Welcome! Here we'll cover the basics of Voice Leading and Counterpoint. The AP Music Theory Exam has a couple questions where we'll need to write four part harmony.
Part Writing Procedures
In order to achieve a level of independence of line for all four parts, parallel motion of Perfect Octaves, Perfect Fifths, and Unisons should be avoided. Since these are the lowest intervals on the overtone series, when two or more voices move in parallel motion in these intervals, they can blur together and sound like only one voice (in the case of unisons, they actually become one voice). Parallel motion by thirds, fourths and sixths is acceptable and often desirable, however, two voices should not move in parallel motion for several beats in succession. This would reduce their independence. To most easily avoid part writing errors, the following procedure is very helpful:
When problems arise:
When writing triads, there are only three pitch classes but four voices. This means that two or more voices will have the same pitch class. This is called doubling. When you have a choice, try to double the root or fifth of the chord. Avoid doubling any note with an accidental added or a tendency tone.
If you follow these basic steps, most part writing errors may be avoided. As rigid as they may seem, you often will have several choices yet available. The following example demonstrates these principles:
We begin the study of harmony with a four-voiced texture called chorale style. Two goals define this style: independence of voices and definition of tonality.
To create music in chorale style, we must control both the horizontal and vertical dimensions of the texture. Voice leading controls the relationship between voices. Rules of thumb concerning doubling and chord voicing shape the vertical disposition of the voices. A variant of chorale style called keyboard style alters both voice-leading and voicing rules to make practical performance by two hands at a keyboard.
THE FOUR VOICES
The study of harmony usually begins with a study of chorale style. Although strictly limited in scope, chorale style does provide basic training in the principles that govern a polyphonic (that is, many voiced) texture. Those principles, along with the techniques associated with them, are called voice leading.
Disposition of the Four Voices
Each part of a four-part texture is called a voice. The name and ranges of these voices are derived from the four standardized singing ranges: soprano, alto, tenor, and bass. You notate the four voices on a grand staff.
Ex. 5-1--Four Voices in Chorale Style (Bach, Chorale, 293)
We place the soprano and alto on the treble staff with the soprano on top. All soprano stems ascend. All alto stems descend. This makes the two voices visually distinct. We place the tenor and bass on the bass staff. All tenor stems ascend, and all bass stems descend.
Range of the Four Voices
With the exception noted below (see "Keyboard Style"), the four voices operate within restricted ranges, as shown in example 5-2.
Ex. 5-2--Ranges of the Four Voices
In chorale style, all four voices move in rhythmic unison, that is, each voice moves at the same time as every other voice. A succession of four-voice chords results.
We use scale-degree triads to form the chords that result from the movement of the four voices.
The bulk of a four-part texture consists of complete triads. Given a consonant, root-position triad, however, you may omit the fifth if this results in smoother voice leading. You may not omit the third.
Appendix L discusses the so-called horn fifths, which are a common exception to this last rule and are found in instrumental music of the eighteenth and nineteenth centuries.
The distance between adjacent voices may not exceed an octave, except between tenor and bass.
Disposing the voices evenly across the staff creates a chord in open position.
Disposing the voices so that the upper three are as close together as possible creates a chord in closed position.
Given the three pitch classes of a triad distributed among four voices, we must give one pitch class to two different voices. When two voices have the same pitch class we say that they are doubling each other (see example 5-1).
The primary rule for doubling is simple: Double the most stable notes of the triad. We apply this rule by considering the following alternatives in order:
Example 5-1, above, illustrates these principles of doubling.
For performance on a keyboard instrument, we can use a variant of chorale style called keyboard style. In keyboard style, the upper three voices remain in closed position. At the same time, we notate all three (soprano, alto, and tenor) on the treble staff. As a result, a musician can perform all three upper voices with the right hand, leaving the bass to the left. The extreme closed position of the upper three voices--a position caused by the size of the hand--often places the tenor voice higher than we would normally find in chorale style.
