As we want our part writing to sound stylistic for vocal music, the distances between our voices should help in this process. Here’s a summary of spacing guidelines.
- between S and A – 8ve or less.
- between A and T – 8ve or less.
- between T and B – no specific guideline. More space is possible. A 12th or less is a good rule of thumb.
Open and Close Spacing
Open – 8ve or more between S and T.
Close – Less than 8ve between S and T.
Notice that open and close spacing do not depend on the B. We are measuring the distances in the upper voices (SAT). Another way to describe open and close is whether or not you can fit another chord tone in between SA or AT. If you can: open. If you can’t: close (SAT each singing closest available pitch to each other).
We need to keep track of how each voice relates to each other so that we can make sure our voices are independent. There are five kinds of motion.
- Static – both voices stay on the same note. No motion.
- Oblique – one voice moves and the other stays the same.
- Contrary – both voices move in the opposite direction.
- Similar – both voices move in the same direction, but by different interval size.
- Parallel – both voices move in the same direction by the same interval size.
When we prioritize voice independence and smoothness, we prefer static (keeping common tones), contrary and oblique motion. Any time we write parallel motion, we need to make sure we are writing parallels that do not destroy voice independence. In fact, we find unstylistic parallels by checking motion this way.
Since we are writing three-note chords (and four-note chords where we sometimes leave out notes) with four voices, we have to write a note twice in a given chord. We call this doubling. To keep our music stylistic, we want to make sure we double stable notes in our chords. Here are the general guidelines.
- Root Position – Double the Root (in the Bass). This also goes for 7th chords when they are incomplete (omit fifth).
- Second Inversion – Double the Fifth (in the Bass)
- First Inversion – Double whatever is smoothest.
- Huge exception: Never double Ti! So don’t double the Bass in V6, and don’t write vii° and ii° in root position.
- Inverted 7th chords should be complete. No doubled note.