Just a not-so-quick revisit about the notion of having some tactical advantage, if you've been previously exposed to muzzle blast as a shooter, without hearing protection.
I have to remind myself that many people have never heard a gunshot while without ear protection, so this whole topic might be a bit mysterious for some. It's funny to me that during the times I've introduced new people to shooting, they sometimes want to take their protection off to hear a shot, as a bystander. It seems they simply want to experience the sound once because they're inquisitive. They wonder about things like the level of sound, how much the air muffs/plugs really do, etc, etc. I tell them that's fine but make them stand back a safe distance appropriate to the gun being fired. Needless to say the new shooters are mightily impressed and surprised at the volume of the sound and quickly, with wide eyes, put their muffs back on! Initially I always get a kick and a chuckle from this because it reminds me of the things I take for granted as a very experienced shooter. I was so young the last time that I consciously wondered about such a thing that it's difficult for me to remember what that was like.
Since that time I've experience so many unprotected shots as a shooter while hunting, as a bystander from tens of yards away, and to 3 really bad accidental discharges in enclosed spaces. None were mine by the way, but I was unfortunately exposed to the sound. Now when I hunt with a firearm I always try my best to either wear hearing protection, as in hunting foul, or put on hearing protection before a single shot, as in large game hunting. I guess you could say I "wised up" to the idea of hunting with ear protection but it wasn't a hot topic for hunters 25 year ago. Today we know better.
Since I've experienced unprotected shots either through ignorance or accident I can say definitively that there is no reason as a shooter to intentionally expose yourself to the blast, unless of course it occurs during the actual act of self defense. When you're the shooter and expecting the sonic impulse of the gun upon firing, it's rather easy to deal with mentally. This is what I'd refer to as to hunter's shot. Since you're doing the shooting, it's loud but comes as no surprise. Likewise is the case if others around you who are also shooting but you're expecting it, as in the case of foul hunting where you'd be separated by 15-50 yards. When it comes to the issue of "tactical advantage" it has much more to do with the expectation of the shot than the sound itself. During an actual event, the sound goes pretty much unnoticed and that's even the case for the hunter. It does nothing to effect them at the time of the shot but perhaps after all the excitement is over they might notice some ringing in their ears or temporary deafness depending on the caliber and environment around them.
The unprotected shot only ranges from shocking to petrifying when you're not expecting it, which is made exponentially worse if your in an enclosed space and it was presupposed there would be no shot. Those are terrible and it wouldn't matter how many times you tried to build up a tolerance for something like that it would help any. I was once in a 8 x 8 foot tile bathroom when a officers length .45 was discharged and I lost most of my fine hearing for a good 12 hours. Undoubtedly some long term damage was done. If you were exposed to that every day, you'd never get used to it but would go deaf in short time.
In any case, if a new shooter is simply inquisitive about the sonic blast of certain guns then let someone else who is protected, fire it while outdoors, while you stand back, directly behind them a good 7 yards and double the distance with centerfire rifles. It's still not good for the ears but it will let you satisfy your questions with minimal harm. Another way would be to visit a local trap and skeet club. You can experience a lot of unprotected shots while standing back 25 or 30 yards. If it gets uncomfortable, move further away or put on your protection.
Not sure if that helps anyone but I hate to leave my unmentioned thoughts hanging.