Ex. 5-3--Example 5-1 in Keyboard Style
To create a four-voice texture in chorale or keyboard style, you must learn how to control each voice, as well as the relationship between the voices. The principles and techniques involved in this control are referred to as voice leading. From the student's point of view, voice leading has two main goals: to establish and maintain the indpendence of the voices, and to establish and maintain a clear sense of tonality.
The soprano and bass, or outer voices, define the chorale texture. The inner voices (alto and tenor), serve a supporting role. We must control the relation between the outer voices (see "Simultaneous Motion," below) precisely. Soprano and bass must not only be strong in themselves, but the relationship between them must be strong as well.
Each voice forms a melody. The melodies in the outer voices are prominent, those of the inner voices supportive. These melodies move primarily by step, or conjunct motion. They move only occasionally by skip, or disjunct motion.
When an individual voice moves by seconds, it moves conjunctly. The seconds may be consonant or dissonant.
Ex. 5-4--Conjunct Motion
When an individual voice moves by an interval greater than a second, it moves disjunctly or by skip. (Some theorists call a skip a "leap." For our purposes, "skip" and "leap" are the same.)
Ex. 5-5--Successive Skips
Ex. 5-6--Disjunct Motion
We can distinguish among four possible relationships between a pair of voices. Voice leading considerations grade these from weak to strong as follows: parallel motion, similar motion, oblique motion, and contrary motion.
When two voices move in the same direction by the same interval, they move in parallel motion. Parallel motion is the weakest relative motion.
Ex. 5-7--Parallel Motion
You should avoid parallel motion between outer voices. Voices that move in parallel lose a degree of independence. Parallel motion between inner voices or between an inner voice and an outer voice is fine, providing the parallel interval is not from the list of forbidden parallels.
Parallel motion in perfect unisons, octaves or fifths between any two voices is forbidden (see "Forbidden Parallels," below).
When two voices move in the same direction but not by the same interval, they move in similar motion. Similar motion is slightly stronger than parallel motion.
Ex. 5-8--Similar Motion
Avoid similar motion between outer voices when moving into a perfect consonance (see "Hidden Parallels," below). Similar motion between inner voices or between an outer voice and an inner voice is fine.
When one voice moves while the other stays on the same note, oblique motion results.
Ex. 5-9--Oblique Motion
Oblique motion has the advantage of emphasizing the independence of the voices involved. For this reason, oblique motion is relatively strong. The moving voice, however, takes precedence over the stationary one. Thus, to emphasize both the independence and the equality of each voice, we look to contrary motion.
When two voices move in opposite directions, contrary motion results.
Ex. 5-10--Contrary Motion
Contrary motion is the strongest type of motion, since the two voices remain both equal and separate. Motion between outer voices should be primarily contrary.
FORBIDDEN PARALLEL MOTIONS
When voices move in parallel, one voice seems to track the other. The two sound less like equal voices than one voice imitated or doubled by another. When the interval that separates the two voices is a perfect consonance, the parallel voices fuse, losing any remaining sense of independence. Thus, tradition forbids the use of the three stronger perfect consonances--the unison, the fifth, and the octave--in parallel motion.
In the Bach Chorales, parallel perfect fourths appear in the upper three voices with regularity and in every conceivable configuration. Despite this, some theory texts (for example, Piston's Harmony), allow parallel fourths only when parallel thirds occur beneath them. Bach breaks this "rule" as often as he keeps it.
Ex. 5-11--Forbidden Parallel Unisons
Parallel motion by the unison destroys all independence of voices. When moving in parallel by the unison, two voices merge into a single series of pitches.
Ex. 5-12--Forbidden Parallel Octaves
· Forbidden Parallel Perfect Fifths. Like octaves, fifths in parallel convey the sense of a single voice doubled, and therefore parallel perfect fifths should be completely avoided (see example 5-13a). Two voices may move in parallel from a perfect fifth to a diminished fifth if the notes of the diminished fifth resolve (see example 5-13b). Remember: Diminished intervals resolve inward.
Ex. 5-13--Forbidden Parallel Fifths
These rules apply to two voices moving in parallel motion. Given two consecutive chords of a four-voice texture, each will usually contain a perfect octave and fifth. This is not a problem unless the repeated interval occurs between the same two voices and the voices move in parallel.
