Surefire makes good comfortable reusable earplugs that aren't too visible (if you buys the transparent ones). They're not as effective as foam earplugs, but often that 10-12dB is good enough! Some models have holes you can plug/unplug to increase or decrease the amount of sound blocked.

They're often promoted for firearms use. However I don't own a gun and I enjoy mine for loud clubs and the like.