The use of a combination of notes that are fourths apart, known as “stacked fourths” or “quartal voicings,” is a common sound in jazz.
On the guitar, stacked fourths are generally very easy to achieve, as all the pairs of adjacent strings, with the exception of the G and B, are a fourth apart, meaning that if you sound the open low E and A, the open A and D, or open D and G string together, the relationship between the two notes is that of a fourth. The same is true when you sound the B and high E strings. The G and B strings are a major third apart.
This month, I’d like to apply the use of fourths to what is often referred to as “outside” playing. As the term implies, “outside” licks include notes that reside outside the established key and intentionally sound “wrong,” though, to me, they work! In fact, licks like these never sound wrong to me—they sound right by taking you into some other territory, musically speaking, that the listener is not expecting.
A song that represents one of my first exposures to “outside” sounds is a song called “Freedom Jazz Dance,” written by Eddie Harris and famously recorded by Miles Davis, among other jazz artists. The majority of the melody is based on stacked fourths, but here I would like to focus on the very last part of it, as it starts in key but then drifts in and out momentarily, creating a compelling feeling of tension and release.
FIGURE 1 illustrates a two-bar vamp based on Bb7#9, and in FIGURE 2 I approximate the type