Pentatonic Harmony

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. The pentatonic scale is related to the blues scale and the diatonic scale (it is a subset of both), but it contains no semitones. In popular music, the pentatonic scale is typically found in one of two rotations: the major pentatonic and the minor pentatonic scale (Example 1).

Example 1. Pentatonic scales.

Though the two listed above are the most common, you can build five different versions of the pentatonic scale by simply rotating the notes in the scale.

In rock music, a harmonic system based on the pentatonic scale is typically created by using the scale as chord roots of major triads or power chords (chords with a root and fifth but no third). This leads to collections of chords that don’t belong to any mode or scale (Example 2). Note that in both of the collections of chords in the example below, there is a scale degree “conflict.” The first collection includes both te and ti [latex](\downarrow\hat7, \hat7)[/latex]; the second collection includes both le and la [latex](\downarrow\hat6, \hat6)[/latex].

Example 2. Pentatonic harmony derived from two different rotations of the pentatonic scale.

Though many of the chord progressions drawn from the pentatonic chord families listed above could be accounted for by other schemas, it is helpful to relate them back to the pentatonic scale in this way, due to the scale’s inextricable link to the guitar itself, and especially to guitar solos that are performed in combination with these chord progressions.

Example 3 shows an excerpt from “Higher Ground” by Stevie Wonder (1973), in which the pervasive harmonic loop can be understood as derived from the pentatonic scale.

Example 3. Stevie Wonder, “Higher Ground” (1973).

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