Voice. Most powerful and natural instrument.

124db is incredible. And what about blue whales?

you tube: "Elmos bedtime lullaby" sung by Denyce Graves

Getting a Blue Whale on stage to sing opera would be a challenge.
See: "Willie the Operatic Whale" (Willie wants to sing at the Met... a old Disney short)
The Dallas Opera is featuring "Moby dick" (Jake Heggie)
Wonder who gets to play the whale?
(Yeah, I can get seriously louder than any of my friends.. and can speak very clearly, very loud. Louder than a person with a bullhorn, and way clearer. Maybe i was an opera star in a past life? Normally i speak pretty softly.)

Tenor Sax or piano.

And in the future life?
What kind of system would one need to reproduce blue whale's singing realistically, I wonder?
Anyway, it appears that everyone more or less agrees with my original statement about human voice.