A Brief Summary of Jazz Scale Use - Introduction
There are three dozen or so scales and modes that may be used for improvisation and some music does require quite a variety of chord/scale types. But a large percentage of music involves only major, minor and dominant 7th chords and requires only a handful of scales. This blog will summarize the small amount of scales needed.
A Brief Summary of Jazz Scale Use - Musical Traditions
As jazz musicians we are affected by two traditions of music, the classical tradition and the jazz tradition. Each tradition has “normal” expected sounds based on the key, types of chords and the location of chords in the key. Both traditions have value and should be considered for their impact on our choices as improvisors. From our experience participating in school choir, band and orchestra and church music we are ingrained with elements of the classical tradition. Our involvement with the jazz tradition stems from our use of extended harmonies (chords with 9ths, 11ths and 13ths) and altered harmonies (chords with chord tones that have been raised or lowered).
A Brief Summary of Jazz Scale Use - Major 7th chords
If we are improvising over a major 7th chord that is the tonic chord (I chord), the classical tradition expectation is to hear a major scale which contains only notes found in the key signature. However, in the jazz tradition, if we build an extended major 13th chord, it contains the scale tones 1, 3, 5, 7, 9, #11, 13. So there is a note that is not in the key, the #11 which is the same as a #4 in a major scale. We do not expect to hear the #4 so it creates a surprise but is still acceptable because it is a chord tone!
So the main question to ask yourself is do you want to hear a natural 4 or a #4? The natural 4 results in a normal, expected sound but the #4 creates a surprise or unexpected sound!
A Brief Summary of Jazz Scale Use - Minor 7th chords
The normal sound (classical tradition) for a tonic chord in a minor key is the natural minor or Aeolian mode. It outlines the minor 7th chord and contains only notes found in the key signature. But in the jazz tradition we have a minor 13th chord, the 13th being the same as a raised 6th scale step in Aeolian mode. Raising the 6th scale step results in a Dorian mode. As before, we expect to hear an Aeolian mode which creates the normal sound of the key but the Dorian mode creates a surprise that is okay to our ears because it reflects the jazz tradition.
So the main question to ask yourself is do you want to hear a natural 6 or a #6? The natural 6 results in a normal, expected sound but the #6 creates a surprise or unexpected sound!
A Brief Summary of Jazz Scale Use - Dominant 7th chords
The classical tradition choice for a dominant 7th chord (which is usually a V chord) is the Mixolydian mode. This is the 5th mode of the major scale and only includes notes that are in the key. In the jazz tradition, a dominant chord may include the 9th, #11 and 13. So the #11 (or #4) is a note that isn’t in the key and creates a surprise in the sound!
So the main question to ask yourself is do you want to hear a natural 4 or a #4? The natural 4 results in a normal, expected sound but the #4 creates a surprise or unexpected sound!
A Brief Summary of Jazz Scale Use - Summary
At least 75% of the music we play involves only major, minor or dominant 7th chords without alterations so, rather than three dozen scales, we can get along nicely at first with only 6 scales! Here is the summary of those scales and the questions to ask.
Major 7th chords - Do we want to hear a natural 4th or a raised 4th?
Natural 4th = Major scale #4th = Lydian scale
Minor 7th chords - Do we want to hear a natural 6th or a raised 6th?
Natural 6th = Natural minor scale #6th = Dorian scale
Dominant 7th chords - Do we want to hear a natural 4th or a raised 4th?
Natural 4th = Mixolydian scale #4th = Lydian, b7 scale
If you encounter other chords or alterations, here is a brief summary of those scale choices:
Half-Diminished 7th - Locrian mode (Major a 1/2 step above the root of the chord)
Diminished 7th - Diminished scale (pattern = W 1/2 W 1/2 W 1/2 W 1/2)
Dominant 7th, Altered 5th - Whole Tone scale
Dominant 7th, Altered 9th - Diminished Scale (pattern = 1/2 W 1/2 W 1/2 W 1/2 W)
Dominant 7th, Altered 5th and 9th - Super Locrian (Melodic Minor a 1/2 step above the root of the chord)