As for shouting down, I'm not a fan either. My first thought isn't to turn to violence, though.
Yes, doing nothing works real well, please stop or I will say please stop again. Not a fan of violence but it someone is being a dick there is usually only one way to make him see the error of his ways and it usually only takes one example for them to learn quickly.
Have some manners, let the person/group speak and then say your piece, not that difficult to do.