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What is Jazz? - A look at Jazz Harmony
Published September 10th, 2006. © Chris Juergensen/chrisjuergensen.com. All Rights Reserved.

What is Jazz - A new question opens up a whole new can of worms. In this lesson I will have you take a look at Jazz harmony.

 
Q: Since Rock and Pop music is mostly based on the diatonic chord system from the major scale, is Jazz based on chord progressions using the chords of the diatonic harmonic and melodic minor scales?

A: Well no, not really. First off, I remember being in your position years ago and wondering the very same things that you are. You would figure that since most pop and rock are derived from the harmonized major scale that Jazz and fusion must be derived from the Harmonic Minor and/or Melodic Minor scale. It is not really so. First of all, let me describe my way of classifying tonal music harmonically:

1) Diatonic - Based on definite key centers and diatonic harmony: In other words, music that can be analyzed in a specific key or keys. When you look at a chart of one of these songs, you can find a key signature.

2) Chromatic - Based on unrelated chords with emphasis on modal harmony. Not to be confused with atonal or twelve tone music. Chromatic, but still based on tertian harmony just like diatonic music.

Diatonic harmony is basically what you get in most popular music and in a lot of Jazz too, especially early Jazz. It is important to understand because chromatic harmony will get its start here also. Harmony has generally become more and more chromatic over the centuries. Adding the sevenths to triads hundreds of years ago was a step in the direction of chromaticism. Diatonic music is based on the diatonic system, and as you probably know, there are seven diatonic chords from every key. If you write the melody for your song using the diatonic scale, you can harmonize it by using these seven chords derived from the same scale. We call these chords the "I" and "ii" chords and so on:

I - major (maj7)
ii - minor (min7)
iii - minor (min7)
IV - major (maj7)
V - major (7)
vi - minor (min7)
viio - diminished (min7b5)

Even a lot of Jazz is based on this diatonic system although you are most likely to find several pockets of diatonic tonal centers within the song in question, generally ii-V, ii-V-I, ii-V-I-IV progressions and other combinations of various diatonic chords. Sometimes the tonal centers are from keys in close relation to the "home" key and sometimes far apart. Here is a fairly typical Jazz chord progression that you might find. The tonal centers are in close relation to each other:

 
 

If you where to analyze the previous progression while looking at the circle of fifths, you would find that the four keys used: C, F, Eb and G major are all relatively close to each other, practically neighbors. The example is similar in construction to Miles Davis' "Four" recorded in the early 50's.


In this example, the tonal centers are far apart from each other, major 3rds apart to be exact. John Coltrane used similar compositional techniques:
 
 
There are only three keys and only ii-V-I progressions in the previous example. You may be under the false impression that these diatonic songs are easier to play over than the more chromatic ones but you would be wrong. Songs like John Coltrane's "Giant Steps" has been challenging musicians since it was released in 1959.

Minor iio-V chord progressions

Let's take a look at the minor key iio-V-i chord progression. Unlike the major key ii-V, The iio chord is a min7b5 chord while the V chord remains dominant. Unlike the V chord from the major scale, the V chord from the harmonic minor scale when harmonized as a 9th chord, becomes a 7b9 chord (the major scale will only yield an unaltered dominant 9 chord). Here is the iio-V in C minor. One thing to keep in mind is that while the iio-V is taken from the harmonic minor scale, the i chord is usually (although not always) derived from the natural minor scale, meaning it is not the min(maj7) from harmonic minor but a min7:

 
 
The ii-V progressions became somewhat interchangeable meaning that sometimes the minor iio-V would replace the major ii-V that commonly comes before the major I chord:
 
And leading the way to the more "altered" dominant chords, the 7b9 chord by itself would show up in the major ii-V-I. You can find this in various bebop songs such as "Scrapple From the Apple" by Charlie Parker:
 
 
This an example of how this "modal interchange" occasionally shows up in Jazz:
A good example of a song that uses this technique is "I Love You" by Cole Porter.
Let's take a look at what our original chord progression could be turned into if we replace some of the plain old dominant chords with the 7b9 chords and replace some of the major ii-V progressions with their minor counterparts:
Although it is probably okay to analyze the major ii-V-I progressions as one key, it is important to make a mental note that the V chord is now coming from somewhere else and as an improviser you must play a harmonic minor or altered scale over that chord alone. When the 7b9 chord first started showing up, the soloist was probably most likely to play a diminished arpeggio on the third of the chord. For example, an E diminished arpeggio over the C7b9 chord. This is about the only use for the harmonic minor scale. The other diatonic chords from the harmonic minor scale are almost never used for anything else. That is why, although you hear a lot about the harmonic minor scale, compared to the melodic minor scale, regarding Jazz at least, it is not really as important (my opinion, so don't get mad at me if you don't agree).

Most Jazz up to and even now is still based on these tonal diatonic systems but like all music and animals (disregard animals if you are a creationist) evolution has taken place.


On to melodic minor and more chromatic harmony:

After a while, musicians wanted more harmonic choices for their chords and more modal scale choices than the simple major scale and harmonic minor scale could offer so the melodic minor scale started to get attention. Stepping away slowly from pure diatonic music, musicians would start paying more attention to chromatic and modal harmony and tempos would begin to slow down a bit to allow the soloist to express himself in these new tonal waters. While Bebop is mostly based on diatonic harmony, speed is break neck, forcing the soloist to connect the dots to create a picture. He mostly uses arpeggios to outline the changes. Modal music would force the soloist to draw his picture on a big white piece of paper freehand, paying special attention to phrasing and scale choice. One of the most common "modal" chords would be the altered dominant chord derived from the seventh mode of the melodic minor scale, the altered mode.

