Writing Vocal Parts
Although chords are the main source of harmonies, a singer can only deliver one note at a time. This means that the notes of a chord must be shared between voices. In the case of a simple harmony based on 3rd intervals, it is possible to select just one chord tone for a harmony, but if more than one note is desired, the chord must be split and written on different staves. Here is the chord progression C F G C written on three staves. The top two are for Soprano (S) and Alto (A) voices and use a treble staff, while the bottom notes for a Baritone (B) voice are on the bass staff.
When writing harmonies, the harmonising voices can either follow every note of the melody, or sing single sustained chord tones (notes of the chord) while the melody moves between them. Sometimes one approach works best and sometimes the other. In the example that follows, the melody is in the Bass and the Soprano and Alto voices harmonize every note. In this situation, any notes from the scale of the key can be used. As long as you do not use notes from outside the key, the notes will harmonize. The first option would be to use two thirds one above the other – i.e., a soprano note one third interval above the alto note, which is a third interval above the melody.
