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Blues-based schemas, or “flat-side” schemas, are those that mostly employ harmonies found on the “flat side” of the circle of fifths. We draw the connection to the blues here because of its propensity for using the IV chord (the first chord found in the flat-wise direction on the circle of fifths), and for the general ubiquity of the flattened seventh scale degree in blues music.

Plagal Motion

The IV chord, while certainly an extremely frequent predominant/subdominant chord in common-practice repertoire, has an even more prominent place in pop/rock music. Perhaps borne out of the 5–6 neighboring motion found in shuffle-blues guitar accompaniment patterns (Example 1), an alternation between I and IV is a common occurrence in numerous genres (Example 2).

https://musescore.com/user/32728834/scores/5804531/embed

Example 1. The 5–6 shuffle pattern.

https://musescore.com/user/32728834/scores/5804559/embedExample 2. The plagal IV–I pattern.

In “Soul Man” by Sam and Dave, the chord progression used in the verse (Example 3) consists of an alternation of I and IV—listen carefully to the bass.

https://musescore.com/user/32728834/scores/5804585/embedExample 3. Sam and Dave, “Soul Man” (1967).

A similar oscillation between I and IV can be found in the verse to “In the Midnight Hour” by Wilson Pickett (Example 4). Perhaps unsurprisingly, this track features the same guitarist and bassist as “Soul Man” (Steve Cropper and Donald “Duck” Dunn, respectively).

https://musescore.com/user/32728834/scores/5804779/embed

Example 4. Wilson Pickett, “In the Midnight Hour” (1965). 

This kind of chord progression isn’t limited to soul and R&B, of course. The beginning of “After the Gold Rush” by Neil Young (Example 5) features a similar progression (it deviates after the the words “…drummers drummin’…”; also, note the discrepancy between the melody notes and the chords throughout).

https://musescore.com/user/32728834/scores/5804789/embed

Example 5. Neil Young, “After the Gold Rush” (1970).

Minor iv

A very common plagal schema in rock and popular music is the use of the minor iv chord as a kind of cadential gesture. It is most commonly found as part of the three-chord schema IV–iv–I. The schema is typically accompanied by the descending melody la–le–sol [latex](\hat{6}-\downarrow\hat{6}-\hat{5})[/latex], which is found in the guitar part in Example 6. The semitone descent creates an especially strong pull to the tonic.

This descent has been referred to  by J. Kent Williams and Frank Lehman as a “plagal sigh” in Golden Era American popular song and Classic Hollywood film scores, respectively.^[1] Both authors consider this gesture to invoke a sense of nostalgia and sentimentality. Indeed, even in pop music, musicians typically use this progression in conjunction with lyrics that suggest sentimentality.

“Wake Me Up When September Ends” by Green Day (Example 6) exhibits both of the tendencies discussed above: motion from IV–iv–I and a sense of nostalgia and sentimentality in the lyrics.

https://musescore.com/user/32728834/scores/5810544/embed

Example 6. Green Day, “Wake Me Up When September Ends” (2005). 

Double-Plagal

The “double-plagal” progression (Walter Everett’s term) is an expansion of the plagal progression discussed above to include the IV/IV chord prior to the IV chord.^[2] This is perhaps more simply explained as ♭VII–IV–I. The most famous instance of the double-plagal progression is likely the coda from “Hey Jude” by the Beatles (Example 7).

https://musescore.com/user/32728834/scores/5807341/embedExample 7. The Beatles, “Hey Jude” (1968).

Extended Plagal

The “applied IV” chord can be used in sequence, similar to the descending-fifths progression in common-practice music. In the version of “Hey Joe” by Jimi Hendrix (1966), the verse consists of three iterations of the plagal motion in a descending-fourths pattern, which results in the progression ♭VI–♭III–♭VII–IV–I, in the key of E major.

https://musescore.com/user/32728834/scores/5807378/embedExample 8. Jimi Hendrix, “Hey Joe”  (1966).

Recognizing Blues-Based Schemas

In all of these examples, the sense of forward motion is created by the harmonic motion from IV to I. The other alterations, such as IV/IV (♭VII) or minor iv, are extra embellishments on this essential plagal motion.

• Williams
• Lehman
• Everett

1. Listening for blues-based schemas (.pdf, .docx). Asks students to identify blues-based schemas, their use, and any variations in three pop songs. Worksheet playlist