## 12. Voice Leading

Voice leading is the horizontal side of harmony: instead of asking which chord comes next, it asks what each individual part does on the way there — what it holds, how far it moves, and which moves make two parts stop sounding like two.

Source: https://musictheory.center/course/voice-leading
Level: Intermediate · Harmony · 5 sections
Before this: Diatonic Harmony

### Voices, Not Chords

https://musictheory.center/course/voice-leading#voices-not-chords

> Play the first one: four chords, each one struck as a solid handful and lifted clean off before the next lands. Now play the second: the same four chords, in the same order, at the same speed. This time pick one note — the highest is easiest — and follow only that note from start to finish. One clip is four separate events. The other is four lines running at the same time. Which is which — and at the first change of the second clip, how many notes stay exactly where they are?

**Plays:** Four chords, grabbed and dropped (C4 E4 G4 F4 A4 C5 B4 D5) · The same four, played as four lines (C3 E3 G3 C4 F2 F3 A3 G2 D3 B3)

The second clip written out: four chords, each with four note heads, on a bass-clef staff. Read it downwards and you see four chords. Read any one row of the table across and you see something else — a short tune. The top line barely moves: it sits on the same note for the first two chords, dips a half step lower for the third and comes back for the last. The bottom line does the opposite, dropping a fifth and then climbing back in two moves. Those are four different shapes, and they are happening at once. That is the whole subject of this chapter, and it is invisible if you only read the page downwards.

| Part | First chord | Second | Third | Fourth | What it did |
| --- | --- | --- | --- | --- | --- |
| Soprano (top) | C4 | C4 | B3 | C4 | Stayed, fell a half step, came back |
| Alto | G3 | A3 | G3 | G3 | Up a whole step, back down, then stayed |
| Tenor | E3 | F3 | D3 | E3 | Up a half step, down a third, up a whole step |
| Bass (bottom) | C3 | F2 | G2 | C3 | Down a fifth, up a whole step, up a fourth |

**voice leading**

*also called*: part writing (British usage and most classroom teaching, where the four parts are "parts" rather than "voices")

**Definition.** Voice leading is the way each individual line in a piece of music moves from one chord to the next — what it holds on to, what it gives up, and how far it travels — as distinct from which chords are being played at all.

Up to now a chord has been a single object: a [stack of thirds](https://musictheory.center/course/chords#stacking-thirds) with a name. That is the vertical reading, and it is the one a [chord symbol](https://musictheory.center/course/chords#reading-chord-symbols) gives you. There is a second reading of exactly the same notes. Take a fixed number of lines — four is the usual laboratory — give each one a note of the first chord, and then ask each line separately where it goes next. Nothing about the harmony changes. What changes is that you now have four short tunes instead of one sequence of blocks, and the four tunes are what a listener actually follows.

You can hear the difference in the two clips because the ear is built to track continuity. In the blocked version every note leaps the same distance at the same instant, so there is nothing to follow and the ear hears four unrelated thumps. In the four-part version the top note holds still through the first change, which makes the ear treat the two chords as one connected event rather than two. **Continuity is a property of the lines, not of the chords**, which is why the same four chords can sound stitched together or dropped on the floor.

The word "voice" is a historical accident that stuck. The rules of this chapter were worked out for singers, and the four standard parts still carry choral names — soprano, alto, tenor, bass, top to bottom. Nothing requires actual voices. A string quartet has four; a guitarist fingering a chord has as many as they have fingers down; a pianist has two hands and about ten. The reasoning is identical in every case.

**Good to know**

- (Convention) Four parts is the teaching default, and there is nothing sacred about the number. It was chosen because four is the smallest texture that can state a [seventh chord](https://musictheory.center/course/chords#seventh-chords) completely, because it matches a choir, and because most of the surviving examples are Bach chorales, of which there are several hundred, all in four parts. Two-part and three-part writing follow the same reasoning with fewer constraints; orchestral writing follows it with many more.
- (Fact) A chord and a set of lines are two readings of one set of notes, not two different things. The second clip contains [C](https://musictheory.center/chord/c-maj), [F](https://musictheory.center/chord/f-maj), [G](https://musictheory.center/chord/g-maj) and [C](https://musictheory.center/chord/c-maj) — exactly the chords the first clip contains, in the same order. Every difference you can hear between the two comes from which note of each chord was given to which line, and nothing else.
- (Tendency — any texture where the parts share a timbre, which is where the effect is strongest: choral writing, string ensembles, keyboard textures. Orchestration can override it completely by giving an inner part a solo instrument, which is the subject of Chapter 18) A listener follows the outer parts — the highest and the lowest — far more closely than the ones in the middle. That is why the top line usually carries the tune and the bottom line usually carries the harmonic argument, and why an inner part can get away with motion that would sound clumsy on the outside.

**You already know this**

- Common progressions from Chapter 11 — I–IV–V–I is one of them, and this chapter is about what happens between its chords rather than which chords they are — https://musictheory.center/course/diatonic-harmony#common-progressions
- The stack of thirds from Chapter 10, which is the vertical reading this section sets a horizontal one beside — https://musictheory.center/course/chords#stacking-thirds

**Where this goes**

- Deciding which player or which instrument gets which of these lines — and how many lines a texture should have at all — is arranging, and it starts from exactly this reading — https://musictheory.center/course/orchestration

**In real music**

- J. S. Bach — “Jesu, Joy of Man’s Desiring (BWV 147)” — when the choir enters over the running accompaniment, try to follow the lowest singers rather than the sound as a whole — each of the four parts is a tune you could sing on its own
- Queen — “Bohemian Rhapsody” — the unaccompanied opening is sung as several separate overdubbed lines rather than struck as one chord, which is why the harmony seems to move even where the chord does not change

**Try it on your instrument:** Play any three-note chord on your instrument, then the chord a fourth above it, grabbing both in the same shape. Now play the same two chords again, but this time find a fingering for the second one that keeps at least one note exactly where it was in the first. Say out loud which note you kept.

