I seem to have the same issue, As I have bought a new computer and re downloaded arma 3 but now i have no gun sounds from the main player as a unit or gunner in boat or helicopter apart from that the game runs fine specs are intel I7 nvida 2gb graphics 16gb ram and running windows 8 ...

Arma3 crashes data execution prevention shuts the game down on windows Vista .

Any ideas are good, as we have the editor to play around with.
So just let your imagination run wild !!