Definition
The first exercise of every harmony course is to connect two root-position triads in four voices (soprano, alto, tenor, bass) so that each voice moves in a singable and independent way. The rules that follow apply to the Classical chorale style and are the basis of all multi-part writing, from choral arranging to synth pads.
The three situations
How to connect depends on the distance between the roots.
1. Roots a fifth or a fourth apart (one common tone)
- Hold the common tone in the same voice.
- Move the other two upper voices by step to the nearest notes.
- Example in C, I–IV: C–E–G → C–F–A. The C stays, E rises to F, G rises to A.
2. Roots a third apart (two common tones)
- Hold both common tones; the third voice moves by step.
- Example I–vi: C–E–G → C–E–A. Only the G moves.
3. Roots a second apart (no common tones)
- The three upper voices move in contrary motion to the bass, to the nearest notes of the new chord.
- Example IV–V: the bass rises F → G; the upper voices fall: C → B, A → G, F → D.
Doublings and spacing
- In root position, preferably double the root.
- Never double the leading tone (B in C major).
- Maximum distance of an octave between soprano and alto and between alto and tenor; between tenor and bass it can reach a twelfth.
- The fifth can be omitted (tripling the root), never the third.
The rules of motion
- No parallel fifths or octaves (consecutive) between the same two voices.
- Avoid hidden fifths and octaves between the outer voices, unless the soprano moves by step.
- No crossing (the alto below the tenor) and no overlapping (a voice going beyond the note just left by the adjacent voice).
- The leading tone, in the outer voices, rises to the tonic.
- Avoid in any voice leaps of a seventh, augmented intervals, and the augmented second of the harmonic minor.
Complete example in C major: I–IV–V–I
| Voice | I | IV | V | I |
|---|---|---|---|---|
| Soprano | C | C | B | C |
| Alto | E | F | D | E |
| Tenor | G | A | G | G |
| Bass | C | F | G | C |
I–IV: common tone C held, the other voices rise by step. IV–V: no common tone, the upper voices fall while the bass rises. V–I: the leading tone B rises to C, the D rises to E, the G stays.
In minor
Between VI and V (in A minor: F major → E major) the voice that has the F must not rise to G#: it would be an augmented second. This is solved by doubling the third of the VI (the A) and moving the upper voices as follows: one A falls to G#, the other A rises to B, the C rises to E. The bass falls F → E; no upper voice has the F, so neither the augmented second nor parallel octaves with the bass arise.
Common mistakes
- Moving all the voices in the same direction as the bass: it is the most frequent cause of parallel fifths and octaves.
- Abandoning the common tone for no reason, making the voices leap.
- Doubling the third of the V (the leading tone).
- Leaving too much distance between alto and tenor.
How to use it in composition
- The same rules make pads and keyboard chords in pop flow smoothly: keep the common tones, move the rest only a little.
- In a choral arrangement, voices that move by step are easier to sing and to tune.
- The contrary-motion rule is the basis for avoiding the “block chord sound” on keyboards.
Exercise
- Connect in four voices in F major: I–vi–IV–V–I, following the three rules.
- Write the same progression in harmonic A minor and check the augmented second.
- Program the progression in the DAW first as root-position blocks and then with correct voice leading: compare the smoothness.
Connections
Voice-leading rules; SATB four-part writing; Root motion; Harmonizing a given bass; Voice leading in pop, pads, and synths.