**Check:** Two chords, one after the other. Did they share a note that stayed exactly where it was, or did every note move?

- One note stayed exactly where it was **(correct)** — Correct. The bottom note was common to both chords and never moved; the other two rose by a step each. That held note is why the two chords sound connected rather than adjacent — the ear takes an unchanged pitch as evidence that one thing is continuing.
- Every note moved — Every note moving is what the first clip at the top of this section does, and it is what makes those four chords sound like four separate events. Here the lowest note of the second chord was the same pitch as the lowest note of the first, and the movement was confined to the two notes above it.
- Two notes stayed where they were — Only one was held. These two chords have exactly one note in common, so one is the most that could have stayed. Two common tones happens between chords whose roots are a third apart — the next section has a pair of those.

### Smooth Motion

https://musictheory.center/course/voice-leading#smooth-motion

> Play both. Five chords each, the same five, in the same order. In the first clip nothing travels further than it has to: when a note belongs to the next chord as well, it simply stays. In the second, every chord is grabbed from scratch in its home shape, so nothing is ever kept. Before you read on, count how many of the four changes in the first clip leave at least one note sitting exactly where it was. The third clip runs the two settings end to end, which is the six bars of the staff below exactly as printed.

**Plays:** Five chords that keep what they can (C4 E4 G4 A4 F4 B3 D4) · The same five, each grabbed from scratch (C4 E4 G4 A4 C5 E5 F4 B4 D5) · The two settings end to end, as written (C4 E4 G4 A4 F4 B3 D4 C5 E5 B4 D5)

The two clips written out, the first three bars and then the last three, which the third clip above plays straight through. In the first three bars the note heads barely shift: most of them sit on the same line or space as the chord before, and the ones that move mostly go to the neighbouring line or space. In the last three bars the same five chords climb the page in a staircase and come back down, every head moving every time. Both sets of bars contain identical harmony. The table names the four ways two lines can move relative to each other, which is the vocabulary the rest of the chapter needs.

- **A common tone is a note two chords share** — [C](https://musictheory.center/chord/c-maj) and [Am](https://musictheory.center/chord/a-m) share C4 and E4; [Am](https://musictheory.center/chord/a-m) and [F](https://musictheory.center/chord/f-maj) share A4 and C4; [F](https://musictheory.center/chord/f-maj) and [G](https://musictheory.center/chord/g-maj) share nothing at all.
- **Two triads a third apart share two notes** — Roots a third apart give two common tones, roots a fifth apart give one, roots a step apart give none — which is why a step-apart change is the one where every part has to move.

| Motion | What the two parts do | Example |
| --- | --- | --- |
| Parallel | Both move the same direction by the same number of scale steps, so the gap between them stays the same size — two parts in thirds stay in thirds, even though the key makes some of those thirds major and some minor | Two singers in thirds all the way through a chorus |
| Similar | Both move the same direction by different distances, so the gap widens or narrows | The bottom of a chord falling a fifth while the top falls a step |
| Contrary | They move in opposite directions | The second change of the four-part clip in the previous section: the bottom part rises a step while the three parts above it fall |
| Oblique | One holds its note while the other moves | The first change in the first clip: the bottom two notes stay and only the top moves |

**smooth voice leading**

**Definition.** Smooth voice leading is writing in which each part moves as little as the harmony allows: it holds any note the next chord also contains, and where it must move it moves to the nearest available note rather than to the one that happens to sit in the same fingering.

The rule has two halves and they are worth separating. The first half is **hold the common tones**: if the chord you are leaving and the chord you are going to share a note, give that note to a part and leave it alone. The second half is **move everything else by step**: of the notes that do have to move, send each one to the nearest member of the next chord instead of to the note in the same position in the stack. Between chords a third apart you will find two common tones and the rest of the work is trivial; between chords a step apart — [F](https://musictheory.center/chord/f-maj) to [G](https://musictheory.center/chord/g-maj), the third change in the first clip — there is nothing to hold and every part has to move, which is exactly where the effort goes.

That is the default, not a law, and the reason for it is practical. Small moves are easier to sing, easier to play, and easier to follow. A line that leaps constantly costs the listener attention, so leaps become expensive and therefore expressive: save them and a single wide jump in an inner part becomes an event. Spend them everywhere and nothing registers.

The four names in the table describe the relationship between any two parts at any one change, and they are the vocabulary the next section needs. Note that they are relative: at a single change one pair of parts can be in contrary motion while another pair is oblique. You do not describe a whole passage as "contrary"; you describe what two named parts did between two named chords.

