Here is a great article about a person with lifelong hearing loss.  Through his life he has repeatedly purchased and used hearing aids and been uniformly dissapointed.  Each one has been little more than an amplifier of sound, which doesn't really solve the problem.

Recently he got a modern cutting edge model.

And then humming.

And I asked, what’s that?

I turned to the audiologist who said, the humming is the light fixtures overhead. I looked up and it occurred to me that the world was opening up in waves around me within this tiny office. I could hear the secretary a room away on the phone and the printer printing and a phone ringing behind me, and I knew right were it was.

Wow! Right now I hear the refigerator running on the other side of the office. And I can make out the highway sounds in the background...just. This guy has NEVER heard the background sounds of life. Until now.

Go read the whole thing.