In our previous lessons on chord progressions, we discussed the diatonic chords in both major and minor keys (triads and seventh chords). The slides for that portion of the lesson are included below. An examination these slides reveals that the most common chords in music are the major seventh (or major triad), minor seventh (or minor triad), dominant seventh and the minor seven flat five (also known as half diminished). These are also the chords that are used in music's most common chord progression, the 2-5-1 chord progression. I mention both triads and seventh chords here, but seventh chords are usually more common in jazz music. Although fully diminished seventh chords (and diminished triads) do exist in music, they are used less often. For the purpose of this lesson, we will examine the most common chords listed above, and the modal scales that they relate to best.
In the same way, the pitches of minor triads and seventh chords most closely resemble the pitches of the Dorian scale. The pitches of dominant seventh chord most closely resemble the pitches of the Mixolydian scale. Finally, the pitches of minor seven flat five chords most closely resemble the pitches of the Locrian scale. This means that a musician can use these scales as a pool of acceptable pitches when creating jazz improvisation over these chords. In addition, the Lydian scale can be used when improvising over an major seventh chord with a raised 11. The sharp 4 of the Lydian scale helps to accentuate the raised 11 of this chord.
In modal improvisation, another tasteful practice is to accentuate the differences in pitch between adjacent modal scales. Some chord progressions (like 2-5-1) will share the same pool of pitches (Dorian - Mixolydian - and Ionian that are all from the same key center). However, when the music moves to a chord who's scale is based in a different key center, accentuating the new pitch (or pitches) helps to embed the sound of the chord changes within the improvisation. A teacher once told me that he should be able to hear the chord changes in my improvisation even when there is no accompaniment present.
Jazz improvisation is a beautiful form of musical expression. I think of it as instant melodic composition guided by a framework of predetermined chords. Although there are many methods a musician can employ when improvising, the use of modal scales (as discussed in this lesson) can be a great starting point.
In this Learning Music With Ray video I discuss the use of modal scales in jazz improvisation. I list the most common chords used in jazz and the modal scales that best outline the notes of each chord. Finally, I demonstrate a modal improvisation over the chord changes of one of my original songs, and explain the improvisational choices I made.