Ex. 5-14--Permitted Successive Fifths
Successive fifths that result from repeated notes pose no problem. In example 5-14a, the first fifth is between alto and bass, the second between alto and soprano. These fifths are not parallel fifths because they are not between the same two voices. Therefore, they are permitted. In example 5-14b, the first and second fifth are between the same two voices (alto and bass) but they do not move. This is not parallel motion but repetition. These repeated fifths are permitted.
Ex. 5-15--Hidden Parallel Ocaves
Voice Crossing and Overlap
Parallel motion is not the only challenge to the independence of voices. Registral confusion can lead to an equally serious loss of independence.
Ex. 5-16--Voice Crossings
Ex. 5-17--Voice Overlaps
General Guidelines for Composing Inner Voices
In realizing--that is, fleshing out--a four-voice texture, you should concern yourselves primarily with the outer voices. If you create strong voice leading between soprano and bass, you will run into few problems realizing the inner voices.
Whether to place a chord in open or closed position is a question of voicing. As a rule, you should keep the inner voices high. This leads both to a clearer sound and more easily realized part writing. Leave your voices room to maneuver, however. Continuous closed voicings force frequent voice overlaps and crossings. So, you are best off mixing closed with open voicings, favoring--all things being equal--the voicing that puts the inner voices higher. (In keyboard style, however, closed positions dominates, since overlaps are unprolematic.)
Broad rules regulate the composition of individual upper voices. (As we will see in the next chapter, the bass is a special case.) Govern your specific decisions by the following rules of thumb:Rule: When possible, repeat a note from one harmony to the next. If repetition is impossible, move by step. If you can neither repeat a note nor move by step, only then should you move by skip.
Rule: If you must skip, skip by the smallest (consonant) interval possible.
Only when the above options fail should you consider a large or dissonant skip. If you follow these guidelines in the order given, you will find that skips are seldom necessary and that note repetition and conjunct motion are the norm within the upper voices.
In creating music in chorale style, use complete triads. (If you omit any triad note, it should be the fifth.) Double (or--if omitting the fifth--triple) the root of the triad. Double the fifth only for some compelling voice leading reason. Avoid doubling the third of a triad except in very special contexts (described in Chapter 7). Do not double the leading tone (7^) in a V or vii.
Avoid parallel perfect unisons, fifths, and octaves completely. You may use parallel perfect fourths as long as they do not involve the bass. (If you are working from Piston's Harmony, however, parallel fourths must always be accompanied by parallel thirds in a lower voice.) Avoid voice crossings and voice overlaps. When possible, move by step.
Concern yourself primarily with the outer voices--the soprano and the bass. Maintain the independence of each and keep the relationship between them strong.
Principles of Part Writing
Traditionally, in the study of music theory, the principles of part wirting have been presented in four part chorale style. In this structure, the parts are referred to in the familiar terms of soprano, alto, tenor, and bass (SATB). The principles learned, however, are easily translated to virtually every medium of composition.
Because so much attention has been paid to four part textures, a widely accepted terminoly has been developed. Two typical structures are:
Close Structure: an octave or less between the soprano and tenor
Open Structure: more than an octave between the soprano and tenor
When writing in chorale style, various guidelines are necessary for smooth and strong voiceleading within the parts
1. Nothing should be written above the soprano or below the bass
2. The alto and tenor parts can cross, but only briefly and only for reasons of strong voiceleading
3. Avoid more than an octave between adjacent upper voices
a. No more than an octave between the soprano and alto
b. No more than an octave beween the alto and tenor
c. MORE than an octave between the tenor and bass is acceptable
4. Avoid parallel 5ths and 8ves
5. Avoid direct 5ths and 8ves
Often it is necessary to double or omit certain chord members to maintain strong voiceleading. When doing so, a few guidelines should be considered.
Try to double the root or third (double the fifth only if strong voice leading prohibits doubling the root or thirds
Do not double active (tendency) tones
Omit the 5th if necessary
o Omitting the root changes the chord entirely
o Omitting the third removes the quality of the chord (major or minor, etc)
Non Chord Tones Examples