Yeah, this is something I'd be interested in also. My friend downloaded and installed this game on the weekend and he has a problem much like what you describe. Audio playback lasts for about 1 to 2 seconds and then just stops. Sound effects for weapons and combat sound a little odd too.
The music is ok though.
I probably should get him to post his DxDiag file in the tech forum if he's overly interested in playing. He was just checking it out but didn't seem overly impressed with all the glitches in the tutorial. He's running Vista.
I have no problems with audio but I'm running XP.