There are only six players on court at any one time, three for each team. All wear eyeshades with eye pads underneath to make absolutely sure no-one with residual vision has an advantage. Touch your eyeshades at the wrong time during a game and you face a penalty. Audio is all important and the crowd must keep absolutely silent while play is in progress.
In the early evening it's the turn of Team GB's women. I study tactics, as best I can. GB talk a lot between themselves to buoy spirits: "come on girls", "all of it", "wrap it up" - technical terms, I assume. The Chinese women don't speak. Is this also a tactic? If your opponents speak, they've pulled off their metaphorical invisibility cloak and this must make it easier for their rivals. With no speaking and no eye contact, the Chinese women communicate positions and tactics by gently tapping their palms on the floor. It wasn't like this at school.
The court has raised lines and the players reorientate themselves by going to the goal on the back wall to properly line themselves up in front of their opponents.
"I thought the silence was amazing and it was fascinating the way the athletes felt their way across the court," says Sue Lee, a retired teacher from Chelmsford.
The women lose seven goals to one and will play Finland on Friday. I'll be attending as it seems the Copper Box might lay on a commentator so I can use that audio description gizmo and enjoy the match a bit more.