Hi all, A bit confused by ear plug ratings. I have ear plugs which say 33db NRR. But then I look at the back and it has a list of frequencies and mean attenuation. None of these are 33db, they are all 38db +. Is the 33db the minimum attenuation or what? If it's minimum 33db, surely going to gigs would be okay using them? They're HEAROS XTREME ones. Say a gig averages 110db - 33db for ear plugs = 77db. I know there's the whole thing about bone conduction, but doesn't the skull provide 40db protection? Thanks!