Part of the problem is that Neverwinter Nights does not get a long with Windows 7. The other part of the problem is that Neverwinter Nights also does not recognize driver sets newer than 2006/2007 ish. I have a similar problem of my audio only playing out of the left channel half the time. NEVER had that problem running windows XP.
I have yet to see, or hear of a fix for neverwinter nights and the audio options.