Strange sound issues with SC2 and L4D2

[illogik]

I posted this in the main sound forum, but they suggested that I ask around here, since the problem is confined only to some games. Here's a link to my previous post:
http://www.sevenforums.com/sound-audio/149460-hp-idt-hd-audio-selective-headphones.html#post1283771

To sum it up, my sound works as designed, except when playing SC2 or L4D2. Then, my sound plays through speakers even if I have headphones in. Once I exit SC2 and L4D2, everything goes back to normal. Also, my sound works fine in Dead Space 2, thankfully.

Anyone else have this problem? I've gotten a few replies on the B.net forums, although they haven't been of much help.

EDIT:
Specs as follow:
HP dv5T
Windows 7 Pro 64-bit
Core 2 Duo P8400
Nvidia 9600M GT
3GB RAM
Modded video drivers, latest drivers I can find for everything else

Thanks.

 

[Maguscreed]

manually setting the primary sound device as the windows sound device is the first thing I can think of. I've never heard of a laptop with two output formats, but the behavior you are describing seems to point to that possibly being the case.

 

[illogik]

I've got my primary sound device set to "speakers and dual headphones". They behave as I want them to except when I'm playing SC2 and L4D2, lol. Manually setting my output to independent headphones doesn't work, either, for some reason.

 

[Maguscreed]

If you haven't already yet.
I would suggest removing the roxio studio package from the computer.
The information on this computer says nothing about what audio device it has.

 

[illogik]

I've got a clean install of Win 7 Pro, none of the cruft that HP computers usually come with. Sound hardware is an IDT HD Audio chipset, nothing special aside from the fact that it doesn't seem to work properly, lol.

 

[illogik]

Fixed.

So here was the problem: in playback devices, I had "Speakers and Dual Headphones" set to Default Device, and "Independent Dual Headphones" set to Default Communications Device.

This, for some reason, caused any game with voice chat, to output only voice to the headphones, while putting game sounds through the speakers.

Shuffling around the settings so that I no longer had a Default Communications Device fixed things. "Speakers and Dual Headphones" are still set to Default Device. Everything's peachy now.

For those who are interested:
Right-click on your speaker icon in the system tray, go to Playback Devices, and make sure Default Device is set to what you want, and make sure there is no Default Communications Device setting.

 

[Maguscreed]

I had made the connection that l4d2 was a voice enabled game.
Thanks for posting back to let us know.