What they are
Continuing to stack thirds above the seventh gives the ninth, the eleventh and the thirteenth. On C: C E G B D F A. Tensions color the chord without changing its function.
Available tensions (Berklee chord scale theory)
- Cmaj7: 9 (D), #11 (F#), 13 (A). The natural 11 (F) is an avoid note because it lies a semitone above the third (E).
- Dm7: 9 (E), 11 (G); the 13 (B) is possible in a Dorian context.
- G7: natural 9, 13; altered b9 (Ab), #9 (A#), #11 (C#), b13 (Eb). The natural 11 (C) is to be avoided if the third is present; it is the note of the sus4.
- Am7: 9 (B), 11 (D).
- Bm7b5: 11 (E), b13 (G); the b9 (C) is usually avoided.
- E7 in A minor: typically b9 (F) and b13 (C), from the harmonic minor.
Voicings with tensions
- Remove the fifth first, then the root (the bass plays it).
- Keep the third and seventh: they define the quality.
- Example Cmaj9 in four voices: E G B D. Dm9: F A C E. G13: F B E (with A as the 9).
In stylistic context
- Neo-soul and R&B: m9, maj9, 13 everywhere (Dm9 – G13 – Cmaj9).
- K-pop ballads and city pop: maj7 and 9 on the tonics, 7sus4 on the dominants.
- Melodic trap: m9 and add9 in the pads, tensions left hanging.
Real example
Bill Evans's rootless voicings in “Waltz for Debby” (1961) show how thirds, sevenths and ninths are enough to give the harmony an immediately modern color; the same vocabulary passed into the neo-soul of D'Angelo and Erykah Badu.