Goalball is a Paralympic sport played by athletes who are blind and visually impaired.  A cross between soccer and team handball, goalball is played on a volleyball sized court with tactile markings.  Three players from each team play on opposite sides of the court with the object being to throw a ball with bells in it past the opposing team and into the 9 meter goal.  Because all players wear blindfolds so players with different vision classifications   compete on an even field, the tactile court markings enable the players to maintain orientation and the bells allow the players to track and block the ball by throwing their bodies in front of it.  At the elite level, the ball can be thrown at speeds of 30 mph  or more and cross the court in under a second.  During the game, the gym must be silent to enable to players to concentrate and react instantly to the ball.