Usually when playing along with jazz standards we check out the changes before we start, the changes define the song.

I was wondering if it is possible to not have a predetermined set of changes before the song starts, but to be able to improvise them as you are playing.

Related questions, with answers:

  • 2
    I've been there and done it. It takes both players to listen well, and be able to move together. Sadly, no recordings, but it can, and does happen, and it's magic when it does. No need to even have a key in mind, it's uncanny, but wonderful when it happens. Not very often though...
    – Tim
    Mar 6, 2021 at 20:27
  • Phish improvises lots of music and changes, but you don’t have to agree ahead of time to take turns. You just have to know each other and listen carefully. Hand signals and/or signal riffs don’t hurt either. Mar 6, 2021 at 21:31
  • I'm voting to reopen as this now asks about a very specific technique in jazz. It most often occurs in two contexts: when the soloist "plays outside" the chord changes, and the rest of the band follows. Some great examples of where to hear that are in the classic Coltrane quartet, in the Joshua Redman quartet from the 90s (check out Brad Mehldau's solos and listen for how bassist Christian McBride follows Brad away from the chord changes).
    – jdjazz
    Mar 14, 2021 at 21:11
  • 2
    Right, @jdjazz isn't the concept of free jazz based on improvising every aspect of music? Mar 14, 2021 at 21:22
  • 1
    Free jazz crossed my mind too. I didn't include it because I think it's more accurate to say that free jazz doesn't have defined chords. When playing free jazz, I think the goal usually isn't to improvise agreed-upon chords that the entire band plays together at the same time. The structure of everyone playing the same set of chords isn't usually there. That's different from playing outside the changes, which tends to follow a more predictable pattern (e.g., a half-step up, etc.) and often involves staying on a single "new" chord for a longer period of time (allowing the band to catch up).
    – jdjazz
    Mar 14, 2021 at 21:32

1 Answer 1


First of all the changes do not define the song. Any tune from the Real Book, or other sources, can be harmonized by several different sets of chords, you have many options for this. The Head defines the tune. If you look at a few dozen tunes from the Real Book at random you will likely find a few common sets of changes. If all anyone did was follow the changes then every tune would sound the same and solos would be boring. Improvisation is variation on a theme. The Head is the theme and that is where you get the most bang for the buck.

That all being said, in western music changes naturally arise from the melody and application of a few simple rules. If you really understand the rules of harmony theory you can harmonize as you go. Piano players and guitarists do this all the time. With the melody in front of you you definitely can "improvise" changes. Given some knowledge of the circle progression, cycle extensions, and substitutions you could get some pretty intricate harmonization of even a simple melody. Being able to do this takes a lot of practice in my experience but it is possible.

If this is not what you were asking about, please comment and I'll edit the answer.

  • At the time of the post, I didn't quite understand that the changes didn't define the song, I get that we can harmonize a melody with different sets of chords now. What I wonder now is if we have a guitar player and a piano player how can they both improvise the harmony together without clashing? With respect to my original question, what I was trying to ask is if it's possible for a melody to be improvised and simultaneously have someone harmonize it (improvising chords for it). Jan 4, 2022 at 2:18
  • That would likely lead to a mess. One person has to lead and the others follow. With NO idea to start with cohesion is not likely or easy. At the very least you could pick a key and see what happens but even then you would likely run into situations where the two player move in directions that "clash". You cannot predict what you haven't heard, or seen. One possibility is voice leading. If both players are equally well developed and one moves the other can kind of predict what the next move is likely to be. There has to be some template, 16 bars, 12 bars, where should the resolution go.
    – user84734
    Jan 4, 2022 at 2:30
  • etc. (I ran out of characters).
    – user84734
    Jan 4, 2022 at 2:31
  • Let's say you have a drummer, saxophone, guitar and piano. In this situation if everyone knows the standard they're going to play and the guitarist and pianist just play the stock chords, everything will go smoothly and sound predictable, if we just give them the melody and let them harmonize it might work out, if we don't give them any lead sheet at all and say "play" then it's a train wreck. How do we strike the perfect balance ? Jan 4, 2022 at 3:35
  • 1. They will not play stock chords. Why would they. If they know the standard they have many compatible options. Substitutions usually work well together.
    – user84734
    Jan 4, 2022 at 11:12

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