Choppy mic input in Mumble on F11

[Casey Bennett]

The title says it all--I'm having choppy mic input in this one program, 
Mumble, a VoIP program that uses the Speex library, to the point that 
I'm completely incomprehensible. But mic input is fine in all other 
programs, like Audacity. And here's the weird part: The choppiness is 
cured in Mumble whilst Audacity is open and it is recording (or 
recording and paused), but occurs again if I hit stop or close Audacity. 
Anyone have a clue on how to fix this?

I'm using a fresh install of F11, incidentally, and PulseAudio is 
currently handling my audio duties.