**Good to know**

- (Convention) The four motion types — parallel, similar, contrary and oblique — are standard across every tradition that teaches counterpoint, and the only common variation is that some writers fold parallel motion into similar motion and end up with three. Where that is done, "similar" covers everything moving the same way and "parallel" is reserved for the case where the distance is also unchanged.
- (Fact) How many notes two [triads](https://musictheory.center/course/chords#the-four-triads) share is fixed by how far apart their roots are, not by taste. Roots a third apart share two notes — [C](https://musictheory.center/chord/c-maj) and [Am](https://musictheory.center/chord/a-m) have C4 and E4 in common. Roots a fifth apart share one. Roots a step apart share none, so at a step-apart change every part must move whether you want it to or not.
- (Tendency — sung and melodically conceived parts in essentially all Western repertoire. Instrumental writing that is idiomatic rather than melodic — a keyboard left hand jumping between a low root and a mid-register chord, an arpeggiated guitar accompaniment, a walking bass — is judged by other criteria entirely) Where a choice exists, the smallest move is the default and anything larger has to earn its place. Writers break it constantly — a leap up to a high note is one of the oldest ways to make a [phrase](https://musictheory.center/course/melody#phrase-antecedent-consequent) peak — but they break it at chosen moments, against a background of stepwise motion that makes the break audible.

**You already know this**

- Half steps and whole steps from Chapter 5, which are the two distances "by step" means and the two a smoothly written part mostly travels — https://musictheory.center/course/intervals#half-steps-and-whole-steps
- The seven diatonic chords from Chapter 11, which is where you look to find out what the next chord contains and therefore what can be held — https://musictheory.center/course/diatonic-harmony#chords-in-a-key

**Where this goes**

- The top line of a smoothly written texture is a tune, and everything this section says about how far a part should travel applies to melody writing directly — https://musictheory.center/course/melody

**In real music**

- W. A. Mozart — “Ave Verum Corpus, K. 618” — the opening phrase: the four sung parts move almost entirely by step, and it is the standard classroom example of writing that never jumps where it can walk
- The Beatles — “Blackbird” — the guitar keeps one string ringing on the same note throughout while the lines above and below it walk away from it and back — the fourth row of the table, held for a whole song

**Try it on your instrument:** Take any four-chord [progression](https://musictheory.center/course/diatonic-harmony#common-progressions) you can already play and write out, for each chord, which notes it has in common with the one before it. Then play the progression again and deliberately keep every one of those shared notes in the same place, changing your fingering wherever you have to. Do it once more with no shared notes kept and compare.

**Check:** Three chords from the first clip, in order, stopping before the fourth. In the clip the fourth chord follows straight on. Predict what the highest note does on that change — not what a rule would force, but what this particular setting actually did.

- It moves down by a step **(correct)** — Correct. The highest note falls a whole step on to a note the next chord contains. These two chords are a step apart, so nothing could be held and every part had to move; this setting sends the top part downward, so the outer parts draw closer together as the phrase closes.
- It moves up by a step — A reasonable answer, and the reason the question asks what this setting does rather than what the rule forces: the note a step above the one the top part was holding belongs to the next chord too, so up a step was just as small a move and just as available. The setting took the other one. Listen again and the highest note falls.
- It stays exactly where it is — Staying is the first thing to try, and here it is not on offer: these two chords are a step apart, which is the one case that guarantees no common tones. Look back at the fact panel — roots a step apart share nothing, so nothing can be held.
- It leaps further than a step — A leap is what the second clip does at every change, and it is what this section argues against wherever a step will do. Two different steps were available here, one up and one down, and the setting took the one going down.

### Parallels, and Why They Are Avoided

https://musictheory.center/course/voice-leading#parallels-and-why-they-are-avoided

> Play the first two. Each is two notes climbing a scale together, and the clips differ only in how far apart the two are held — a fifth in one, a third in the other. Something happens to one of the two pairs that does not happen to the other. Which pair, and what? Now play the last two: the same four chords twice over, once built out of pairs held that way and once with every part going its own direction. Which of the last two keeps four separate things audible?

**Plays:** Two notes climbing, held a fifth apart (C4 G4 D4 A4 E4 B4 F4 C5 D5) · Two notes climbing, held a third apart (C4 E4 D4 F4 G4 A4 B4) · Four chords built from two notes each (C3 G3 C4 F3 F4 D4 G4) · The same four chords, every part on its own path (C3 E3 G3 C4 F2 F3 A3 G2 D3 B3)

The first clip written out: five pairs of note heads, four of them a beat each and the last given the whole of its bar to ring in, and in every pair the two heads are the same distance apart on the page. The whole shape slides upwards without ever changing. That picture is the definition — two parts moving the same direction by the same distance — and what makes this particular distance a problem is that it is one of the two most blended distances there are. The table sorts the distances by how a tradition of four-part writing treats each one, and by where music uses it deliberately anyway.

| Distance between the two parts | Treated as | Why | Used on purpose in |
| --- | --- | --- | --- |
| Unison | Avoided in succession | Two parts on the same pitch are one part; the texture loses a line and does not get it back | Orchestral doubling, where the point is a single reinforced colour |
| [Octave](https://musictheory.center/interval/octave) | Avoided in succession | The blend is almost total, so two parts an octave apart and moving together read as one part played louder | Piano and guitar octave doubling, and almost every bass-plus-synth pop production |
| [Perfect Fifth](https://musictheory.center/interval/perfect-fifth) | Avoided in succession | The next most blended distance after the octave, and the same collapse happens a little less completely | Power chords, medieval organum, and the fifths of a great deal of rock and metal |
| Thirds and sixths | Encouraged | Consonant enough to sound good together and blended nowhere near enough to fuse, so both parts stay audible | Everywhere — two singers in thirds is the commonest harmony in popular music |
| [Perfect Fourth](https://musictheory.center/interval/perfect-fourth) | Allowed between upper parts | A fourth against the lowest part is treated as a dissonance in this tradition, but between two upper parts it raises no objection | Parallel fourths are the standard sound of a quartal jazz voicing and of a great deal of film scoring |

