I also find that a lot of theatres are too loud now, but maybe my ears are getting old.

I do too and I’ve probably damaged my hearing in my youth by being careless & invincible. I bought a set of fancy concert earplugs ($30ish) that protect hearing without muffling the sound and they were well worth it. They fit in a little capsule on my keychain so I’ve got them if I wind up someplace unexpectedly loud.