To keep our part writing stylistic to the common-practice period, we have a bunch of things we should avoid. This is not a complete list of part writing errors.
Parallel 5ths and 8ves
When we write parallel P5s and P8s, two voices that were independent suddenly fuse to sound like one thing. We want to keep all of our voices independent.
- Parallel 5ths – In the same voice pair, a harmonic P5 is followed by another P5. (the melodic intervals do not affect this.) If either of these intervals is a °5, the music is acceptable.
- Parallel 8ves – In the same voice pair, a harmonic P8 is followed by another P8.
5ths and 8ves in Contrary Motion
Like the parallel examples above, these same harmonic intervals in contrary motion are unstylistic. You cannot fix a set of parallels 5ths by changing the octave of one note.
Direct 5th and 8ve
These issues have a similar sound, but are not set up by the same interval. A direct 5th or 8ve has three parts.
- A P5 or P8,
- between S and B only, and
- arrived at by similar motion.
If one of these parts is missing, it is not a direct 5th or 8ve. These issues are sneaky, so make sure you take note of any 5th or 8ve your write between the S and B.
Leading Tone Problems and Tendency Tones
The leading tone, Ti, is a tricky note. It is the main tendency tone in any major or minor key. That is, Ti needs to resolve so badly that if you are not careful, there are a bunch of issues that might happen.
There are three main tendency tones. These active tones sound unstable and when we hear them, we want them to move to a stable tone.
- Ti resolves to Do.
- Fa resolves to Mi or Me.
- Le resolves to Sol.
Doubling the Leading-Tone
As I mentioned on the Doubling page, we don’t want to double the leading-tone. Ti needs to resolve in both voices, and you are honor bound to resolve both of them up to Do creating parallel 8ves. If you need Ti in a chord, you only need one.
Not Resolving Leading-Tone in S or B
Since the S and B are on the top and bottom of the texture, we here them more clearly and not resolving Ti to Do is more obvious. So keep track of Ti and have it go to Do.
There is a general rule to not write melodic augmented intervals. Augmented intervals are hard to sing. Have you tried to sing harmonic minor recently? Both augmented intervals in diatonic major and minor involve Ti.
- Ti up to Fa and Fa down to Ti. This create an +4, and since both notes are tendency notes, you have to resolve the second tone out rather than follow normal melodic guidelines (leap followed by step in opposite direction).
- (The reverse is a °5 and the resolution follows what we expected for melodic leaps.)
- Le to Ti. This +2 is the one in harmonic minor, and good luck getting your local church choir tenors to sing it. This is easy to miss if you forget to add the accidental for Ti (making it look like a M2 instead). That becomes two problems instead of one. Le is another tendency tone and requires resolution to Sol, which moving to Ti makes a third problem.
More than 8ve between SA or AT
Either of our upper voice pairs, SA or AT, should only be an 8ve apart or less. We like the sound of the upper voices close together; it sounds good. When they get too far apart, there are large gaps in the texture that can make the music sound hollow. We can keep a rich choral sound by following spacing guidelines.
Voice Crossing and Voice Overlap
The opposite is a problem too. If any voice pair gets too close together, we lose track of which voice is which.
- Voice Crossing – when two adjacent voices switch places (A goes above S, T goes above A, etc.) This is very easy to do between the A and T, because they are one separate staves. So make sure you keep track of the relationship between A and T.
- Adjacent voices can sing the same note, but must leave the unison in opposite directions by oblique or contrary motion. (They can sing this unison for as long as you want = static motion.)
- Voice Overlap – when a voice goes above or below where another voice used to be in the previous chord. This is easy with the T and B, because the B leaps around so much and if the T is low in its range. This is often fixable by dropping the B an octave.