# AI Wiki - Music - Voice Leading ## Concept Voice leading (also "part writing") is how each individual note in a chord moves to its note in the next chord. Wikipedia frames it as the linear progression of individual melodic lines, and how those separate lines combine into harmonies. Every chord is made of several lines, even on one instrument, and your ear follows those lines whether you think about them or not. Why care? Because the same chord progression can sound clumsy or smooth depending only on which notes you pick. If every chord jumps to a new position, the hand travels a lot and the music sounds like a list of unrelated shapes. If each note moves as little as possible, you play less, you hear more connection between the chords, and the whole thing becomes easier to play. Good voice leading is mostly laziness applied with taste. ## The four basic rules Wikipedia lists the conventions that come out of centuries of common-practice harmony. They boil down to this: 1. **Keep common tones.** If two chords share a note, leave it where it is. Dürrnberger called this the "law of the shortest way." 2. **Move by step.** When a note has to move, prefer the nearest note (a half step or whole step). Avoid leaps, and after a leap, go back the other way. 3. **Use contrary motion.** When there is no common tone, move the other voices in the opposite direction from the bass. If the root goes up, the upper notes go down. 4. **Avoid parallel fifths and octaves** between any two voices (more on that below). Rule 1 and 2 are the practical ones. If you only remember "keep what you can, move the rest by the smallest step", you already voice-lead better than most beginners. ## Example: C to F to G on piano Played all in root position, the hand jumps up and down the keyboard: ```progression I IV V key: C instrument: piano title: C, F, G in root position: the hand jumps ``` Now keep the hand in place. C stays as is. For F, the nearest voicing is the second inversion (C F A): the C is shared and stays, E moves up to F, and G moves up to A. Then for G, the nearest voicing is the first inversion (B D G): C drops to B, F drops to D, A drops to G. ```progression I IV V key: C instrument: piano voice-leading: yes title: Each chord in the inversion nearest the one before ``` Compare the two sets by counting semitones. In the first version every note moves 5 and then 2, so the three notes travel 21 semitones in total. In the second version they travel 3 (0 + 1 + 2) and then 6 (1 + 3 + 2): 9 in total, and the hand never leaves one spot. The right hand barely moves. This is the whole point of [[AI Wiki - Music - Piano Chord Inversions|inversions]]: they let you pick the voicing closest to the previous chord. The bass can then play the real roots (C, F, G) with the left hand, and the right hand glides. ## Contrary motion and the bass When the right hand moves up, a left hand playing the roots can move down (or the other way round). The two outer lines pull in opposite directions, which keeps the harmony clear and avoids the empty feel of everything sliding together. A typical piano move: the left hand plays C, then F, then G (up a fourth, then up a step) while the right hand plays the nearest inversions, which go up, then down. The rules come from Renaissance and Baroque counterpoint; see [[AI Wiki - Music - Classical Music]] for where to study it, and [[AI Wiki - Music - Gospel Music]] for the same smooth motion in passing chords. ## Parallel fifths and octaves Two voices a perfect fifth (or octave) apart that move together to another fifth (or octave) lose their independence: they fuse into one line with a thicker sound. Wikipedia's voice leading page says that to be independent, voices "should avoid parallel fifths and octaves", and the consecutive fifths page says they are avoided "in part because they cause a loss of individuality between parts". Both warn about hidden consecutives, where two voices land on a perfect interval by moving in the same direction. This is a rule from classical counterpoint and chorale writing, where four separate vocal lines should sound like four people. It is really not a universal law: - **Rock and pop ignore it constantly.** [[AI Wiki - Music - Power Chords]] are root plus fifth, slid up and down the neck: parallel fifths all the way. Wikipedia makes the same point: power chords in progression create parallel fifths, and the prohibition does not apply because nobody is trying to write independent voices. - **Doubling a line in octaves** is a standard production trick (bass and guitar, or piano left hand in octaves). - **Parallel triads** (a whole shape slid along the neck or keyboard) are used on purpose in impressionist classical music and in a lot of soul and gospel guitar playing. So treat it as a tool for knowing what you're giving up. If you want four independent voices (a hymn, a string arrangement, a piano piece in a classical style), avoid parallels. If you want power, keep them. ## Guide tones: the 3rds and 7ths In a seventh-chord progression the notes that define each chord are the **3rd** (major or minor quality) and the **7th** (the tension). Jazz players call the 3rd and 7th the **guide tones** (Jazzify defines them as "the 3rd and 7th of each chord"). The root is often covered by the bass and the 5th adds little. Guide tones also move very little from chord to chord. Take the ii-V-I in C: Dm7, G7, Cmaj7. | Chord | 3rd | 7th | |---|---|---| | Dm7 | F | C | | G7 | B | F | | Cmaj7 | E | B | Read each column as a line: - 3rd of ii (F) stays on F as the 7th of V, then drops a half step to E, the 3rd of I. - 7th of ii (C) drops a half step to B, the 3rd of V, then stays on B as the 7th of I. So the two lines are F, F, E and C, B, B: two lines that move only by half step or not at all. Jazzify describes the same pattern: the 7th of each chord falls a half step to the 3rd of the next, and a shared note stays in place. That's