Control over who can use audio output channel in XP

I have a need to turn off other audio sources when I plan to use the Text to Speech API. The other audio may be in another process. I have looked at the mixer control, but I really only have control of the output there. Is there anothe开发者_如何学JAVAr place in XP that I can control the output so only my app is able to be heard?

See http://alvas.net/alvas.audio.aspx