Hunger Games Simulator - How does a mute exactly scream for help?

If Gordon Freeman screams and no one is around, is he still mute?

He isn’t actually mute and neither is Chell.
Chell doesn’t speak because GLaDOS upsets her. (Confirmed by Valve)
Gordon evidently doesn’t have much to say, though he can speak as confirmed by the HL PS2 manual in which it’s mentioned he had a phone call with someone at Black Mesa. He also grunts if injured.