Pitch axis theory

For inversion about a central pitch of a melody, see Inversion (music)#Pitch axis.

The Pitch axis theory is a musical technique used in constructing chord progressions. The tonic is used as the bass note, and melodic scales are chosen according to the chords that lie beneath them. Pitch axis theory was introduced to guitarist Joe Satriani by his high school music teacher Bill Wescott .

The pitch axis is the pitch common and most important to, the tonic of the initial key, all chords in a chord progression

Concept

The seven modern modes are all connected to each other by diatonic shifts; that is, C Ionian (C-D-E-F-G-A-B-C) is also D Dorian (D-E-F-G-A-B-C-D), E Phrygian (E-F-G-A-B-C-D-E) and so on, until you return to the original C Ionian Mode. Therefore, each of the seven modes of any of the twelve major keys is also a mode for another six of the modes in that particular key.

Pitch axis theory suggests that for each mode, there is a chord that accompanies it. When that chord occurs, the corresponding mode should be used for the melody or for soloing.

The more common modes, along with their chords:

Mode	Chord(s)
Ionian mode	Maj6, Maj7
Dorian mode	Min6, Min7
Phrygian mode	Min7, Min7b9
Phrygian Dominant mode	7, 7b9
Lydian mode	Maj7, Maj7#11
Mixolydian mode	Dom7, Dom9, Dom11
Aeolian mode	Min7, Min9, Min11
Locrian mode	Min7b5, Min7b5b9

This is the first part of pitch axis theory. The second step is implementing these modes as chords built on a common root. This is best shown with an example.

Examples

For example:

         lydian
       ABC♯D♯EF♯G♯
           | 
           |
aeolian -- A -- locrian
ABCDEFG    |   AB♭CDE♭FG
           |
       mixolydian
        ABC♯DEF♯G

Thus the non-diatonic chord progression constructed from chords diatonic to each mode:

| A5#11  | A7sus4     | Fmaj7/A | A7sus4     |
|A-lydian|A-mixolydian|A-aeolian|A-mixolydian|

"Satch Boogie"

"Satch Boogie" bridge progression  Play .

"No better demonstration of the Pitch Axis device exists than the famous tap-on bridge of 'Satch Boogie'", originally played only on the fifth-string.

Example 1: Joe Satriani - Not of This Earth

The chords from Joe Satriani's "Not of This Earth"  Play .

This song is fully based on the pitch axis of E.^{[citation needed]} The chords E major 13, E minor 7 sharp 5, E major 13, and E 7 suspended 4 imply a transition between E Lydian, E Aeolian, E Lydian, and E Mixolydian. This pattern continues throughout the song, keeping a strong feel of tonality while changing through the modes in a rather disorienting way.

The chord E minor 7 sharp 5 is not a perfect match for E Aeolian. When spelling out the mode to use over this chord, instead of thinking of the chord as E minor 7 sharp 5 (E-F#-G-A-B#-C-D-E), think of it as E minor 7 add 6 (E-F#-G-A-B-C-D-E). Otherwise, the E diminished scale might be a good choice (E-F#-G-A-A#-C-C#-D#-E)

It is also important to note than in conventional music theory, there is no such thing as an E minor 7 sharp 5 chord. This chord (spelled E, G, C and D) is really a first inversion C major chord with an added 9th (the D), which could also be thought of as a C major chord with an E in the bass, or C/E. From here you could choose to use either a C Ionian or Lydian scale, which would correspond to an E Phrygian or E Aeolian respectively. Whilst this might seem to be making the chord more complicated, it also helps to explain the relative lack of tension and 'major' sound of the chord.

Example 2: Dream Theater - Lie

The chord progression from "Lie" by Dream Theater.

The break in Dream Theater's "Lie" is built on Pitch Axis Theory.^{[citation needed]} The bassist plays B while the guitarist and keyboardist imply the chords in the progression: B minor, B minor 7, C# dominant 7, and E minor.

The scales used for each of these four chords are B Aeolian(natural minor), B Dorian, C# Mixolydian, and E Aeolian, respectively. However, as these are all diatonic modes, they can all be thought of as being based on the root of B. If the scales are shifted to start on B, then the progression appears as B Aeolian, B Dorian, B Lydian, and B Phrygian.

Artists who use pitch axis theory

These artists use pitch axis theory and shifting modes in their music.

• Joe Satriani
• Dream Theater
• Steve Vai
• Marty Friedman
• Guthrie Govan
• Planet X
• Yngwie Malmsteen
• Greg Howe

Related music theories

• Modal jazz
• George Russell's Lydian Chromatic Concept of Tonal Organization (1953)
• Polymodal chromaticism