There is a whole cottage industry now of in-canal earplugs made of clear or nearly clear material. The better ones have a relatively flat response curve. Etymotic sells some they bill as meant for concert goers (though theirs are not as covert as newer brands).

I have reports from multiple neurodiverse people about how much better they can deal with (loud) social obligations. One person diagnosed with ADHD is practically a different person with their earplugs in.