**parallel fifths**

*also called*: consecutive fifths (British usage, and the older term in both traditions), consecutive octaves (British usage, for the same thing at the octave)

**Definition.** Parallel fifths are two parts that are a perfect fifth apart and then move to another perfect fifth in the same direction — and parallel octaves are the same thing an [octave](https://musictheory.center/course/pitch-and-notes#the-octave) apart. In four-part common-practice writing both are avoided, deliberately and systematically, and almost nothing else in that tradition is policed as strictly.

The reason is not that the sound is ugly. It is that the sound is **too well blended**. The octave and the perfect fifth are the two most [consonant intervals](https://musictheory.center/course/intervals#consonance-and-dissonance) there are: their overtones coincide almost completely, so the ear fuses them into one pitch with a thickened colour rather than hearing two. As long as the distance keeps changing, the ear can pull the parts apart again. Keep the distance fixed across a change and there is nothing left to pull apart — the two parts stop being two parts and collapse into one. In a texture whose entire premise is four independent lines, losing one of them for a bar is a structural failure, which is why the tradition treats it as a mistake rather than a preference.

That premise is not universal, and this is the part that classroom teaching routinely leaves out. **Parallel fifths are a rule inside one tradition, not an acoustic fault.** The earliest written polyphony in Europe, ninth-century organum, consists of parallel fifths and fourths from beginning to end, and it was the normal sound of church music for two centuries. The power chord — a root and its fifth and nothing else — is the foundation of hard rock, punk and metal precisely because moving it around in parallel gives you weight without harmonic colour. Debussy wrote strings of parallel fifths on purpose to get a sound that was deliberately not tonal. When a modern engraver or arranger uses them, the fusion is usually the point.

So the working question is never "are there parallel fifths here". It is "am I writing in a texture where independent lines are the point". If yes, check for them. If the texture is a guitar riff or a doubled bass line, the check does not apply and never did.

**Good to know**

- (Fact) Two parts moving in parallel perfect consonances fuse into one. The [Octave](https://musictheory.center/interval/octave) and the [Perfect Fifth](https://musictheory.center/interval/perfect-fifth) share most of their overtones with the note underneath, so the ear reads C4 with G4 above it as a single thickened C rather than as two pitches. Changing the distance between two parts is what keeps them separately audible; holding it fixed is what removes them from the count.
- (Constraint — four-part common-practice writing (species counterpoint, chorale-style exercises). Outside that tradition the rule simply does not apply: organum is built from parallel fifths, power chords are parallel fifths by definition, and a great deal of rock, film and impressionist writing uses them as a colour) Parallel fifths and parallel octaves between any two parts are forbidden, and the prohibition is absolute: it applies between the outer parts and between inner ones, on strong beats and weak, and whether the parts move by step or by leap. The related near-misses have their own names and their own weaker rules — **hidden** or **direct** fifths and octaves, where two parts arrive at a fifth or an octave by similar motion rather than already being in one, are restricted only between the outer parts and only when the upper of them moves by leap.
- (Convention) Thirds and sixths in parallel are not merely tolerated but recommended, and the reason is the same acoustics read the other way: they are consonant enough to sound good and blended little enough that both parts stay audible. Two singers in thirds is the default harmony of popular music on every continent, and a chain of parallel sixths is one of the standard fillers of classical part writing.

**You already know this**

- Consonance from Chapter 5 — the octave and the perfect fifth are the two most blended intervals there are, which is the whole reason this rule exists — https://musictheory.center/course/intervals#consonance-and-dissonance
- Number and quality from Chapter 5: "perfect" is the quality the two forbidden distances share, and thirds and sixths — which are never forbidden — are exactly the intervals that come in major and minor instead — https://musictheory.center/course/intervals#number-and-quality

**Where this goes**

- Deliberate doubling at the octave and the fifth is a colour an arranger reaches for constantly, and knowing what it costs in independence is what makes it a choice rather than an accident — https://musictheory.center/course/orchestration

**In real music**

- Nirvana — “Smells Like Teen Spirit” — the four-chord riff is played as root-and-fifth pairs, so both notes move by the same distance at every change — the exact motion four-part writing forbids, used here for weight
- The Kinks — “You Really Got Me” — the riff slides the same two-note shape up and down the neck without ever changing its width; the fusion is the sound of the record

**Try it on your instrument:** On your instrument, play a root and the note a fifth above it, then slide the whole shape up one step and play it again, and again. Now play the same three chords keeping the lower note where it is for as long as you can and moving only the upper one. The first version thickens; the second stays as two things. Try both with the notes a third apart instead and notice that the effect does not appear.

