From what I can tell, it checks to see if you have the localized Voice Overs of your set language. If you do, it sets the Audio Language to your language. If not, then it sets it to the US version. Going to try uninstalling and re-installing into German since I can't do much testing without a foreign game install.
EDIT:
Ahh, only the English and Russian versions available now, I see. Going to try out the Russian one, though I haven't a clue if they have voice-overs.