Hearos are about $5, re-usable and offer a 30db model. That's about the maximum you can go before you're contending with the vibrations affecting your skull aff

Hearos are about $5, re-usable and offer a 30db model. That's about the maximum you can go before you're contending with the vibrations affecting your skull affecting your inner ear being louder than what's coming through the ear canal.