**Check:** Two notes, sounding five times in a row. What did they do relative to each other?

- They moved in opposite directions **(correct)** — Correct. The lower note climbed and the upper note descended, so the gap between them narrowed at every step and was never twice the same. That constantly changing gap is what keeps two notes audible as two, and it is why this motion is the one the tradition considers strongest.
- They moved the same direction and stayed the same distance apart — That is what the first clip at the top of this section does, and the giveaway is that the gap never changes: once you have heard the first pair you can predict the width of every pair after it. Here the two notes converged — by the last pair they were much closer together than at the start.
- One stayed still while the other moved — Oblique motion means one part holds a single pitch while the other moves around it, so one of the two notes would have repeated five times. Both notes changed at every step here; what made them sound like two separate things was that they changed in opposite directions.

#### Where the rule came from, and why it outlived its reason

Parallel fifths were not forbidden because somebody disliked them. They were forbidden because they had been the normal sound of European church music for roughly two hundred years and then went out of fashion. Ninth- and tenth-century organum harmonised plainchant by doubling it at the fifth or the fourth throughout; by the fourteenth century that texture sounded archaic, and composers who wanted the newer independent-line sound had to make a point of avoiding the older one. The prohibition is the fossil of that stylistic change.

It survived because it turned out to be a reliable teaching device. A student who has been made to hunt for parallel fifths for a term has, as a side effect, learned to read music horizontally — to look along each part instead of down each chord — and that habit is the actual point of the exercise. The rule is a proxy for a skill.

Which is why the sensible modern position is to learn it properly and then hold it lightly. Know what parallel fifths sound like; know why they cost you a line; know that the strict form of the rule belongs to one repertoire. Then use them where the fusion is what you want, which for anyone writing with a distorted guitar is most of the time.

### Bass Lines and Inversions

https://musictheory.center/course/voice-leading#bass-lines-and-inversions

> Play both. The same eight chords, in the same order, at the same speed, and the top three notes of every chord are identical between the two clips. Only the lowest note of each chord differs. In one clip that lowest note jumps from chord to chord; in the other it does something else entirely. Which is which — and which of the two sounds as though it is going somewhere rather than restarting eight times?

**Plays:** Eight chords, each sitting on its own root (C3 C4 E4 G4 G2 D4 B4 A2 A4 F2 F4 D2 A3 B3) · The same eight with the lowest note walking down (C3 C4 E4 G4 B2 D4 B4 A2 A4 G2 F2 F4 E2 D2 A3 B3)

The lowest line of the second clip on its own, on a bass-clef staff: seven note heads stepping down one line or space at a time, and then a leap back up at the end. Written out like that it is obviously a tune — you could sing it — and it is the reason the second clip holds together. The harmony above it never changed. The table gives the eight chords with the note each one was made to sit on and how that was done; three of the eight are turned over so that a note other than the root is at the bottom.

- **Root position, first inversion, second inversion** — The root at the bottom, the third at the bottom, the fifth at the bottom. [C](https://musictheory.center/chord/c-maj) gives C3 E3 G3, then E3 G3 C4, then G3 C4 E4 — the same three notes each time.
- **A slash names the bottom note** — C/E is read "C over E": a [C](https://musictheory.center/chord/c-maj) chord with E2 underneath it. The letter before the slash is the chord; the letter after it is whatever the lowest part is playing.

| Chord | Lowest note | Written | What it does to the line |
| --- | --- | --- | --- |
| [C](https://musictheory.center/chord/c-maj) | C3 | C | Starts at the top of the descent |
| [G](https://musictheory.center/chord/g-maj) | B2 | G/B | Turned over so the third is at the bottom: one step down |
| [Am](https://musictheory.center/chord/a-m) | A2 | Am | Already a step down in root position |
| [C](https://musictheory.center/chord/c-maj) | G2 | C/G | Turned over so the fifth is at the bottom: one step down |
| [F](https://musictheory.center/chord/f-maj) | F2 | F | Already a step down in root position |
| [C](https://musictheory.center/chord/c-maj) | E2 | C/E | Turned over so the third is at the bottom: one step down |
| [Dm](https://musictheory.center/chord/d-m) | D2 | Dm | Already a step down in root position |
| [G](https://musictheory.center/chord/g-maj) | G2 | G | Back to the root, leaping up a fourth to close the phrase |

**bass line**

**Definition.** A bass line is the lowest part of a texture read horizontally — the tune the bottom notes make when you follow them across a progression instead of reading each chord downwards. It is the part a listener tracks most closely after the [melody](https://musictheory.center/course/melody#what-makes-a-melody), and it is the one that most decides whether a sequence of chords sounds connected.

The lowest note does two jobs at once, and they can conflict. Vertically it decides the chord's **inversion**: put the root at the bottom and the chord sounds settled and final, put the third at the bottom and it sounds lighter and in transit, put the fifth at the bottom and it sounds unstable and asks to move on. Horizontally it is a line, and it wants what every line wants — to move by step, to have a shape, to arrive somewhere. Playing every chord in [root position](https://musictheory.center/course/chords#inversions) gives you the strongest vertical reading and, usually, the worst horizontal one: the bottom part becomes a series of leaps between roots.

Inversions are how the conflict is resolved. Because the inversion is decided by which note is at the bottom and nothing else, you can choose the bottom note to suit the line and let the inversion fall out of that choice. That is the whole of the second clip: three of its eight chords are turned over so that the bottom part descends a scale, C3 down to D2, without once repeating a note. The harmony is untouched. Only the bottom of each chord moved, and the passage stopped sounding like eight events and started sounding like one. Both clips are keyboard settings rather than chorale ones, and throughout they double that bottom note one or two [octaves](https://musictheory.center/course/pitch-and-notes#the-octave) above itself — the deliberate octave doubling the previous section listed among the uses this motion is actually put to, rather than the lapse a four-part exercise would call it.

