Jazz accompaniment: comping and rootless voicings

Jazz pianists spend more time accompanying than soloing. Comping (from "accompanying" and "complementing") means laying down light, rhythmic chords that support and push the soloist. Two tools are essential: shell voicings (left hand alone) and rootless voicings (when a bass player is with you).

1. Shell voicings

Two notes in the left hand: the root plus either the third or the seventh. You choose so that the hand moves as little as possible: on a ii–V–I, alternate 1-7, 1-3, 1-7.

M:4/4
L:1/8
Q:1/4=100
K:C
%%staves {RH LH}
V:RH clef=treble
V:LH clef=bass
[V:RH] "Dm7" A2 c2 z c d c | "G7" B4 z2 A F | "Cmaj7" E8 |]
[V:LH] [D,C]8 | [G,,B,,]8 | [C,B,]8 |]

The right hand is free for the melody or improvisation. This is the foundation of every solo jazz pianist.

2. Rootless voicings (A form and B form)

With a bass player, there is no need to play the root: you replace it with extensions (9th, 13th) that enrich the colour. Each chord has two four-note layouts, the A form (third at the bottom) and the B form (seventh at the bottom):

On a ii–V–I, alternate the forms: A – B – A (F A C E → F A B E → E G B D) or B – A – B (C E F A → B E F A → B D E G). One or two notes move each time, by a half or whole step: remarkably smooth.

Above: Dm7 A form (F A C E). No D, and yet you clearly hear a rich minor chord.

3. Comping rhythms

Don't pound all four beats. Comping is a conversation: a few well-placed interjections, often off the beat. The basic rhythm is the "Charleston": one chord on 1, another on the "and" of 2.

M:4/4
L:1/8
Q:1/4=120
K:C
%%staves {RH LH}
V:RH clef=treble
V:LH clef=bass
[V:RH] "Dm7" [FAce]3 [FAce] z4 | "G7" [FABe]3 [FABe] z4 | "Cmaj7" [EGBd]3 [EGBd] z4 | z3 [EGBd] z4 |]
[V:LH] D,8 | G,,8 | C,8 | C,8 |]

Here the left hand plays the bass for reference; with a bass player, the left hand takes the voicings and the right hand stays free or doubles them.

Exercise: three ways to accompany

Start the jazz track in C.

1. Shells. Left hand alone: 1-7, 1-3, 1-7 on each ii–V–I, as whole notes. Then as quarter notes on beats 1 and 3.
2. A/B forms. Left hand: rootless voicings A – B – A, as whole notes. Then start again with B – A – B. Keep the voicings around middle C (roughly between the low D and the high G), otherwise they get muddy or shrill.
3. Charleston. Same voicings in the Charleston rhythm. Then vary: an anticipation on the "and" of 4, a lone chord on 2, a bar of silence…
4. Comping + solo. Left hand: voicings in a free, sparse rhythm. Right hand: a guide-tone line (lesson ii–V–I). Listen for whether the two hands step on each other's toes.
5. Transpose to F with the jazz track in F: Gm7 A = B♭ D F A; C7 B = B♭ D E A; Fmaj7 A = A C E G.