Danni,

          If by "shut off the chatter" you mean to stop NVDA from speaking while you type, etc., you can use NVDA Key+S to toggle speech mode.  I also use the No Beeps Speech Mode NVDA add-on so that I either have speech or silence, as there is a third feedback using beeps which I have no use for.  The NVDA Key+S is a true on/off toggle for speech if you use that add-on, otherwise it is a cycling switch between, off, beep mode, and speech mode.
--
Brian

I worry a lot. . . I worry that no matter how cynical you become it's never enough to keep up.