If we're going to warp this conversation from the first concert I've been to to the loudest concert I've been to, I'd have to say it was The Pretenders an the Oakland Auditorium, sometime in the late '70s. For some reason, they had Ted Nugent's _outdoor_ rig (by TFA Electrosound) stuffed into a 3600 seat auditorium. They had The Clash's engineer mixing.
Now, I've been a sound engineer for years, but that was the only time I actually experienced temporary deafness because the PA was so !@#$%^&* loud. I heard something that may have been Good Evening, Oakland! followed by a blast of what might have been a snare drum, then near-total silence except for a telephone ringer somewhare off in the distance.
Now, I had worked some incredibly loud gigs before (Joe Walsh, blowing up half the PA at Santa Barbara; the Who in Phoenix; and we won't even discuss ELP at the US festival...), but this was a first.
Scared the shit out of me, it did, seeing as I used my ears for my living, at the time. Pissed me off, too, as I really wanted to hear the concert.
I had regained enough hearing to be functional by the next morning, but the ringing didn't go away for almost two weeks. It took about 2 months until I could take a hearing test and get the basically same results I got before the exposure. (I never did get that last 2db at 22Hz back, dammit. Though my upper end stayed at 19.8k, same as always.)
I should never have taught those bozos at TFA how to wire speakers in-phase...