aiming their clicks to the corner. The echo was sharp, almost metallic.
"There is a house," Hirosawa said. "The surface is really smooth."
Bushway told him to take note of the unique echo from that house, so when he was walking back he would know to turn down that lane to reach Kish's bungalow. "That's a great acoustic landmark there."
Hirosawa kept clicking, taking in the distinctiveness of the sound.
The next time he sneaked out of his parents' house, he would listen for similar spots. And he'd have sonic breadcrumbs to lead him back home.