A Survey of Music Theory for the College Classroom: Diatonic Harmony

Root Position Part-Writing

Overview

Part-writing is a laboratory in which we can learn how individual voices move, how chords function, and how to write basic counterpoint. There are several considerations, including chord voicing, doubling of chord tones, voice leading, and harmonic progression. We will begin by writing SATB textures in root position only. The rules of root position writing will form the foundation for the more advanced, open-ended part-writing that we will study in the future.

Now that you know the basic principles of counterpoint, the next step is to add the alto and tenor lines to the soprano/bass textures you have created. Adding these inner voices should be the last step when writing in SATB texture, so always begin by producing good two-voice contrapuntal textures. The inner voices almost “write themselves” if the soprano/bass counterpoint has been competently written.

Voicing a Triad – Chord Spacing

The structure of a chord in SATB part-writing has an influence on the way it sounds. You should experiment with chord voicings at the piano keyboard to develop an awareness of the differences in sound.

  • Close Structure: the upper three voices are close together, with less than an octave between soprano and tenor
  • Open Structure: the upper three voices are more widely spaced, with an octave or more between soprano and tenor

open and close position

General Rules for Part-Writing

There are a few rules for part-writing to which you should adhere. Doing so will eliminate the possibility of a great many errors in your work.

  • Leading Tones – Leading tones in outer voices need to resolve up by a half step. Internal leading tones in the alto and tenor can leap down by a third to the fifth of the tonic chord. It is also possible to triple the root and omit the fifth by resolving the leading tone up to the tonic on the last chord of an example.

leading tone resolution 1

leading tone resolution 2

leading tone resolution 3

  • Sevenths – Sevenths are active tones and should be resolved down by step.

resolve sevenths down

  • Common Tones – Keep common tones when possible.

keep common tones

  • Leaps – In SATB textures, the upper 3 voices will generally move within a third with occasional leaps of a fourth within the phrase. At a new phrase, voices can move by more than a third. Bass leaps can form triads. All leaps in all voices that do not outline a triad should be followed by a step in the opposite direction. No leaps of a seventh are allowed.
  • Bass – The bass is the harmonic generator upon which everything is built. You can use leaps in the bass up to an octave within phrases and more than an octave between phrases.
  • Augmented Intervals – Avoid augmented 2nds (+2) and 4ths (+4). Diminished fifths (o5) can be used if the line immediately changes direction by step. In minor keys, don’t approach the leading tone (raised scale degree \(\hat{7}\)) from scale degree \(\hat{6}\) (natural or harmonic minor) because an +2 will result.

augmented intervals

  • Contrary Motion – Use contrary motion between soprano and bass whenever possible.
  • High Tenors – High tenors (A3 and above) are good if they do not interfere with the alto line.

General Rules for Doubling

Doubling refers to the practice of placing more than one voice on a given chord member. The guidelines are relatively simple and should be memorized.

  • Leading Tones and Sevenths – Do not double any altered chord tones, leading tones, or sevenths.
  • Root Position – In root position chords double the root. Occasionally doubling the third or more rarely the fifth is permitted. The final chord in a progression can feature a tripled root and a single third.
  • First Inversion – In first inversion, the following scale degrees are always good for doubling
    • Scale degrees \(\hat{1}\)\(\hat{2}\)\(\hat{4}\), and \(\hat{5}\) are important in the maintenance of tonality.
    • Scale degrees \(\hat{3}\) and \(\hat{6}\) are modal scale degrees, affecting the tonality of major and minor.
    • For first inversion triads, double scale degrees \(\hat{1}\)\(\hat{2}\)\(\hat{4}\), \(\hat{5}\), then \(\hat{6}\), then \(\hat{3}\), and never \(\hat{7}\) (the leading tone).
  • Second inversion – In second inversion, double the bass which is also the fifth of the chord.
  • Subtonic – It is fine to double the root in a subtonic VII chord.
  • Doubling Exceptions – There are a few exceptions to these rules.
    • Deceptive resolution of V to vi – In major keys, it is acceptable to resolve an inner voice leading tone down to the tonic in a V – vi deceptive progression. In minor keys, it is necessary to double the third in the VI chord to avoid writing an +2. Our preference is to double the third in the vi chord in major keys as well.

deceptive progression in major

deceptive progression in minor

Common Part-Writing Errors

Many errors can be prevented by writing good soprano/bass counterpoint and by following the general rules of part-writing and doubling. There are several common errors that you should watch for in your work, especially during your first attempts at SATB writing.

  • Voice Crossing – No part should be allowed to cross above the soprano or below the bass. Bach would allow the alto and tenor lines to cross briefly. We will not allow this, however.

crossed voices

  • Spacing Errors – Keep adjacent upper parts (soprano, alto, and tenor) within an octave of one another. The bass may be an octave or more from the tenor, however. Keeping a high tenor usually prevents this problem from occurring in the upper voices.

spacing error

  • Parallel Fifths and Octaves – Do not write parallel fifths and parallel octaves. Parallel thirds, fourths, and sixths may be used. Parallel fifths and octaves occur when two parts that are a P5 or P8 apart move to new pitches that are separated by the same interval. This includes both simple and compound fifths and octaves.

parallel fifths and octaves

  • Consecutive Fifths and Octaves – Do not write consecutive P5s and P8s by contrary motion because the effect is like that of a parallel fifth or octave.

consecutive fifths

consecutive octaves

  • Direct Fifths and Octaves – Direct fifths or octaves – also called hidden fifth and octaves – occur when the soprano and bass voices move in the same direction into a P5 or P8. The soprano part must leap, as shown in the following examples.

direct fifth

direct octave

  • Unequal Fifths – Unequal fifths refer to a P5 followed by a °5 or a °5 followed by a P5. These intervals are fine unless they involve a °5 – P5 between the bass and any upper voice.

 

unequal fifths

Examples of Root Position Part-Writing

The following examples are constructed on the bass and melody lines encountered earlier. Here is the melody that was added to the existing bass line in the Texture, Voice Leading, and Counterpoint chapter.

root position part writing example 1

After completing the soprano melody, the next step is to fill in the alto and tenor lines. The goal is to have smooth lines that fill in the harmonies, so keep in mind the general rules for part-writing and doubling listed earlier. Note the doubled third in the submediant chord in the V - vi progression. Also notice that the tenor begins on a relatively high note. Beginning with a high tenor allows it more freedom to move, keeps it out of the way of the bass line, and helps to eliminate spacing errors between the tenor and the alto voices.

Observe that in this example the inner voice leading tone in the tenor is resolved down by leap to the fifth in the final chord. While such a low tenor might be problematic earlier in the example, it is not a problem at a cadence or on the final chord.

root position part writing 2

The following is the bass line that was added to the existing melody at the end of the Texture, Voice Leading, and Counterpoint chapter.

root position part writing 3

Compare the resolution of the inner voice leading tone in the tenor on the last two beats to the previous example. The decision here was to triple the root on the ultimate chord rather than move the tenor down to the fifth of the tonic chord.

root position part writing 4

In both examples, common tones were kept whenever possible. Keeping common tones helps to ensure smooth writing as well as the elimination of errors in voice leading.

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