This inability to really participate in the conversation is starting to frustrate her a little, not least of all because if she was talking, she'd like to think she'd have something less ridiculous and dismissive to say.

Well, just because she can't talk doesn't mean she has to be silent. Opening her mouth, she lets out a low, rhythmic howl, pitched to sound very much like: 'blah, blah, blah.' Except she can't really do 'b' sounds, so it comes out more like, "Wrah, wrah, wraaoh." That's how you sound, Andrew.