The descending stepwise bass is common enough to have become a genre in itself. It is the shape of a Baroque lament, of Pachelbel's Canon, of "A Whiter Shade of Pale" and of a large fraction of the ballads written since. Its opposite — a bass that climbs by step — pushes rather than settles, which is why it turns up under a rising [phrase](https://musictheory.center/course/melody#phrase-antecedent-consequent) and almost never under a final one.

**Good to know**

- (Fact) The inversion of a chord is decided by the lowest sounding note and by nothing else. [C](https://musictheory.center/chord/c-maj) with E2 at the bottom is a first-inversion C chord however the notes above it are arranged, and rearranging those upper notes changes the voicing without changing the inversion at all.
- (Convention) Two notations name the same thing. [Chord symbols](https://musictheory.center/course/chords#reading-chord-symbols) use a slash — C/E, G/B, Am/C — where the letter after the slash is the lowest note. Classical analysis uses figured-bass numbers after the numeral instead: a plain numeral is root position, a superscript 6 is first inversion, and 6/4 is second inversion, so I with the third at the bottom is written I6. The numbers count intervals above the lowest note, which is why first inversion is "6" — the root sits a sixth above the third.
- (Tendency — tonal Western repertoire from the Baroque onward, and popular music descended from it. A walking jazz bass leaps constantly by design, and much dance and electronic production puts the root under every chord deliberately so that nothing competes with the kick) Stepwise motion in the lowest part binds a progression together; leaping motion separates it into units. That is why a descending stepwise bass reads as one long relaxing gesture and a bass that leaps between roots reads as a sequence of distinct arrivals — and why the second is the right choice when arrivals are what you want.

**You already know this**

- Inversions from Chapter 10 — the same notes with a different one at the bottom — which turn out to be the tool for shaping the lowest line rather than a curiosity about chord spelling — https://musictheory.center/course/chords#inversions
- The authentic cadence from Chapter 11, whose strength depends on the lowest note falling a fifth — which is exactly the leap you do not want in the middle of a phrase and do want at the end of one — https://musictheory.center/course/diatonic-harmony#cadences

**Where this goes**

- A bass that walks down chromatically rather than by scale steps needs chords from outside the key to sit on, and supplying them is one of the commonest uses of chromatic harmony — https://musictheory.center/course/advanced-harmony

**In real music**

- Procol Harum — “A Whiter Shade of Pale” — the organ walks its lowest note down a step at a time under the whole of each verse; the chords above it are ordinary, and the descent is what you actually remember
- The Beatles — “Dear Prudence” — the guitar repeats the same figure on the top strings while the lowest note steps down underneath it — the upper part is static and the bottom one carries the motion
- J. S. Bach — “Air on the G String (from the Orchestral Suite No. 3)” — the bass walks in even notes from the first bar to the last, and the long [melody](https://musictheory.center/course/melody#what-makes-a-melody) above it is written against that walk rather than over the chords

**Try it on your instrument:** Play a four-chord [progression](https://musictheory.center/course/diatonic-harmony#common-progressions) you know in [root position](https://musictheory.center/course/chords#inversions) and write down the lowest note of each chord. Then try to rewrite that list so the notes descend or ascend by step, rearranging each chord so that the note you want ends up at the bottom. Play both versions back to back and decide which one you would put under a verse.

[Name a chord from its bass upward and see the slash it earns](https://musictheory.center/tools/chord-identifier?n=B2%2CD4%2CG4)

**Check:** Eight chords. Listen only to the lowest note of each one and ignore everything above it. What did that lowest note do?

- It stepped down one note at a time, then jumped up at the end **(correct)** — Correct. Seven steps down in a row and then a leap back up to close. Three of those eight chords had to be turned over to make it happen, so that a note other than the root was at the bottom — and none of the harmony above changed to allow it.
- It jumped between the roots of the chords — That was the other clip at the top of the section, where every chord sat on its own root and the bottom part leapt a fourth or a fifth at almost every change. Play the two back to back listening only to the lowest note and the difference is unmistakable.
- It stayed on the same note throughout — A bottom note that holds one pitch through several chords is called a pedal, and it is a real and useful device — but it is not what happened here. Try humming along with the lowest note: your voice will keep descending.
- It stepped up one note at a time — The motion was stepwise, which is the important half of the answer, but the direction was down. An ascending stepwise bass pushes a phrase forward and is used under rising material; a descending one relaxes, which is why it is the shape of almost every lament ever written.

### Non-Chord Tones

https://musictheory.center/course/voice-leading#non-chord-tones

> Play the first two: a short tune over one unchanging chord, then the same tune with two extra notes threaded between its notes. Then play the last two: two chords with nothing carried across, then the same two chords with one note from the first left hanging into the second before it drops into place. In each pair one clip contains notes that do not belong to the chord sounding underneath. Find them — and decide whether they sound like mistakes.

