So What
So What, recorded by Miles Davis on his Kind of Blue album, marked a beginning of modal jazz. So What is a 32-bar AABA composition using two harmonies: D-7 (or D Dorian) and Eb-7 (or Eb Dorian).
So What Backing Track - I recognize the voice counting as coming from the Jamey Aebersold jazz materials. BTW: Jamey Aebersold has great materials and you should explore his web site.