Hi there
I was using hearing protectors! They are yellow in color, and come 4 to a package. I got those at Home Depot too! I cannot for the life of me remember what I paid for them, however if your husband, son, daughter or friend works for a place that makes loud noises, these ear protectors are generally available to them. I'm not suggesting that you ask them to steal for you, however if a few fall your way every now and again, keep them!
However your idea looks simple enough and looks like a great idea!
TreeFrog