**Plays:** A tune over one chord, three notes only (C3 E3 G3 C5 E5 G5) · The same tune with two extra notes threaded in (C3 E3 G3 C5 D5 E5 F5 G5) · Two chords with nothing carried across (C3 E3 G3 C5 G2 D3 B4) · The same two chords with one note left hanging (C3 E3 G3 C5 G2 D3 B4)

The tune from the second clip on its own: five note heads climbing one line or space at a time, the last of them ringing through a bar of its own. The first, third and fifth of them belong to the chord held underneath. The second and fourth do not — they are simply the notes the scale supplies between them, and they last a fraction of a second on the way past. Play the same five notes slowly against the chord and the two odd ones sound harsh; play them at speed and they sound like motion. The table names the six standard ways a note that does not belong to the chord can get into a line, sorted by how it is approached and how it is left.

| Name | Approached by | Left by | On or off the beat |
| --- | --- | --- | --- |
| Passing tone | Step | Step, continuing the same direction | Usually off the beat |
| Neighbour tone | Step | Step, back to the note it came from | Usually off the beat |
| Suspension | Held over from the previous chord | Step down, on to a note of the new chord | On the beat — that is what makes it bite |
| Appoggiatura | Leap, usually upward | Step, usually in the opposite direction | On the beat |
| Escape tone | Step | Leap, in the opposite direction | Off the beat |
| Anticipation | Step or leap | Nothing — it holds, and the chord arrives underneath it | Just before the beat |

**non-chord tone**

*also called*: non-harmonic tone (much North American theory writing, for the same thing)

**Definition.** A non-chord tone is a note that sounds against a chord it does not belong to: not a wrong note and not a change of harmony, but a note borrowed from the scale, or from outside it, that sits between two notes of the chord and resolves on to one of them.

It is defined entirely by what happens on either side of it. The note itself is not special — D5 over a [C](https://musictheory.center/chord/c-maj) chord is only a passing tone because of how it was reached and how it was left. Approach it by step and leave it by step in the same direction and it is a passing tone. Approach it by step and go back where you came from and it is a neighbour. Hold it over from the previous chord so that it becomes a [dissonance](https://musictheory.center/course/intervals#consonance-and-dissonance) the moment the harmony changes, then step down out of it, and it is a suspension. **The catalogue in the table classifies journeys, not pitches**, which is why the same note can be three different things in three different bars.

What they are all for is motion. A line that touches only chord members has to leap, because the members of a [triad](https://musictheory.center/course/chords#the-four-triads) are thirds apart; threading the scale notes between them turns a series of leaps into a line you can sing. The dissonance is not an unfortunate side effect — it is the engine. A note that does not belong wants to resolve, so the ear leans forward, and the moment of resolution is a small arrival. String enough of those together and you have a [melody](https://musictheory.center/course/melody#what-makes-a-melody) instead of an arpeggio.

Two of the six carry most of the expressive weight. The suspension is the one you can hear from across a room: because it lands **on** the beat, the dissonance arrives at the strongest moment in the bar and the resolution a beat later feels like a sigh. The appoggiatura is its more violent cousin — leapt into rather than held over, so the dissonance appears from nowhere — and it is what a songwriter reaches for on the emotional peak of a chorus.

**Good to know**

- (Convention) A non-chord tone is classified by its approach and its departure, not by which note it is. The same D5 over a held [C](https://musictheory.center/chord/c-maj) is a passing tone when it is walked into and walked out of in one direction, a neighbour when the line returns to where it started, and an escape tone when it is stepped into and then leapt away from.
- (Convention) The names are not stable across traditions and the disagreements are worth knowing. What this book calls a neighbour tone is an auxiliary note in British teaching; the escape tone is still often called an échappée; and a dissonance approached by leap on a strong beat is an appoggiatura to most writers but an "accented incomplete neighbour" to some. A suspension that resolves upward rather than downward gets its own name again — a retardation.
- (Tendency — common-practice classical writing and the popular song descended from it, which is where the catalogue was built. Blues, jazz and modal writing routinely sound the same notes as stable chord members — a ninth or an eleventh that never resolves at all — so the category itself dissolves once [extensions](https://musictheory.center/course/chords#extensions-a-first-look) are in normal use) A non-chord tone resolves by step, and almost always downward. The ear predicts the resolution well enough that a composer can delay it, stack another dissonance on top of it, or resolve it somewhere unexpected and be certain the effect will register.

**You already know this**

- Diatonic chords from Chapter 11: a note is a non-chord tone only relative to the chord underneath it, so you have to know what that chord contains before you can say anything is outside it — https://musictheory.center/course/diatonic-harmony#chords-in-a-key
- The major scale from Chapter 7, which supplies the notes a passing tone passes through — the chord takes every other degree and these are the ones it skipped — https://musictheory.center/course/scales#the-major-scale
- Suspended chords from Chapter 10 — sus4 and sus2 — which are the suspension written into the chord symbol itself instead of left as a passing event — https://musictheory.center/course/chords#reading-chord-symbols

**Where this goes**

- Choosing which notes of a tune land on the chord and which decorate it is most of what melody writing consists of, and the catalogue here is the list of options — https://musictheory.center/course/melody
- A passing tone from outside the key is the smallest possible piece of chromaticism, and harmonising one is how a chromatic chord usually gets into a progression in the first place — https://musictheory.center/course/advanced-harmony

**In real music**

- Johann Pachelbel — “Canon in D” — listen for the places where one violin holds its note through a chord change and then steps down on to the new chord a beat later — that hold-and-fall is the suspension, and the piece is full of them
- Adele — “Someone Like You” — the chorus is the most cited pop example of the appoggiatura: the vocal lands on a note that clashes with the chord underneath and then falls a step on to one that belongs to it

**Try it on your instrument:** Hold a chord on your instrument, or loop it in your software, and play a line over it that uses only notes of the chord. Then play the same line again filling in the scale notes between them. Finally, play two chords and hold one note of the first one into the second for a beat before letting it fall a step. Say out loud, each time, which notes did not belong.

