Well, I'm completely deaf in one ear and partially in the other due to a shotgun being fired next to me ear when I was a little kid. Muzzle reports don't seem to register to me much more other than just a thump to my chest and that's with the big bores I have shot (aka. .50 BMG and 25mm). However, there's one gun in particular that was a true ear ringer to me. This was back when I was very much into blackpowder revolvers. I had an 1858 Army model with a 12" bbl and my friend had an 1851 Navy model with like a 6" bbl I think it was. My gun came with a 30 grain spout for my flask and my friend's came with a 24 grain spout. We then once switched spouts and WOW!!! His gun was a real ear ringer with them 30 grain charges.