Okay, if ArmA 1 or 2 was to have truly realistic sound, this is what would happen, according to my experience shooting firearms:
After the first shot your ears would ring. With a few more shots, the ringing in your ears would continue and sound would begin to get muffled, almost like you added cotton into your ears.
The U.S. Army protected us against hearing loss by making us wear ear plugs when we went to the qualification range, but when a firefight begins, how many soldiers shout to the enemy, "Wait a minute! I've got to put in my plugs!"