The idea
In almost all tonal music, from the chorale to the pop song, the ear follows mainly two lines: the melody (the highest voice) and the bass. Their relationship, called outer-voice counterpoint, is the "skeleton" of the piece: if melody and bass work as good two-voice counterpoint, the inner voices are easily added; if they don't work, no voicing will save the progression. This is the heart of the approach of Aldwell & Schachter (Harmony and Voice Leading) and of tonal harmony and counterpoint courses.
The basic rules
- Consonances on strong beats: thirds/tenths, sixths, octaves, fifths (fifths and octaves sparingly, especially at arrival points).
- Contrary motion as the main choice; parallel tenths (compound thirds) as a safe choice for stretches in similar motion.
- No parallel fifths and octaves, nor hidden ones when the soprano leaps.
- Tendencies: the leading tone of the melody rises to the tonic; the seventh of a chord (often in the bass in 4/2 inversions) falls.
- Cadences: melody 2̂–1̂ or 7̂–1̂ over bass 5̂–1̂ (perfect cadence); melody on 2̂ or 7̂ over bass 5̂ (half cadence).
Linear intervallic patterns
Forte & Gilbert describe the pairs of intervals that repeat between melody and bass in progressions. The most common, in C major:
| Pattern | Bass | Melody | Resulting harmony |
|---|---|---|---|
| 10–10 | C–D–E–F (rises by step) | E–F–G–A | parallel tenths: C – Dm – Em – F, or inverted chords, depending on the inner voices |
| 10–7 (descending fifths) | C–F–B–E–A–D–G–C | E–E–D–D–C–C–B–C | C – Fmaj7 – Bø – Em7 – Am – Dm7 – G – C: the progression by fifths with sevenths |
| 5–6 (ascending) | C–C–D–D–E–E | G–A–A–B–B–C | C – Am/C – Dm – Bdim/D – Em – C/E: the ascending 5–6 sequence, basis of the Monte |
| 8–10 | C–A–F–D (descends by thirds) | C–C… (or stepwise melody forming octaves and tenths) | descending-thirds progressions |
| Voice exchange | E–D–C | C–D–E | I6 – V4/3 – I (or the reverse): the bass and the melody exchange the notes of the tonic chord, prolonging it |
(In the first row the choice of chords depends on the inner voices: the parallel tenths between the outer voices are the structural fact.)
Example phrase in C major (4 bars)
| Bar | Melody | Bass | Interval | Chord |
|---|---|---|---|---|
| 1 | E | C | 10 | I |
| 1 (second half) | D | B | 10 | V6 |
| 2 | C | A | 10 | vi |
| 2 (second half) | F | F | 8 (with contrary motion) | IV |
| 3 | E | G | 6 | I6/4 (cadential) |
| 3 (second half) | D | G | 5 | V |
| 4 | C | C | 8 | I |
First bars in descending parallel tenths (the model of the Romanesca / Pachelbel), then contrary motion toward the cadence.
Modern applications
- Topline and bassline in a pop track: check that the vocal melody and the bass (or the 808) don't always move in the same direction and that on the accented syllables they form thirds, sixths or octaves, not unintended seconds or sevenths (unless you want them).
- Bass riff and lead in EDM and funk: the same logic makes the groove "clearer."
- Writing for strings: violins I and cellos as the frame, then violas and second violins to fill in.
- Vocal arrangement: the highest and lowest voices of the choir decide the quality of the sound.
How to check it in the DAW
- Put melody and bass on just two tracks, mute everything else.
- Listen: do they sound like a small two-voice composition?
- Check the intervals on the strong beats (you can count them in the piano roll: 3–4 semitones or 15–16 = third/tenth, 8–9 = sixth, 12 or 24 = octave, 7 or 19 = fifth).
- Fix the points where melody and bass leap in the same direction to an octave or a fifth.
Related entries
Voice-leading rules, First-species counterpoint, Harmonizing a chorale step by step, Galant schemes, Harmonic sequences, Voice leading in pop, pads and synths, Schenkerian analysis step by step.