My thoughts exactly, as BwickFS39 said above. If you're shot even by a battleship-mounted rail gun, you don't hear your impending doom until you're already long dead. The projectiles of most high-energy weapons (I'm counting sniper rifles here for the most part) travel faster than sound so there's a delay for the "bang" and the bullet hitting you, or close to you. AFAIK, ArmA II simulates the delay just fine. Haven't tested it but it looked like it was so when I observed someone shooting zombies in a pinch.