Music theory · 6 min read

Harmony and voice leading, the basics

Chords are only half the story. Voice leading is how each note moves to the next, and it is what makes a progression sound smooth rather than merely correct.

2026-06-08

A chord is four notes, not one object

Write C major then G major and you have named two chords. But C major is the notes C, E and G, and G major is the notes G, B and D, and the question that matters is which note goes where. If the top voice jumps from G down to D while the bass leaps from C up to G and the inner parts scramble, the progression is technically correct and sounds clumsy.

Think of a four-part texture as four singers. Each has a range, each has to breathe, and each wants a line they can sing without lurching. Once you picture four people rather than a sequence of stacked shapes, most of the rules stop being arbitrary.

The standard voices from top to bottom are soprano, alto, tenor and bass. The bass is special: it determines the inversion and carries most of the harmonic weight. The soprano is special too, because listeners track the top line as the melody. The two inner voices exist mainly to complete the harmony without drawing attention, and their job is to move as little as possible.

The three working principles

First, keep common tones. If two consecutive chords share a note, leave that note in the same voice at the same pitch. C major and A minor share C and E; keeping both in place means only one voice has to move at all, by one step from G to A. This is why that progression sounds so soft.

Second, move the other voices by the smallest interval available. Prefer a step to a third, and a third to a leap. This is not about timidity: small motion is what makes the ear perceive continuity rather than a series of unrelated events.

Third, resolve tendency tones. Some notes carry a strong expectation of where they go next. The leading note, the seventh degree of the scale, pulls up to the tonic. The seventh of a dominant seventh chord pulls down by step. In G7 moving to C major, the B wants to rise to C and the F wants to fall to E. Honour those two resolutions and the chord change works almost regardless of what else happens.

The prohibitions, and the reason behind them

Parallel fifths and parallel octaves are avoided in common-practice writing because they collapse two voices into one. If the bass moves C to D and the tenor moves G to A, those two voices have been a perfect fifth apart throughout and the ear stops hearing them as separate parts. In a four-part texture that is a real loss. In rock guitar and in medieval organum it is the whole point, which tells you that the rule is stylistic, not moral.

Voice crossing, where an inner voice goes above the one nominally over it, muddles the texture and is avoided for the same reason. Large leaps in the inner voices are avoided because they draw attention to a part that should be invisible. Spacing between adjacent upper voices is usually kept within an octave, though the gap between bass and tenor can be wider, because low notes crowded together sound muddy.

That last point is acoustic rather than conventional. The harmonic series is widely spaced at the bottom and closely spaced at the top, so a third played low sounds thick and indistinct while the same third two octaves higher sounds clean. Any arranger who has voiced a chord badly in the bass register has learned this the hard way.

Voice leading on instruments that will not let you choose

This is where the accordion gets interesting. The Stradella left hand gives you a chord per button, in a voicing chosen by the manufacturer, usually compact and in the middle of the range. You cannot control which note is on top, cannot keep a common tone deliberately, and cannot avoid parallels. The instrument does its own voice leading and does it the same way every time.

The practical result is that Stradella accompaniment is not really four-part writing at all; it is a bass note plus a block of colour. Trying to analyse it as chorale texture leads nowhere. Once you want real voice leading in the left hand, you need free bass, where each button is a single note and every decision returns to you.

On the double bass you are one voice in someone else's texture, and voice leading is what makes a bass line good. A line that walks by step through a progression, using the nearest available chord tone, joins the harmony together. A line that leaps to the root of every chord chops it into blocks. Open strings matter here: an open E or A rings longer and louder than a stopped note, which is an asset in a sustained line and a liability if it sticks out in a quiet passage.

How to hear it and how to practise it

Start with two chords and four voices, written out, and play them slowly enough to hear each part separately. Then sing the tenor line alone while playing the rest. Singing an inner voice is uncomfortable and almost unreasonably useful, because it forces you to hear the part rather than the chord.

Next, take a standard progression such as one, six, four, five, one and write it three times with different soprano lines. The chords are the same; the pieces are not. Comparing them is the quickest way to feel how much of the musical effect lives in the top voice.

Finally, look at real music. Bach chorales remain the standard reference because they are short, dense and almost perfectly worked. Students at A&G Academy usually meet them around Grade 5, and the ones who play through a handful at the keyboard progress noticeably faster than the ones who only analyse them on paper.

Frequently asked

What is voice leading?

It is how each individual note in a chord moves to a note in the next chord. Good voice leading keeps shared notes in place, moves the rest by the smallest step available, and lets tendency notes such as the leading note resolve as the ear expects. It turns a chord sequence into a piece of music.

Why are parallel fifths avoided?

Because two voices moving in parallel fifths stop sounding like two voices. The interval is so blended that the ear fuses the parts, which defeats the point of independent lines. The rule belongs to common-practice four-part writing; plenty of styles, from medieval organum to rock guitar, use parallel fifths deliberately.

Can you control voice leading with a Stradella bass?

Not really. Each Stradella chord button sounds a preset voicing you cannot alter, so you cannot choose the top note, retain a common tone or avoid parallels. It works well as bass plus harmonic colour. For genuine independent part-writing in the left hand you need a free-bass or converter instrument.


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