Tensions

If you’ve ever read a chord chart, you’ve likely encountered symbols like this: Cmaj7#11, G7b9, or Dm7b9. Depending where you were at on your journey toward harmonic brilliance, you either knew to play a Lydian sound over the Cmaj7#11 chord, an altered dominant scale over the G7b9, and a Phrygian tonality on the Dm7b9 or you simply ignored the 11s, 9s, and 13s and stuck to outlining the root triad or seventh chord. While the latter approach is perfectly acceptable, it excludes the colorful tones that help make music interesting. These “extensions” or “tensions” are notes beyond the basic 1, 3, 5, and 7 formula of chord construction, and understanding them is a crucial step in any player’s musical development.

A chord gets its primary sound from the root, 3rd, 5th, and 7th, although the 5th isn’t quite as important as the other three chord tones. Changing any one of these chord tones while leaving the others the same alters the chord’s harmonic function. Tensions don’t affect chords harmonic function but do add color and texture and can improve voice leading between chords. The numbers 9, 11, and 13 simply represent the 2nd, 4th, and 6th of a chord but an octave up. Ex. 1 shows a C major scale in two octaves. Note that I’ve numbered each note, but that I didn’t start at 1 again when I hit the first octave. As you can see, the D, F, and A are numbered 9, 11, and 13 in the second octave. We use these numbers when referring to tensions because tensions are often played in a range above the chord tones, mostly because a large bunch of notes clustered in single-octave register sounds harsh. If you’re ever confused about what note a tension number refers to, just subtract seven.

When speaking of tensions, you’ll often hear terms like “available tensions” and “avoid notes.” While music is infinitely filled with breakable rules, in most circumstances, there’s a system for deriving which tensions will work on a particular chord. To start off, the simplest way to pick diatonic tensions for a given chord is to stack diatonic triads starting at the 7. The bottom staff of Ex. 2 shows all the diatonic 7 chords starting from the I chord (I’m using C major in this case, but these rules apply to all major keys). The top staff shows the diatonic tensions for each chord, their intervals from the root, and the quality of the triad they produce. The first bar of Ex. 2 shows a Cmaj7 chord in the bottom staff and the notes D, F, and A in the top staff. D is the 9 of Cmaj7, F is the 11, and A is the 13, and together they are a Dm triad. The rest of the bars of Ex. 2 show the available tensions for the other diatonic chords in a major key. I suggest memorizing the “tension triad” for each diatonic chord in major harmony. For example, the tensions for Cmaj7, or any I chord, could also be described as a minor triad a whole-step up from the root. Similarly the tensions for the IV chord, in this case Fmaj7, make up a major triad one whole-step above the root.

A Note to Avoid
Using the system in Ex. 2, we see that the Cmaj7 chord contains a note, F, which actually sounds ugly against the chord (if you have a piano, try playing a Cmaj7 with an F on top. Yuck.) This ugliness is why the 11 is considered an “avoid” note. While its playable as a passing tone over a major chord, emphasizing the natural 11 sounds clash-y with the 3rd of the major chord. While half-step distances between a chord tone and a tension are common, clashing with the all-important 3rd is a bit too much for our ears to handle. Because of this, the 11 is often raised a half-step over major chords, creating a #11 and making for a prettier sound. This is one of several examples of a tension’s sound dictating a departure from the diatonically available notes. We’ll explore some more examples in an upcoming column.

There’s much more to cover with tensions. Perhaps most important, tensions help clue an improviser into an appropriate scale for a given chord. For example, an Am7b13 chord suggests an Aeolian scale—a minor scale with a b6 (b13). But with an Am13, the composer is clearly suggesting a Dorian sound, a minor scale with a natural 6 (13). Tensions start getting really crazy over dominant chords, as these already tense chords love to be decked out with as much tension as can be piled on. For now, try arpeggiating diatonic major chords beyond the 7th. Ex. 3 demonstrates the first three arpeggios in the key of C; you’ll have to figure out the rest on your own. Regarding naming, the tension number that follows the chord symbol usually implies that chord tones and tensions beneath it are also available, so a 13 chord generally includes the 9 and 11, which are natural unless otherwise specified. Also, if you have access to a piano, experiment with playing the chord tones in your left hand and the tensions in your right. You’ll immediately hear their beautiful benefits.


Thank you to Jonathan Herrera