i used to b heavily into home audio and at one point my system actually cracked the drywall in my house not only in the one room but in another room on the opposit side of the house. and even with all that abuse my hearing seems to still b good.
Firearms is another story tho. would prolly only take a few clips or cylinders to perm damage ur hearing without hearing protection.
Like i said earlier 5 shots from my 44 c&b without protection and my left ear had pain for about 2 hrs after.
"God made man... But sam colt made em equal."