Q: Is there a typical "altered" chord? Everyone tells me something different, what is the definitive "altered" dominant chord?

A: The word "altered" is derived from the name of the mode in which the chord comes from, the altered mode of the melodic minor scale. A number of altered chords can be constructed from this mode. Theoretically any dominant chord with an altered 5th and/or 9th and without an unaltered 5th or 9th can be considered altered. You should ask yourself; "Could the altered mode be played over this chord?" If the answer is yes, it is safe to assume that it is altered. Something to think about however: a 7b9 chord could also be coming from the harmonic minor scale and a 7(b5,b9) or 7(b5,#9) chord could be originating from the half/whole diminished scale (although not typical diminished family chords, 13b9 would be more likely). Raised and lowered 5ths by themselves, without an altered 9th present could be coming from the whole tone scale as well. It would seem that the combinations that can't be derived from another scale would be a 7(#5,#9) or 7(#5,b9) chord. Regardless, a dominant chord with both an altered 5th and 9th, whether raised or lowered is pretty much "altered" by my book.


The endless possibilities presented by the use of the harmonized altered mode are a big point of interest to musicians and composers. It is safe to assume that the altered dominant chords started replacing the simple unaltered or slightly altered dominant chords such as the 7b9 chords in ii-V-I progressions first:

You have to keep in mind here that "Modal" harmony was also gaining popularity so the I chord, although technically still the I chord would start to get borrowed from the lydian mode, a maj7#11 chord. So a ii-V-I once being in one key, was now coming from three:
  • Dmin7 - Simply the ii chord in C major, and the easiest to understand in this harmonic context.
  • G7(#5,#9) - Although technically the V chord it is now being borrowed from the altered mode (Ab melodic minor scale). As I mentioned, the altered chord could be many different chords, some possibilities: G7(#5,#9), G7(b5,#9), G7(#5,b9), G7(b5,b9), even chords with combinations of both altered intervals could be constructed, chords such as G7(b9,#9). A lot of time the altered chord symbol is simply notated as G7(alt) and left up to the player.
  • Cmaj7#11 - Finally our I chord is now lydian from the G major scale, harmonized to its full extent a Cmaj7#11 chord. A good example of the "Lydian" chord showing up in Jazz is Miles Davis' "Blue in Green" recorded on the ground breaking record, "Kind of Blue" recorded in 1959."

I need to mention that these altered dominant chords although commonly used, the chord symbols were not necessarily written as such. They where more or less used to add color and tension to the V chord and the choice of how to alter it left up to the guy comping. Later on when some forms of Jazz would loose its diatonic tonal centers, these altered dominant chords (and all "modal" chords for that matter) would become important as compositional tools, meaning that the actual melody lines would contain these altered notes and because of that the symbol would need to be written to make sure the guy comping included the extension or at least didn't add in something to clash with it. So to simplify things, regarding more diatonic music, the altered chord symbol is not necessarily written out but with chromatic harmony, the altered symbol more often is.

Eventually some music would start to branch away from diatonic tonal centers such as the music of Wayne Shorter and the like in the 60s. These songs are not written from specific key centers and have no key signatures. The chords are mostly unrelated and more of a chord/scale relationship is the point to writing. This is the kind of harmony that I refer to as chromatic harmony. Special attention is paid to the modal chord, its extensions and voicing. And when analyzing the music you no longer say that; "this is a ii-V in this key and this is a ii-V in that key." But say; "Oh this G7(b9,#9) is from the G altered mode and this Amaj7#5 is from the A lydian augmented mode. Look how the composer used voice leading and melody to tie them together."

Lets take a look at a hypothetical chromatic/modal chord progression. As I mentioned the voicing are what make this type of writing work so I have included them for you. See if you can analyze it, it is difficult. You can pick out a few tonal centers like the B7(#5,#9) - Emin11 is a V-I and the G7(#5,#9) - Cmaj7#11 is a V-I but other than that, half the chords are unexplainable. The only way you could really analyze it would be to write the modal names underneath each chord: C lydian - B altered - E dorian - C lydian - G lydian augmented - G lydian - C# dorian - G altered. Play it as a ballad and you will see that although mostly unrelated, each chord leads nicely to the next:

 

Q: What are the definitive modal chords, I mean if I had to play the "lydian chord" or "dorian chord" what should I play.

A: Although not always necessary to play the modal chord harmonized to its full extent, it is important to know what they are. Here is what I would consider the definitive modal chords starting from the modes of the major scale:

Dorian - min13 or min6
Phrygian - sus(b9)
Lydian - maj7#11
Mixolydian - 9sus
Aolian - min7(b6)

Now from the melodic minor scale:

Melodic minor - min13(maj7) or min6(maj7)
Dorian b2 - 13sus(b9)
Lydian augmented - maj7#5(#11)
Lydian dominant - 7#11
Locrian #2 - min9(b5)
Altered - 7(#5,#9)

I've left out both the locrian mode from the major scale and the mixolydian b6 mode from the melodic minor scale because they are not of very much use.

So to answer the original question; "Is Jazz based on chord progressions using the chords of the diatonic harmonic and melodic minor scales?

A: Chord progressions are generally not created from the harmonic or melodic minor modes but specific chords are borrowed from these harmonized scales to add color in tonal music. These chords can also and often are used to create modal music in which they generally show up not in diatonic chord progressions but as completely unrelated entities.

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