Boots wax earplugs. The Gentleman Caller snores, and I find they don't cut the noise out completely, but mute it enough that I can ignore it. They were also very useful when stuck in hospital in an open ward. And convention hotels ... in fact, I never travel without them.

And worse, I use them in the open plan office when the noise gets to me.

If I ever lose my hearing, I wonder if I'll actually notice?!