Yea, don't bother with the ear plugs :roll: That's just covering up the problem, not fixing it. Actually, they don't work at all.
Do you have access to a round pen? If so, here is what I would do. Stand in the center of the pen while mounted on your horse. Have someone else on the OUTSIDE of the pen on a nice, quiet, easy going horse. They walk around the outside of the pen right next to the fence while you pivot your horse around facing them. Slowly work your way so that your horse then goes in a small circle, going with the other horse. Slowly make your way out so that eventually your horse walks next to the other horse (still on the outside of the pen). Then have them pass you. If your horse gets nervous and impulsive, bend him to a stop using one rein. Have the other person inch out ahead slowly, a little bit at a time. Then you can graduate into an arena.
If at any time your horse gets impulsive or nervous in the beginning of what I described, back off from that threshold and go back to a smaller circle. This will build his confidence.