Tennis, like golf, is one of those sports that's hard for non-players to appreciate how difficult it is to master. On the other hand, it would be hard for anyone to underestitmate the difficulty of mastering blind tennis:

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…

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…

And for a local angle, here's a quote from a dean at UNCG:

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.”

Be sure to check out the video that accompanies the article.