As far as i noticed i am not the only one with that specific problem in the "FrostBite Passage", i've read it in other postings here too.
So i think that must be somekind of special bug and it has nothing to do with the sound. I tried that "sound-fix", but it didn't help.
My system:
Win7 64 Bit
E6600 @ 2.8
4 GB RAM
NVIDIA GTX460 (latest beta-drivers)
Soundblaster Card