We use four-part writing (SATB), or part-writing, to aid in our study of harmony – specifically, the horizontal movement between harmonies. The four parts are Soprano (S), Alto (A), Tenor (T), and Bass (B). The range for each voice for part-writing purposes is smaller than what a trained vocalist could easily sing. Simplifying from the book, the ranges are:
- Soprano: G5 – C4
- Alto: C5 – G3
- Tenor: G4 – C3
- Bass: C4 – E2.
Chord voicing describes the way in which chord tones are distributed among the four voices, including the spacing between voices, and the doubling of chord tones if necessary. In practice, doublings and spacing will often be controlled by the motion between chords. For triads, at least one note will need to be doubled. The root and third of a triad must always be present.
This information is slightly different from the sheet. Below are the guidelines that I use for chord-tone doublings.
For root position major and minor triads:
- Usually double the root. It is the most prominent chord tone, and most consonant with the bass.
- The second choice is to double the chordal fifth. The P5 is the next most stable interval harmonically.
- Double the chordal third as a last choice. While OK, it does not provide the most stable sounding chord.
Major and minor triads in first inversion:
- Often double the chord tone in the soprano voice, down an octave in the tenor voice.
- Otherwise, double the root or chordal fifth.
- Never double the third of a V chord. This doubles the leading tone, which has such a strong tendency to resolve to tonic that it appear that you have parallel octaves even if you don’t move both leading tones to tonic.
- Always appear in first inversion to avoid having a diminished fifth above the bass.
- Always double the chordal third, which is the only note that doesn’t form a dissonant interval with another note.
The soprano, alto, and tenor parts (SAT) are considered the upper voices. Adjacent upper voices (soprano to alto, and alto to tenor) must remain within an octave of each other all the time. The spacing from soprano to tenor can be larger than an octave. There are no restrictions on the spacing from tenor to bass.
Open-spaced chords usually have more than an octave between the soprano and tenor. To achieve this spacing you will need to skip at least one chord tone between each upper voice. (Skipping one and only one chord tone of a triad between the upper voices will insure that you have a complete triad in the upper voices. Try it!)
Close-spaced chords have less than an octave between the soprano and tenor. To achieve close spacing you must not skip any chord tones between adjacent upper voices. (Even skipping one chord tone will result in an octave between soprano and tenor.)
Many first inversion triads are in what is called open-octave spacing, with the tenor doubling the soprano chord tone down an octave.