Does anybody know about sound config?


I am looking for some information on how the sound works on aircraft, in particular what determines the sounds that you hear outside and what is heard inside the cockpit. I am guessing it will be a parameter somewhere in the sound.cfg or in the actual .wav file.
Can anybody shed any light on this please.
Many thanks in advance.

OK, I have that figured out now, but how does the ATC sound work? What defines the sound to come through the headset and not the speakers?

Also, where do the sound files have to go in FSX, and is there an ATC sound config?
Thank you.