# 2.2: Basic Two-Voice Interval Progressions

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# 12.1 Introduction

Consider the following excerpts and in each case take note of the interaction that occurs between the melodies of the individual parts:

Example 12–1 is taken from a sixteenth century vocal composition by Orlande de Lassus. It begins with a single voice. When the second voice joins, three bars later, it imitates the melody heard at the beginning. As the piece progresses, the two voices are heard winding around one another, trading ideas in a kind of musical conversation. The excerpt shown in Example 12–2 comes from a string quartet by Halina Krzyżanowska. It begins with the four instruments playing at the same time. In terms of rhythm and pitch, their parts move in and out of alignment as they cooperatively shape a pair of musical phrases. Although the excerpt shown Example 12–2 was written nearly three and a half centuries later and sounds remarkably different, we may observe that it follows the same guiding principle as the excerpt in Example 12–1. Like Lassus, Krzyżanowska weaves simultaneously sounding melodies together to form a complex but harmonious musical texture. This bringing together of multiple melodic voices is known as polyphony and for many musicians, composers, teachers, and scholars, it is the very foundation tonal Western art music.

It is important to note that melodies like those heard in the examples above are not combined haphazardly. In most polyphonic tonal music the composer takes great care to consider the various harmonic sonorities that occur as the melodies move forward together. These composers, then, strike a careful balance: on the one hand they want each individual melody to retain and project a sense of independence, on the other hand they want all of the melodies to blend together and create harmonic cohesion.

The purpose of this chapter is to familiarize you with the concept and handling of polyphony in tonal Western art music. Interval progressions—patterns of intervals played in succession—form the backbone of this particular style and a firm understanding of how they work will enhance your experience of the music you hear, perform, analyze, and create. This chapter will outline and describe a series of standard progressions. You may think of the list presented here as a basic catalog of polyphonic building blocks. We will begin our discussion of interval progressions by revisiting the concepts of consonance and dissonance. The remainder of the chapter will describe the different ways in which two voices might move in relation to one another and the various interval progressions that employ these types of motion. (In subsequent chapters you will be given an opportunity to expand these progressions by adding a third and fourth voice—see, for example, Chapter 14.)

# 12.2 Consonance and dissonance

For now, we will consider only consonant intervals: the perfect consonances (unison, perfect fifth, and perfect octave), and imperfect consonances (minor/major thirds and minor/major sixths).

We will not yet consider dissonant intervals (minor/major seconds, minor/major sevenths, augmented or diminished intervals) and so the following sonorities will for now be excluded:

Notice that one of the intervals in Example 12–6 is perfect. The perfect fourth (P4) is a special case. Although considered consonant by some definitions, it is traditionally treated as a dissonance in two-voice textures. When only two voices are present, they are not permitted to form a perfect fourth or any other dissonance.

Activity 12-1

Activity 12–1

To fully understand basic interval progressions, it is essential that you first have a firm understanding of the intervals themselves. In this activity, you will identify a series of intervals and specify whether they are consonant or dissonant.

### Question

Identify the following interval:

major second (M2)

### Follow-up question

Is this interval consonant or dissonant in two-voice textures?

dissonant

### Question

Identify the following interval:

perfect fifth (P5)

### Follow-up question

Is this interval consonant or dissonant in two-voice textures?

consonant

### Question

Identify the following interval:

minor seventh (m7)

### Follow-up question

Is this interval consonant or dissonant in two-voice textures?

dissonant

### Question

Identify the following interval:

perfect octave (P8)

### Follow-up question

Is this interval consonant or dissonant in two-voice textures?

consonant

### Question

Identify the following interval:

perfect fourth (P4)

### Follow-up question

Is this interval consonant or dissonant in two-voice textures?

dissonant

### Question

Identify the following interval:

major third (M3)

### Follow-up question

Is this interval consonant or dissonant in two-voice textures?

consonant

# 12.3 Parallel motion

When two voices move simultaneously in the same direction, while keeping the intervallic distance between them constant, we say they are moving in parallel motion. This type of motion is common in Western polyphony, though with some regulation since it tends to diminish the perceived independence of the voices. Parallel motion is typically used only with certain intervals. The following progressions, for example, are quite common:

Note that we are not concerned with the exact quality of these imperfect consonances. The intervallic motion shown in Example 12–7, for example, is considered parallel even though it moves from a major third to a minor third.

Both of the progressions shown above also commonly appear in reverse:

These examples show the same standard interval progressions as those discussed above, but now with descending motion in both voices. The interval progressions outlined in the remainder of this chapter are similarly reversible and from this point on, each progression will be presented alongside the reversed version.

Parallel thirds and parallel sixths are consonant but also allow the listener to identify the individual voices. They are therefore ubiquitous in tonal Western art music. Voices forming perfect intervals (unison, fifth, octave), on the other hand, blend together so well that many practitioners feel they suppress the listener’s sense of differentiation among voices.

