Earplugs attenuate, they don't blank the way say stereo earpieces do.
My hearing is damaged (both loss and tinnitus) from guitar amps and I would recommend musicians earplugs which allow all frequencies but lowered rather than the basic foam plug things.
This sort of thing helps me keep what I have left
ps Some makes have a long protrusion, you want the short ones for in a helmet
http://www.ebay.co.uk/itm/PROGUARD-L...item232e043e8f