Make loud parts of a clip the same volume as the quiet parts and vice/versa

All my years of working with audio and I've never found a way to do this, though I'm sure there must be.

I'm working with a clip of three people talking. Person number three is considerably louder than persons one and two. How do I make them all the same volume as each other without going into Audition and altering the volume of each section by hand?