I’m watching the English Open final and noticed that a lot of the people in the audience wear a an ear piece. What is it connected too? The referee’s mic? The TV live commentary? Something different?
Live commentary.
I suspect the audience must remain quiet.
Oh yes, quietness in the audience during play is crucial! You can get kicked out for making noise or letting your phone ring.
… and swift ejection for a particularly noisy series of farts. 
That’s, of course, the worst. 
There was one time that a commentator made a joke that was funny enough to cause multiple people to laugh at once and the player who was taking his shot got (mock) angry at the commentary box because even though he couldn’t hear it he knew they were responsible
That’s really funny! 
I thought it was; breathe in … breathe out … breathe in … Cue an old “blonde” joke.