Voice. Most powerful and natural instrument.

After reading Elizabeth's response I think I'll take the Blue Whale over the current crop of diva's who simply yell as loud as they can. I could only watch two minutes of the Grammys and it was so nauseating to see all of them singing together trying to out diva each other. I was waiting to hear the gong but no one hit it.

I should also clarify that when some can really belt it out that the great ones do it without apparent strain. They don't bend over like they're having a seizure, mouth agape, eyes tightly shut, doing the Joe Cocker thing.
They simply sing way better than the rest of us.