How a blind football match works

1. Each side has four outfield players and a goalkeeper. The outfield players wear eyeshades; the goalkeeper may be sighted.
2. The ball makes a noise, and kickboards along the sides keep it in play. The crowd stays silent while the ball is in play.
3. Three voices guide each team: the goalkeeper in defence, the coach in midfield and a guide behind the goal being attacked. A player going for the ball must call "voy".
4. As in football, the team with more goals wins. Drawn knockout games go to kicks from the penalty mark.

How long

Two halves of 20 minutes, on a clock that stops at every stoppage.