WATERTOWN, Mass. — Dan Guilbeault was 3 when doctors discovered a tumor called an optic glioma pressed against his optic nerves. He continued to play the sports he loved — basketball, baseball and football — until he lost most of his sight at 11.
Now he is 19 and almost completely blind, and his favorite sport is tennis.
When he first heard about tennis for the visually impaired, his reaction was “No way!” he said. “I was skeptical.”
So were faculty members at the Perkins School for the Blind here, when a sighted student from nearby Newton proposed it nearly two years ago. But Perkins, known for athletic innovations like adapted fencing, decided to offer what are believed to be the first blind tennis classes in the country.
Like tennis for sighted people, the game requires speedy court coverage and precise shot-making. Blind players rely on their ears to follow a foam ball filled with ball bearings that rattles when it bounces or is struck.
“Your ears have become your eyes,” said Dr. Robert Gotlin, director of orthopedic and sports rehabilitation at Beth Israel Medical Center in New York City.
Sejal Vallabh, a 17-year-old high school junior in Newton, encountered the sport during a summer internship in Tokyo and then proposed the program at Perkins. She set up a volunteer organization, Tennis Serves, which introduced the sport last year at Lighthouse International in New York and the California School for the Blind in Fremont.
As blind tennis grows in the United States, where the Census Bureau estimates that 1.8 million people over 15 have “severe difficulty seeing,” it is testing popular notions of the limitations of blindness.
“I want to show that it is possible for blind athletes to play tennis,” Ms. Vallabh said. No one believes it, she said, “until they see it for themselves.”
The most important adaptation is the ball, which is larger and made of foam, wrapped around a plastic shell that holds the ball bearings.
“It sounds like bells ringing,” said Emmanuel Ford, 10, who has cerebral palsy and is learning to hit tennis balls at Lighthouse.
Other adaptations include a smaller court with a badminton net lowered to the ground, string taped along the lines and junior rackets with oversize heads. Players with some sight get two bounces, the completely blind three. Only one set is played, and an umpire calls the lines.
The first sound-adapted tennis ball was designed in 1984 by Miyoshi Takei, a blind high school student in Japan. Now, about 300 players compete in tournaments there; blind tennis is also played in China, South Korea, Taiwan, Britain and Russia.
During matches, Mr. Takei, a 16-time national champion who worked as a massage therapist for older people, mostly hit flat, aggressive strokes, but lobbed the ball on defense to regain court position. Sometimes he lunged or dived for shots. (He died last year, at 42, after falling in front of a train.)
His widow, Etsuko, who is also blind, said he saw the “court in his mind and he knew where he was standing, where the ball was flying and bouncing.” By listening, she said, “he could control the ball very well.”
An expert on orientation and mobility for the blind, William R. Wiener, dean of graduate studies at the University of North Carolina, Greensboro, said that sound localization “is so important when blind people navigate the world,” and added, “Listening to the ball, locating where it is and swinging at it probably helps you with the sport and also with your mobility.”
Blind tennis is made possible, scientists say, by the adaptability of the human brain — which appears to repurpose its visual area, the occipital cortex, to process sound and touch in response to blindness.
A series of studies discovered activity in the visual cortex when blind test subjects read Braille, and found that a blind woman could no longer make sense of the raised dots after suffering an occipital stroke. Another study, of sighted subjects who were blindfolded, showed that the occipital cortex began processing tactile and auditory information within five days.
“How it works is not a mystery,” said Melvyn A. Goodale, director of the Brain and Mind Institute at the University of Western Ontario. “We know that it is possible to localize sounds, and it is likely that the blind get better at this than sighted people.”
Dr. Goodale and his colleagues are studying how echo processing works in the occipital cortex of blind echolocation experts like Daniel Kish, who as a baby lost his sight to retinoblastoma. Human echolocators use palatal clicks or hand claps to “see” objects around them, like sonar in bats, only bats use ultrasonic frequencies that can resolve flying insects. This skill allows Mr. Kish to hike along cliff edges and ride a mountain bike.
While humans don’t have the auditory resolution to echolocate a moving tennis ball, blind tennis “promotes freedom of movement,” said Mr. Kish, president of World Access for the Blind, a nonprofit group that has taught echolocation and other mobility skills to hundreds around the world. “Most blind kids just don’t get early experience interacting with flying projectiles.”
Kiran Prasad, 20, a Columbia University junior and Tennis Serves coordinator at Lighthouse, said: “They’re living in a world that’s built for sighted people. I can only hope that tennis is giving them that confidence to feel like you can do anything.”
Ms. Vallabh, the young founder of Tennis Serves, hopes to someday host a national tournament and to have blind tennis recognized as an official sport at the Paralympics.
But first the sport has to catch on, and it takes a few years for totally blind players to become proficient enough to play a match, said Ayako Matsui, former secretary general of the Japan Blind Tennis Federation. And it is still met with skepticism. The Washington State School for the Blind rejected Ms. Vallabh’s pitch, said Jennifer Butcher, a fitness instructor there. “But if a student expresses interest in learning tennis, we could try it down the road,” she said.
Meanwhile, Ms. Vallabh is working to improve the sport, partnering with an engineering class at Harvey Mudd College to design a ball that emits a continuous sound, so players can hear its trajectory before it bounces.
At Perkins, a sound-adapted tennis ball sits on the desk of the school president, Steven M. Rothstein, symbolizing possibility.
“Sometimes you don’t know until you try it,” said Matt LaCortiglia, the adapted physical education coordinator at Perkins. “Now we’re doing a lot more tennis.”