I had custom-made earplugs when I was regularly performing, and yes, for a musician, they're totally worth it.

Unlike foam or wax earplugs that you stuff in your ear, the custom dealies cut down the decible level evenly across the board, so you don't lose the high end.

But if you're just working in a loud enviroment, there's no justification for spending the money.

We are required to use ear-plugs at certain sites for my job, so our company provides cheap disposable ear plugs. I have no problem hearing and distinguishing voices from different people, although I have not tried them around children.

I have never used custom made earplugs, but I have been using foam earplugs for years as I am a very light sleeper. I also use them when I am studying. I think you can get foam ones with a noise reduction rating of up to 34 or something. As I use mine every night I have to replace them every week or so but I love foam earplugs, they make all noise into a dull and distant sound and they're comfortable.

Here are the official licensed earplugs of NASCAR! (With a "Safety Laws" page)