Why Major Modes? - Introduction
The seven modes of the major scale are extremely useful and are all that is needed to play many tunes written in a major key. Because of this, they should be the first priority for a student of jazz improvisation to learn! Of the seven modes, there are two choices for a major 7th chord, three choices for a minor 7th chord, one choice for a dominant 7th chord and one choice for a half-diminished chord. Since many tunes include only major 7th, minor 7th and dominant 7th chords, a lot of music can be played using only these modes!
Another feature of the major modes is that they line up logically with chord functions in a major key! This results in a strong sound of the key. Following is a summary of those functions:
I ma7 - 1st mode, Ionian (major scale)
II mi7 - 2nd mode, Dorian
III mi7 - 3rd mode, Phrygian
IV ma7 - 4th mode, Lydian
V 7 - 5th mode, Mixolydian
VI mi7 - 6th mode, Aeolian (natural minor)
VII Ø7 - 7th mode, Locrian (Ø7 means the same thing as mi7b5)
The 1st, 3rd, 5th and 7th notes of any mode spell its related 7th chord as can be seen above. Here is a good exercise:
1. Play a major scale and then play the 1st, 3rd, 5th and 7th notes to reveal the related major 7th chord.
2. Play the major scale again starting on the 2nd note and play the 4 tones of the minor 7th chord that is found within that mode.
3. Repeat this process on each note of the major scale always playing the 7th chord inside the mode.
4. As you play all the modes of the scale and their related 7th chords think about their location in the major scale of the key and related type of chord. Example - the 2nd mode is dorian and the chord is a minor 7th.
Once you know the order of the modes, it is convenient to think of the key signature of the major scale from which the mode came. For example, Dorian is the 2nd mode - it’s like starting on the 2nd note of a major scale so it has the same key signature as the major scale a whole step below. Lydian is the 4th mode - it’s like starting on the 4th note of a major scale so it has the same key signature as the major scale a perfect 4th below.
Why Major Modes? - 1. The Ionian mode
The Ionian mode or major scale is important for reinforcing the sound of the key when improvising over a I ma7 because it includes only tones that are in the key signature. We are conditioned by the classical music tradition to expect that sound in relation to the tonic or I chord of a key! Be sure to emphasize the 3rd and 7th notes of the scale which are the 3rd and 7th of the related I ma7 chord. The 1st note of the scale (the root of the I ma7) should normally resolve to the 7th because it is a characteristic tone in the I ma7 chord that would normally be included in a typical voicing of the chord by a pianist or guitarist. The 4th scale tone is very dissonant against the 3rd of the chord and should resolve to the 3rd (the Amen of jazz!). Any other tone of the scale may be emphasized without a problem!
Why Major Modes? - 2. The Dorian mode
The 2nd mode (Dorian) is used with a II mi7 in a major key. This is important to ensure that the chord will sound like it is in the right key! For example, if you have a II mi7 (D mi7) in the key of C Major and you play a D natural minor scale with Bb, it will sound as though you have changed key because there is no Bb in the key of C major! So it is useful to remember that a II mi7 in a major key will always require the use of a Dorian mode. The Dorian mode actually includes all the chord tones of a minor 13th chord - 1, 3, 5, 7, 9, 11, and 13. Therefore any scale tone may be emphasized in relation to the II mi7 chord. The 2nd and 6th notes of the scale are slightly more dissonant but may be emphasized because the are chord tones of the minor 13th chord.
Why Major Modes? - 3. The Phrygian mode
The Phrygian mode is not used as often as Dorian or Aeolian because it has a b9 which is not a normal alteration in a minor chord. If the composition is written in Phrygian mode, then the mode can be used because it is a part of the sound of the piece. The characteristic note is the 2nd scale step which is dissonant against the root! Since the Phrygian mode is the 3rd mode of the major scale, it can be used with a III mi7 to be consistent with the sound of the key. A III mi7 is a substitute for the I ma7 in a major key and since Phrygian is the 3rd mode of the major scale, it is the same sound as playing the major scale of the key on the I ma7!
Why Major Modes? - 4. The Lydian mode
The 4th mode (Lydian) is used with a IV ma7 in a major key. This is important to ensure that the chord will sound like it is in the right key! For example, if you have a IV ma7 (F ma7) in the key of C Major and you play an F major scale with Bb, it will sound as though you have changed key because there is no Bb in the key of C major! So it is useful to remember that a IV ma7 in a major key will always require the use of a Lydian mode. The Lydian mode actually includes all the chord tones of a Major 13th chord - 1, 3, 5, 7, 9, #11, and 13. Therefore any scale tone may be emphasized in relation to the IV ma7 chord. The 1st note should resolve to the 7th as in the case of the Major scale.
Why Major Modes? - 5. The Mixolydian mode
The 5th mode (Mixolydian) is used with the dominant 7th V chord of a major key. If the chord doesn’t contain any alterations, then Mixolydian will outline the V7 chord and reinforce the sound of the key. In a Mixolydian scale, the 4th scale tone is very dissonant against the 3rd of the related dominant 7th chord and should resolve to the 3rd (the Amen of jazz!). Any other tone of the scale may be emphasized without a problem!
Why Major Modes? - 6. The Aeolian mode
If a VI mi7 is to sound like it’s in the right key, an Aeolian mode should be used. That scale is consistent with the major key signature of the I ma7 chord (C major = A Aeolian). The 6th scale step is dissonant in relation to the 5th of the VI mi7 and should resolve to the 5th. Any other note in the scale may be emphasized.
Why Major Modes? - 7. The Locrian mode
The Locrian mode is used with a half-diminished (minor 7b5) chord which does not commonly occur in a major key. However, in a minor key, the II chord is a half-diminished chord and occurs frequently as part of the II-V-I chord progression.
Why Major Modes? - 8. Some optional choices
As indicated before, the Ionian mode (major scale) is the normal choice for a I ma7 in a major key. However, the Lydian mode includes the all the chord tones of a major 7th chord and could be used with a I ma7. This would create a surprise effect since the scale includes a raised 4th scale step that is not in the key. For example, a C Lydian scale would have an F# because it is the 4th mode of a G major scale. If it is used with a C ma7 I chord, the F# is not expected!
The aeolian mode is normally used with a VI mi7 but a Dorian scale could be used. Again, it would introduce a surprise because the raised 6th tone in the Dorian scale is not in the key! For example, if you use an A Dorian scale with an A mi7 VI chord in C major, it introduces an F# which is not in the key.
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