Disable audio through speakers when using USB headphones

[Guest ckdubois]

Hey all-

I just got a T-Mobile Shadow (but figure this might be a universal WM6.0 issue, hence posting in General Discussion) and really like it so far, however I've discovered one problem. I listen to streaming audio on my phone using the included usb headphones when I'm at work since our work computers are blocked from the internet (annoying, I know). I leave the phone on vibrate mode, and everything goes fine until I get either a text message or a notification of a Gmail email. At that point the sound coming out of the headphones becomes quieter and all of a sudden sound starts coming out of the main speaker for about 2 seconds. I've tested this on normal, vibrate, and silent mode and the same thing always happens. Is there anyway to disable this? What I want is, if I'm in vibrate mode, to have my phone vibrate when I get a email or text notification but keep the music I'm listening to going only to the speakers.

I've read something about this having something to do with Voice Commands, specifically announcements, but I've turned everything I can see to "off" and still haven't resolved it. Is there a way to completely disable the Voice Commands program from running at all?