It’s your best friend’s ‘special anniversary’ and she’s arranged a meal, a concert and a hotel for a group of 10 friends. How lovely!
You told her you liked the previous concert, so she has no reason to think you won’t enjoy this. She probably thinks that warning you about taking ear plugs will solve the difficulties you encounter, as you have not told her otherwise.
It’s a shame you haven’t told her your true feelings, however what’s done is done!
She may well be hurt if you decline to go and others may also follow suit, preferring to stay in the hotel with you, leaving her with a very half hearted special celebration!
I would go this time but make it clear as someone else suggested, that you really are not enjoying these concerts as much as you used to and ask her to please not buy any more concert tickets for you in future with out checking with you first.
You can buy silicone earplugs that mould to the shape of your outer ear which really do block out the majority of the noise including building work and drilling etc and are even water tight, so I’m wondering if you just don’t enjoy it, rather than it being solely a problem with your ears and loud noise? I’m wondering if your husband is also putting pressure on you, not to go?
I’m all for honesty, however I would pick your time and a special celebration may not be the best time. I speak from experience as we fell out with one of my closest friends of nearly 30 years over a special occasion and we haven’t been able to rekindle our relationship since!
Good luck, whatever you choose. Please let us know how it goes?