Note: This was written during my first semester of music theory. Therefore, while the information written here is true, one does not have to follow all of these guidelines for good partwriting.
Voice leading is the process of connecting harmonic progressions. Voice leading connects musical lines, giving a sense of direction for the piece’s melody.
When learning how to voice lead, it is important that one take heed of the following guidelines: keep the rhythm as simple as possible, ensure that each note in the melody is a member of the chord so that its produced sound harmonizes with the other tones, follow a stepwise motion (more formally known as “conjunct”) with a single focal point (often the melody’s highest note), and follow the steps that tendency tones “tend” to resolve to. For example, scale degree 7 has a strong desire to resolve up to scale degree 1. When writing leaps, one should avoid augmented intervals, 7ths, and intervals larger than an octave.
Voicing is the practice of arranging the spacing of a chord. The first step one must take when learning to write in a four-part texture (Soprano, Alto, Tenor, Bass) is deciding whether to write in an open or closed structure. In closed structure, it is important that no more than an octave can be observed between the Soprano and the Tenor, while in open structure, there is an allowance for an octave or more between the Soprano and Tenor voices.
However, even when writing in open structure, it is important for a beginning part-writer to take note of two main conventions. First, it is important that voices do not cross unless there is a musical reason to do so. For example, in Tavener’s “The Lamb” written for SATB chorus, there is frequent crossover between the Soprano and Alto voices, causing dissonance. However, traditionally one would not want the Alto voice to cross above the Soprano; it is usually not desired for a voice part to go above or below the one before it. Second, when spacing, there should be no more than an octave separating the Soprano and Alto, and the Alto and the Tenor (therefore resulting in no more than two octaves between the Soprano and the Tenor).
When writing, voice pairs are able to move in four ways: upper voices may move contrary to the bass, in oblique motion, parallel motion, or similar. It is also possible for an interval to remain stagnant, which is referred to as static. It is often preferred to avoid parallel 5ths and octaves in part writing, as they undermine the importance of the individual parts (Kostka). Doing so results in an objectionable parallel, which is generally avoided in tonal music written prior to the twentieth century.
In root position part writing, it is important to observe the guidelines of four- and three-part textures. In four-part textures, all notes belonging to the triad are present, with the root note repeated (“doubled”). In three-part textures, it is important to include the root and the third of the triad. If one chooses not to utilize the fifth, then the root will be doubled; however, the third cannot be omitted. It is also important to note that in both textures, the leading tone (scale degree 7) is usually not doubled, because it has a strong tendency tone, giving it a desire to move to tonic.
When writing parts that are a 4th and 5th apart, the most frequently used method (the rule of thumb, as learned in lectures) is to hold the common tone between the chords in the same voice. For example, when moving from a C Major triad (spelled as C, E, and G) when the Alto voice is the G to a G Major chord (G, B, and D), the Alto voice will hold the common tone of G (the note that is present in both triads) while the other voices will move in the same direction as the bass by step.
Another method (the first variation) is to move the upper voices in the same direction, but contrary to the bass. It is important to note that if the leading tone is in an inner voice (Alto or Tenor), then it does not need to resolve to scale degree 1.
The third method (the second variation) is when one note holds the common tone while another moves by step, and the other moves by a fourth. Although this is normally an acceptable progression, one must be careful, as this can cause voice overlap.
When writing with roots that are a 3rd or 6th apart, there will be two common tones. For example, when moving from C Major (spelled C, E, G) to E minor (spelled E, G, B), there are two notes in common—E and G. In four-part textures, the two voices with the common tone will hold it, while the remaining moves by step. In three-part textures, it is important to include the 5th of the second triad so that it can be evident to listeners that the entire chord has changed, rather than having performed an inversion of the same chord.
When writing roots a 2nd or 7th apart, there will be no common tones. In both four- and three-part textures, the upper voices will always move contrary to the bass. It is rare that progressions of a second lead to a proper cadence; they usually indicate that a musical phrase is not yet complete. One might be familiar with the deceptive progression (V-VI), which gives off a questioning tone rather than the comfort of a resolution to tonic.
The chapter* concludes with a brief explanation of how to write music for transposing instruments. As a double bassist (in spite of my primary academic concentration being voice), I have often had to transpose music down an octave, or change the tuning of my strings to match that of a cello’s when playing cello suites. Therefore, this section was very useful for me and many other students who may need to learn how to transpose their own music in the future.
In order to convey unity in tonal music, one must follow a sequence. A tonal sequence will maintain the piece’s key, while intervals may change. A real sequence will transpose to a different key. An example of a real sequence can be found in Disney’s The Hunchback of Notre Dame’s “God Help the Outcasts” (Schwartz), in which the song’s original key of Bb Major raises Bb and Eb to B Natural and E Natural as the chorus concludes their part and Esmeralda begins singing a new verse in C Major.
However, it is important to note that imitations can mimic real sequences. In a real imitation, although one voice may transpose the melody, another might repeat the original pattern. Therefore, this cannot be considered a real sequence. In a modified sequence, repetitions of the pattern will be neither tonal nor real.
In harmonic progressions, the strongest progressions are those of 4ths and 5ths. An example chord progression would be:
I IV vii I
ii V I
In this progression written, I chose to begin and end with intervals of 4ths, to begin and end on tonic, and to include a couple minor chords to provide some color. When moving up a 5th or down a 4th, this is considered following a circle-of-fifths sequence. Below is an example of the progression, with the chords written in the key of G Major.
G C fm G
am D G
In the circle of fifths, one may observe that it can be known that C Major is the fourth chord in the progression, because when moving one position to the left on the circle, the key of C Major can be found. D Major is known to be the 5th due to its being one position to the right on the circle. The other chords can then be found using this process as a guideline.
*This information came from Stefan Kostka’s textbook Tonal Harmony, 5th edition.