My girlfriend tries to remember earplugs when she flies. The problem with useable earplugs is that for them to work, they must be in your ear canal, which is not where you want them when experiencing pressure changes.
It may be illegal to drive with earplugs, though I may try it (being in the construction biz, I get earplugs for free) since I'm deaf in one ear and have no directional hearing. If I hear a siren, I have literally no idea where it is or whether it's a potential hazard to me until I see the associated flashing lights. So I may already suffer the worst of the negative effects of using earplugs while driving.
