Originally Posted by SystemaEncephale
That's really interesting and a valid point. I didn't consider the effect of adrenaline.
Check out Lt. Col. Dave Grossman's book, 'On Combat'.
I don't agree with everything he writes, but it's a good book, full of data about that very subject, namely, altered senses during high-stress combat situations.
As far as shooting without hearing protection in other situations - keep it up and you definitely won't need to worry about, because you will lose your hearing, whether you're shooting a 9mm, .45, or .300 Win Mag.