**Check:** Two chords. On the second one, a note left over from the first stayed where it was for a moment and then moved. What did it do when it moved?

- It fell by a step on to a note of the new chord **(correct)** — Correct. The top note was held over from the first chord, which made it a dissonance the moment the second chord arrived, and then it fell a half step on to a note the second chord actually contains. Held over, dissonant on the beat, resolved downward by step: that is a suspension, and it is the third row of the table.
- It rose by a step on to a note of the new chord — Upward is the direction a suspension does not usually take, and when it does it is called a retardation instead and sounds noticeably less settled. Play the clip again and sing along with the top note: your voice drops at the resolution.
- It leapt away to a note further off — A leap away from a dissonance is what an escape tone does, and the effect is completely different — it leaves the tension unresolved and moves on. Here the tension was resolved, and by the smallest possible distance, which is what made the second chord sound like it finally arrived.
- It never moved at all — It did stay, but only for a moment. Listen to the very end of the second chord: the top note moves while the chord underneath it holds. That delayed move is the entire point of the device — everything else arrives on time and one note arrives late.

**Check:** A short rising line over one unchanging chord. Some of its notes belong to the chord and some do not. How were the ones that do not belong approached and left?

- Stepped into and stepped out of, continuing the same direction **(correct)** — Correct. The line climbed without ever changing direction, so each note that did not belong was reached by a step and left by a step the same way — the definition of a passing tone, and the first row of the table. It is the commonest of the six by a wide margin.
- Stepped into and then returned to the note just before them — A neighbour tone goes away and comes straight back, so the line would have turned round each time. This one never turned round: it climbed from the bottom note to the top without reversing once, which is what makes these passing tones rather than neighbours.
- Leapt into and stepped out of — A dissonance leapt into and stepped out of is an appoggiatura, and it lands hard because it appears from nowhere on a strong beat. Nothing here leapt at all — every note was one scale step from the one before it.
- Every note belonged to the chord — Three of the five notes belonged to the chord and two did not. Play the first clip at the top of the section, which really does use chord notes only, and then this one: the extra two are the ones that turned a set of leaps into something you could sing.

### Key Takeaways

https://musictheory.center/course/voice-leading#key-takeaways

- Voice leading is the horizontal reading of harmony: what each part does between two chords, as opposed to which chords are played.
- The default rule has two halves — hold any note the next chord also contains, and move everything else to the nearest available note.
- How many notes two triads share is fixed by how far apart their roots are: a third apart gives two common tones, a fifth apart gives one, a step apart gives none.
- Two parts can move in parallel, similar, contrary or oblique motion, and the description always applies to a named pair of parts across a named change.
- Parallel fifths and octaves are forbidden in four-part common-practice writing because perfect consonances fuse and the texture loses a line, not because the sound is bad.
- Outside that tradition the same motion is a deliberate colour: organum, power chords and a great deal of rock are built from it.
- A chord’s inversion is decided by its lowest note alone, which is what lets inversions be chosen to give the bottom part a stepwise line.
- A descending stepwise bass relaxes a progression and an ascending one drives it, which is why laments descend and build-ups climb.
- A non-chord tone is defined by how it is approached and left rather than by which note it is, and the six standard kinds are the passing tone, neighbour tone, suspension, appoggiatura, escape tone and anticipation.

### Questions

**What is voice leading?**

Voice leading is how each individual part moves from one chord to the next, rather than which chords are chosen. Good voice leading holds any note two chords share, moves the rest by the smallest available distance, and keeps the parts independent enough that a listener can follow each one separately.

**Why are parallel fifths avoided?**

Because the perfect fifth blends so completely that two parts moving in fifths fuse into a single thickened sound, and a texture built on independent lines loses a line. It is a rule of four-part common-practice writing, not an acoustic fault: organum, power chords and most rock use parallel fifths deliberately.

**What is a non-chord tone?**

A note sounding against a chord it does not belong to, borrowed from the scale to connect two chord notes. It is classified by approach and departure, not by pitch: stepped into and out of in one direction it is a passing tone, and held over from the previous chord it is a suspension.

**What is a suspension in music?**

A note held over from the previous chord so that it becomes a [dissonance](https://musictheory.center/course/intervals#consonance-and-dissonance) the moment the new chord arrives, then resolved downward by step on to a note the new chord contains. Because it lands on the beat, the tension falls on the strongest moment in the bar and the resolution feels like a release.

**How do inversions make a bass line smoother?**

A chord’s [inversion](https://musictheory.center/course/chords#inversions) is decided by its lowest note alone, so you can choose that note to suit the line and let the inversion follow. Turning three chords over is enough to make a bass walk down a scale instead of leaping between roots, with no change to the harmony above it.

**What are the four types of motion between two parts?**

Parallel motion moves both parts the same direction by the same distance. Similar motion moves them the same direction by different distances. Contrary motion moves them in opposite directions, which keeps them most clearly separate. Oblique motion holds one part still while the other moves around it.

### Other languages

- https://musictheory.center/course/voice-leading/llms.txt
- https://musictheory.center/fr/cours/conduite-des-voix/llms.txt
- https://musictheory.center/es/curso/conduccion-de-voces/llms.txt