I use Avantek earplugs, that are rated at -18 db. They are a knock off of Eargasm, and I got them on Amazon.
The problem with the db meter on the phone is they are not calibrated. The iPhone ones tend to be better as the hardware is more standardized. The android ones, well not so much.
Good luck with it, but I would protect as you already have some hearing loss, and the T should improve if you stop setting it off. I would also keep a pair of muffs handy for a fire drill as they can exceed 100 db, and those musician plugs will only be partially protective for such loud sounds.