What sort of earplugs are you using? I actually had the opposite problem. I was using normal wax earplugs and I basically couldn't hear a thing with them in. Ended up getting a custom set of earplugs from this company: http://www.earplugstore.com/...olded-ear-plugs.html
They make a version with a hollow cavity that makes it possible to hear someone (like a coach) on a pool deck.