VII. Popular Music
Pentatonic Harmony
Mark Gotham and Bryn Hughes
Key Takeaways
- As discussed in the previous chapter:
- Many pop songs use harmonic progressions that imply modes other than major/minor.
- A modal schema may be used without the entire song being strictly within that mode.
- The pentatonic collection is
- a five-note collection
- a subset of the diatonic collection (that’s also explainable in terms of fifths)
- not one of the diantonic modes, because it has fewer notes, but it can be considered alongside them, especially in this context.
- Chord progressions can be understood in terms of the pentatonic based on their bass notes, whether the chords are major, minor or anything else.
- Partly for this reason, it’s common to see the “same” scale degree in more than one form (e.g., mi and me [latex](\hat3, \downarrow\hat3)[/latex])
This book covers modes from many different angles. For more information on modes, check Introduction to Diatonic Modes (general), Chord-Scale Theory (jazz), Diatonic Modes (20th/21st-c.), and Analyzing with Modes, Scales, and Collections (20th-/21st-c.).
Rock music, and popular music more generally, owes a great debt to the blues tradition. One of the most pervasive pitch collections in pop and rock music is the pentatonic collection, a five-note collection also firmly rooted in the blues.
Basic Scale Materials
The pentatonic scale is related to the blues scale and the diatonic scale: it is a subset of both of those collections that is distinctive for containing only 5 pitches and no semitones. As a 5-pitch collection, there are 5 different rotations of the pentatonic collection (just like there are 7 rotations of the diatonic). In this case (unlikely some 5-note collections) all 5 rotations are different from each other.[1] In popular music, the pentatonic scale is typically found in one of two rotations: the “major pentatonic” and the “minor pentatonic” scales. shows these two main rotations (on the top stave) and then all 5 (on the bottom).[2]
“Scale Degree conflict” a.k.a. “Cross Relations”
In rock music, a harmonic system based on the pentatonic scale is typically created by using the scale as chord roots. The chords can be major triads, minor triads, power chords (chords with a root and fifth but no third), or anything else (including sevenths, added notes etc.). Note that this flexibility in terms of the chord “quality” means that the total pitch collection is often not exclusively pentatonic: often, the chord tones combine to make a collection that doesn’t correspond to the pentatonic, or even any of the 7-note modes we’ve encountered so far.
[3] Both staves show major triads built on the notes of the pentatonic scale.
shows how this can be understood in terms of a “conflict” or “cross relation” between scale degrees.- The first collection (upper stave) is built on the pentatonic in “rotation 1” and includes:
- ti and te [latex](\hat7, \downarrow\hat7)[/latex] colored blue);
- The second collection