At various times I have been...privileged to be in the presence of a .380 ACP (mine, liked it, wish I still had it), a .38 SPL and a .45ACP (other peoples') and a 155mm howitzer (Uncle Sam's; I was about 50 feet away), without ear protection when they were fired. The .380 was an experiment on my part that I resolved not to repeat; the remainder were surprises.
lost most of muh hearin' in the right ear to an 8" SP Howitzer in the fight at Um Hujul... 8" in direct fire is devastatin' but definitely a last resort... still, we didn't havetuh engage dismounts... they wuz scattered all over the desert floor...
now I got tinitus in both ears... funny how I can look you in the eye at 10' and not unnerstnd yuh sometimes, but I can hear a deer walkin' in the woods at 100 yds in a high wind...
Times have sure changed, I shot on the Knights of Columbus rifle team in high school, in a basement range, .22 rifle. Ear protection? What's that.