Innovation

A twist on tennis allows the blind to play

Find it hard enough to make contact with a tennis ball? Try doing it just based on the sound the ball makes when it hits the ground.

Written by Laura Shin, Contributor June 10, 2012 at 9:14 p.m. PT

Tennis for the blind seems like a fantastical notion. After all, when sighted people have a hard enough time making contact with a little ball that's whizzing through the air, how could a blind person be expected to do so without the benefit of sight?

But a new kind of tennis ball filled with ball bearings that rattle every time it hits the ground or a racket is making it possible for the blind to play.

The origins of blind tennis

Blind tennis originated in Japan in 1984 with a blind high school student named Miyoshi Takei. According to The New York Times, "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.'" (Takei died last year at 42 when he fell in front of a train.) Japan now has about 300 players who compete in tournaments, and the sport is also played in China, South Korea, Taiwan, Britain and Russia.

American high school student Sejal Vallabh, who is sighted, learned of the game while on an internship in Japan. The 17-year-old native of Newton, Mass., founded a volunteer organization called Tennis Serves that is starting to introduce blind tennis to the U.S., where about 1.8 million Americans over 15 have “severe difficulty seeing," according to the Census Bureau.

Tennis Serves has brought the game to the Perkins School for the Blind in Watertown, Mass., Lighthouse International in New York and the California School for the Blind in Fremont. Vallabh hopes to someday hold a national tournament and to have blind tennis recognized as an official sport at the Paralympics. She is also working with an engineering class at Harvey Mudd College to design a ball that emits a continuous sound, so players can hear the ball as it travels through the air, even before it bounces.

How blind tennis differs from sighted tennis

The ball is larger than a regular tennis ball and made of foam that encases a plastic shell holding the ball bearings. (You can hear the sound it makes in the video below.)

The game is also played on a smaller court with a badminton net lowered to the ground, with junior rackets with oversize heads and string taped along the lines. "Players with some sight get two bounces, the completely blind get three," the Times says.

How the mind adapts to play blind tennis

One of the key adaptations of blind people is their ability to localize sound. In the blind, the human brain seems to use the area usually devoted to vision, the occipital cortex, to instead process sound and touch in order to help them "see" what is around them.

For instance, studies show that when blind subjects read Braille, their visual cortex activates, and that, in sighted people who are blindfolded, the visual cortex begins to process sound and touch within five days.

So, when it comes to blind tennis, the players' ability to localize sound is key to their ability to find and make contact with the ball. The Times quotes William R. Wiener, an expert on orientation and mobility for the blind, who is dean of graduate studies at the University of North Carolina, Greensboro, on the importance of sound localization to the blind: “Listening to the ball, locating where it is and swinging at it probably helps you with the sport and also with your mobility.”

Still, it takes a few years for totally blind players to be able to play a match of blind tennis, according to Ayako Matsui, former secretary general of the Japan Blind Tennis Federation.

But sound localization isn't the only sound processing skill that enables blind players to see. Some of the blind use echolocation to navigate the world -- in other words, they use palatal clicks or hand claps to "see" objects around them the way bats use sonar. For instance, Daniel Kish, who lost his sight as a baby, uses echolocation to hike along cliff edges and ride a mountain bike.

Watch the video below to see a blind tennis tournament.