I've shot a few thousand rounds. 9mm is very loud. Shoot it in a closed space just once without earpro and you will cause permanent damage to your hearing.
I don't think a million round sample size would help you in judging this.
You realize it's a function of distance and that function is logarithmic, right? A gunshot at one foot is a hundred times louder than it is at 20 feet. If you were exposed to a million gunshots of any caliber from a foot away, you would be profoundly deaf.
So why even mention your million rounds as a reply to "I just fired a gun right next to your head, neither of us was wearing ear protection and now we’re having a conversation at normal volume"? Talk about ignorant.
My point still stands. I've had 9mm from an m17 shot beside my head and had zero issues with my hearing afterwards.
Edit to reply to your ignorant use of the word ignorant:
I have personal and professional experience with many different things that shoot, so calling my response ignorant is just wrong. That's like people saying "I literally just died" when what they really meant was "I'm a little embarassed"
Think it just varies by rounds/gun and surroundings. I've had 9mm's be quite quiet, but I had a Walther PK380 that would make my ears ring in a field without protection. It's a smaller round than a 9mm... So never understood why.
Believe it or not when I took my concealed weapons license class years ago it was in a small room indoors, at the end to ensure everyone has at least had fired a gun before, they handed us an old .22 handgun (maybe a browning? Long time ago) with a silencer on it. And 1 by 1 had us take shots at a small target with a sack of what I assume was dirt/corn/or such behind it.
So around 15 people in a 10 by 30 foot (3.3 by 10 meter) room where we shot at a target with the other 14 people standing behind us. No hearing protection was needed. It obviously is louder than the movies, but amazing to not have our ears ringing in a space so small.
The silencer on such a small handgun is awkward at best. Your natural instinct is to want to hold it up, as it weighs down the front of the gun drastically, but clearly you should/can not fire like that, as the gases will expell throughout the silencer resulting in injury more than likely. That was in Florida, the state which concealed weapons permit is accepted in the most U.S. states during travel. The class, took no more than a couple hours during a single night.