I have never really thought about it, but people who are blind cannot play catch or any other physical activity that involves seeing a object coming towards them. Without seeing the ball one would be hard pressed to know what direction it was coming from or to chase after it when it rolls away.
Three undergraduates at John Hopkins University have come up with a solution. They have designed an audible basketball and backboard system. The ball gives off an audible tone so that direction can be determined. The backboard also emits sound. While the system is still being perfected, there is interest within the blind community. There are many benefits to playing sports and hand-eye coordination is a basic skill that children need. When the system is perfected, it will open up a whole new area for the blind. It may also be adapted for other sports which use balls such as volleyball and soccer.
The students who invented the system are Alissa Burkholder, Ashanna Randall, and Steve Garber. Both Alissa and Ashanna are engineering undergrads and play for the basketball team. Steve Gerber is a mechanical engineer major.