the main reason a ii-V-I sounds smooth; see also [[AI Wiki - Music - Seventh Chords]] for how each chord is built. On piano, play the guide tones in the right hand with the root in the left: ```progression ii7 V7 Imaj7 key: C instrument: piano voicing: shell hands: left+right ``` The left hand plays D3, G2, C3. The right hand plays F4-C5, then F4-B4 (F stays, C drops to B), then E4-B4 (F drops to E, B stays). These are the "shell" voicings of [[AI Wiki - Music - Piano Voicings]]: root, 3rd, 7th, and nothing else. You can add the 9th or 13th on top later without changing the guide-tone lines. In a minor key the ii-V-i is iiø7-V7-i7, and one guide tone moves by a whole step. In A minor (Bm7♭5, E7, Am7), with both hands as above: ```progression iiø7 V7 i7 key: A minor instrument: piano voicing: shell hands: left+right ``` The left hand plays B2, E2, A2. The right hand plays D4-A4, then D4-G♯4 (D stays, A drops to G♯), then C4-G4. One line falls by half steps: A (7th of Bm7♭5), G♯ (3rd of E7), G (7th of Am7). The other line holds D (3rd of Bm7♭5, then 7th of E7) and then falls a whole step to C, the minor 3rd of Am7. The G♯ is the raised 7th of A minor: it makes the V a major chord, and it falls back to G because Am7 takes the natural 7th. ## Applied on guitar On guitar, voice leading means keeping the hand in one area and moving only the fingers that have to. Two techniques help: **1. Sharing a string set.** The ii-V-I in G with the roots on the 6th and 5th strings and guide tones above. Am7 (ii), D7 (V), Gmaj7 (I): ```chord columns: 3 --- frets: 5x55xx fingers: 1x23xx title: Am7 shell (A, G, C) --- frets: x5x57x fingers: x1x23x title: D7 shell (D, C, F#) --- frets: 3x44xx fingers: 1x23xx title: Gmaj7 shell (G, F#, B) ``` The 7th of Am7 (G) drops a half step to F# (the 3rd of D7) and F# stays as the 7th of Gmaj7. The 3rd of Am7 (C) stays as the 7th of D7, then drops to B. Same two moving lines as on piano, in a different key. See [[AI Wiki - Music - Guitar Seventh Chord Voicings]] for fuller shapes. **2. Open chords with a common tone.** In open position, a chord change like Am to Am7 to Dm7 or C to Am can keep fingers down. Cmaj7 (x32000), Am7 (x02010), Dm7 (xx0211) and G7 (320001) in C are a good example: look at which fingers can stay put in the I-vi-ii-V turnaround: ```chord columns: 4 --- Cmaj7 x32000 x32000 --- Am7 x02010 x02010 --- Dm7 xx0211 xx0231 --- G7 320001 320001 ``` Going from Cmaj7 (C E G B E) to Am7 (A E G C E), the E on the D string stays under the same finger, and G and the high E ring on as open strings. Only the bass note and the B-to-C move change. The idea is [[AI Wiki - Music - Guitar Chord Transitions]] in action: find what stays, and move what doesn't by the shortest route. ## When pop ignores the rule on purpose Songwriters use jumps for effect. A chorus that leaps up a fifth into its top note feels bigger than a smooth approach. A piano ballad can switch from a low spread voicing to a high close voicing on the chorus to make it open up. These are choices, not accidents. Know the smooth version first, then break it when the song needs it. Compare [[AI Wiki - Music - Common Chord Progressions]], where most of the famous four-chord loops can be voiced smoothly or with leaps with a very different effect. ## What to practise 1. Play C, F, G with the right hand in the nearest inversions. Then do the same in D, G, A and in G, C, D. 2. Play the ii-V-I guide-tone lines in the right hand in three keys (C, F, Bb) with the root in the left hand. 3. Sing the guide-tone line while playing it (3rd of ii, 3rd of V, 3rd of I). 4. On guitar, play the I-IV-V in a key with the smallest possible hand movement, and write down which fingers stay. 5. Pick a song you know and replace one chord with an inversion or a different shape that shares a note with its neighbours. ## Key Points - Voice leading: how each note of a chord moves to the next chord. - Keep common tones, move by step, use contrary motion against the bass. - Parallel fifths and octaves merge voices. Classical writing avoids them; rock and pop use them deliberately. - Guide tones (3rd and 7th) move by half step or not at all in a ii-V-I. - On piano use inversions; on guitar use shells and shapes on adjacent string sets. ## Open Questions - What are good bass-line voice-leading patterns? Bass has no instrument block yet (dsebastien/music-notation#27, open), so examples would need plain-text tab. - Which voice-leading ideas apply to fingerstyle arrangements, where the melody sits on top of a moving bass? - How much of the classical "no parallels" rule is worth teaching to a beginner playing popular songs? - Needs: a source for parallel triads in impressionist music and soul or gospel guitar, and for octave doubling as a production habit (neither Wikipedia page read covers them). The minor ii-V-i lines above are computed from the chords; no source read describes them yet. ## References - Wikipedia, "Voice leading": https://en.wikipedia.org/wiki/Voice_leading - Wikipedia, "Consecutive fifths": https://en.wikipedia.org/wiki/Consecutive_fifths - Wikipedia, "Contrary motion": https://en.wikipedia.org/wiki/Contrary_motion - Jazzify, "Guide Tones for Jazz Piano: Connect Chords with Less Motion": https://en.jazzify.jp/blog/jazz-piano-guide-tones/ ## Related - [[AI Wiki - Music - Piano Chord Inversions]] - [[AI Wiki - Music - Piano Voicings]] - [[AI Wiki - Music - Seventh Chords]] - [[AI Wiki - Music - Guitar Seventh Chord Voicings]] - [[AI Wiki - Music - Guitar Chord Transitions]] - [[AI Wiki - Music - Power Chords]] - [[AI Wiki - Music - Common Chord Progressions]] - [[AI Wiki - Music - Tension and Resolution]] - [[AI Wiki - Music - Modulation]] - [[AI Wiki - Music - Diminished and Augmented Chords]] - [[AI Wiki - Music - Triads]] - [[AI Wiki - Music - Jazz Music]] - [[AI Wiki - Music - Classical Music]] - [[AI Wiki - Music - Gospel Music]] - [[AI Wiki - Music - Slash Chords]]