hmmonyThe voice-leading rules hmmony checks
These are the conventions of four-part, chorale-style writing as most harmony courses teach them. Courses differ in the details — how strictly hidden fifths are treated, how far a voice may go outside its range — so where they differ, it says so. Errors are rules almost every course enforces; warnings are worth a second look.
Voice ranges
| Voice | Lowest | Highest |
|---|---|---|
| soprano | C4 | G5 |
| alto | G3 | D5 |
| tenor | C3 | G4 |
| bass | E2 | C4 |
C4 is middle C.
Parallel fifths Error
Two voices a perfect fifth apart move to another perfect fifth.
A perfect fifth is so consonant that two voices moving in perfect fifths sound like one voice thickened, not two independent lines. In four-part writing every voice is meant to be heard as its own melody, so consecutive fifths count as an error. This includes fifths an octave or more apart (a twelfth to a fifth, say) and fifths reached by contrary motion, which most courses also forbid.
Usually fixed by: Move one of the two voices to a different chord tone, or change the direction of one voice so the second interval is not a fifth. Often the easiest fix is in an inner voice: let the alto or tenor take the nearest other chord tone.
Parallel octaves and unisons Error
Two voices an octave (or unison) apart move to another octave or unison.
Two voices in octaves are heard as one voice doubled. The texture drops from four parts to three for that moment, and the doubled line stands out. The rule covers unisons, octaves and compound octaves, and octaves by contrary motion.
Usually fixed by: Check which note is doubled in the second chord. Usually one of the two voices should take a different chord tone — and if the doubled note is the leading tone or a chordal seventh, it should not be doubled at all.
Diminished fifth to perfect fifth Warning
A diminished fifth moves to a perfect fifth, with the bass involved.
Moving from a diminished fifth to a perfect fifth leaves the tritone unresolved and lands on an exposed perfect fifth. Between upper voices many courses allow it; with the bass involved most do not. A perfect fifth moving to a diminished fifth is generally fine.
Usually fixed by: Resolve the tritone: the lower note of a diminished fifth usually rises by step and the upper note falls by step, which gives a third rather than a fifth.
Voice range Error
A note is outside the usual range of its voice.
The exercise is written for singers. Each voice has a range it can sing comfortably: soprano C4–G5, alto G3–D5, tenor C3–G4, bass E2–C4. Some courses allow a step beyond these, so check what yours accepts — but a part that sits outside its range is no longer writing for that voice.
Usually fixed by: Move the note an octave into range if the line allows it, or rearrange the chord so this voice takes a different chord tone.
Spacing Error
More than an octave between soprano and alto, or between alto and tenor.
Wide gaps between the upper voices make the chord sound hollow and the voices sound separate. The bass and tenor may be further apart — a twelfth or more is common — because low intervals sound muddy when close.
Usually fixed by: Bring the upper voices closer: move the alto or tenor up, or the soprano down, to another tone of the same chord.
Voice crossing Error
A lower voice is above a higher voice in the same chord.
When the alto is above the soprano, say, the listener follows the highest note and loses track of which line is which. In chorale-style writing each voice keeps its position.
Usually fixed by: Swap the two notes between the voices, or choose different chord tones so the order is restored.
Voice overlap Warning
A voice moves past where the neighbouring voice just was.
If the tenor moves above the note the alto sang in the previous chord, the ear can connect the wrong notes into a line. It is less serious than crossing, which is why it is a warning.
Usually fixed by: Keep each voice between the previous notes of its neighbours — often by moving to a closer chord tone.
Leap larger than an octave Error
A voice leaps more than an octave.
Leaps of more than an octave are hard to sing accurately and break the line into two. Inner voices especially should move as little as possible.
Usually fixed by: Take the note in the other octave, or give the voice a different chord tone closer to its previous note.
Augmented melodic interval Warning
A voice moves by an augmented interval, such as an augmented second or fourth.
Augmented intervals are awkward to sing and sound foreign to the line. The augmented second between the sixth degree and the raised seventh in minor is the usual case: it appears whenever the harmonic-minor leading tone follows the sixth degree directly.
Usually fixed by: In minor, raise the sixth degree as well when it moves up to the leading tone, or approach the leading tone from another note. Otherwise choose a different chord tone.
Leap of a seventh Warning
A voice leaps a seventh.
Sevenths are dissonant leaps and hard to pitch. They are rare in chorale-style writing outside the bass, and even there they are better avoided.
Usually fixed by: Move in the other direction by a step or second instead — the same note in the other octave is usually much closer.
Doubled leading tone Error
Two voices sing the leading tone in the same chord.
The leading tone wants to rise to the tonic. If two voices have it, either both rise and make parallel octaves, or one goes elsewhere and the tendency is left unresolved.
Usually fixed by: Double a different chord tone — in a dominant chord, usually the root (the fifth degree of the key).
Leading tone in the soprano does not resolve Warning
The leading tone in the soprano does not move up a step to the tonic.
In an outer voice the leading tone is clearly heard, and the ear expects it to rise to the tonic. Inner voices may leave it — often the alto or tenor drops to the fifth of the tonic chord — but in the soprano it is expected to resolve.
Usually fixed by: Move the soprano up a semitone to the tonic. If the next chord does not contain the tonic, the leading tone is probably in the wrong voice for this progression.
What is not checked
hmmony does not identify chords, check that each chord is complete or correctly doubled (apart from the leading tone), realise figured bass, or judge the harmonic progression. Those depend on what the exercise asked for, and are for your teacher.