When pairs of voices maintain perfect intervals as they move up or down, a listener may begin to lose the sense that they are actually hearing more than one pitch at a time. In other words, the individual melodic voices risk losing their independence. In this style of music, then, parallel motion is strictly avoided between two voices forming a perfect interval. The following interval progressions, then, are almost always avoided in this style:

Note: Many texts and teachers describe parallel unisons, fifths, and octaves as being “forbidden.” But although they are strictly avoided in this style of music, they are quite common in many other styles. Aesthetic preferences differ wildly from individual to individual, community to community, time to time, and from one part of the world to another. Keep in mind that this book is concerned primarily with tonal Western art music and these ideas are intended to enhance your understanding of that particular historical style. It is important to understand that differences between the music discussed here and other musical styles that may not follow the same conventions should not be interpreted as an indication of any one music’s superiority over another.

Although this chapter is concerned with consonant intervals only, it is here worth mentioning one interval progression that contains a dissonance. As mentioned above, parallel motion from one perfect fifth to another is not permissible in this style. Motion from a perfect fifth to a diminished fifth, on the other hand, is:

For reasons that will become clearer later on in Chapter 16, the interval progression shown in Example 12–17 is allowed in this style. Movement between these intervals in the opposite direction—where the perfect fifth arrives via stepwise motion in both voices—is considered forbidden and should be avoided in two-voice textures:

Note: As we will see in later chapters, the d5–P5 progression does appear in textures with more than two voices. (See, for example, Chapter 17.)

Activity 12-2

Activity 12–2

Certain types of parallel interval progressions are allowed in two-voice textures while others are considered forbidden when writing in this style. In this activity, you will be presented with various types of parallel interval progressions. It is up to you to determine which are permissible and which should be avoided.

### Question

Is the following parallel interval progression permissible or forbidden in this style?

Forbidden. Parallel fifths are not allowed in this style.

### Question

Is the following parallel interval progression permissible or forbidden in this style?

Permissible. Parallel thirds are allowed in this style.

### Question

Is the following parallel interval progression permissible or forbidden in this style?

Forbidden. Parallel octaves are not allowed in this style.

### Question

Is the following parallel interval progression permissible or forbidden in this style?

Permissible. Parallel thirds are allowed in this style, even with chromatic alterations.

### Question

Is the following parallel interval progression permissible or forbidden in this style?

Forbidden. Parallel fifths are not allowed in this style.

### Question

Is the following parallel interval progression permissible or forbidden in this style?

Permissible. Parallel sixths are allowed in this style.

# 12.4 Contrary motion

When one melodic voice ascends while another descends, we say that the two voices are moving in contrary motion:

Many composers of early polyphonic music showed a preference for this type of motion since it projects a sense of melodic independence. The two voices—though singing together—maintain their own identity, leading to a richer, more interesting texture.

Because of the acoustic properties described above, the group of standard progressions involving parallel motion is relatively small. By contrast, the group of interval progressions where voices move in contrary motion is much larger. It will be helpful, then, to divide this group into three categories:

• Both voices move by step
• One voice moves by step, the other by leap
• Both voices move by leap

## Both voices move by step

We will begin by looking at interval progressions where each voice moves by step in contrary motion. These progressions may start from a unison, a third or a sixth. In each case, the two voices begin with a consonant interval and move in opposite directions (contrary motion). A unison expands to a third, a third to a perfect fifth, and a sixth to an octave, as shown here.

Notice that there is no standard interval progression in which the voices expand outwards by step from a perfect fifth. If two voices forming a fifth were to move away from each other by step, the result would be a seventh, which is a dissonance and is not permitted here.

These interval progressions can also appear as compound intervals. In other words, the 1–3 interval progression shown in Example 12–19 (and reproduced in Example 12–25a) can also be written as an octave followed by a tenth. The interval progressions shown in Example 12–25a and Example 12–25b, in other words, are generally considered to be equivalent:

All of the interval progressions presented in this chapter are also valid in their compound forms. For the sake of clarity, however, interval progressions will here be listed only in their simple forms. Compound intervals will only be used for naming progressions when the intervals expand from smaller than an octave to greater than an octave or vice versa.

Activity 12-3

Activity 12–3

This activity will give you the opportunity to complete a short interval progression. For each exercise, provide a second interval so that both voices move by step in contrary motion. For example, the following minor third…

…could move in stepwise, contrary motion to either a perfect fifth…

…or a unison:

### Question

Continue the following interval progression with stepwise, contrary motion:

Hint

Remember, for this exercise both voices must move by step in opposite directions.

upper voice to G# and lower voice to B or upper voice B and lower voice to G#

### Question

Continue the following interval progression with stepwise, contrary motion:

Hint

Remember, for this exercise both voices must move by step in opposite directions. Also, the second interval must be consonant.

upper voice to Ab and lower voice to F

### Question

Continue the following interval progression with stepwise, contrary motion:

Hint

Remember, for this exercise both voices must move by step in opposite directions.

upper voice to F# and lower voice to B or both voices to D

### Question

Continue the following interval progression with stepwise, contrary motion:

Hint

Remember, for this exercise both voices must move by step in opposite directions. Also, the upper voice in the second interval should not cross below the lower voice.

upper voice to Eb and lower voice to C

## One voice moves by step, the other by leap:

The second category of contrary-motion interval progressions includes those in which one voice moves by step and the other by leap. One example is a perfect fifth expanding to a perfect octave:

In the first part of this example, the upper voice ascends by step from B to C while the lower voice leaps from E down to C. The same progression in reverse is, of course, also valid.

These roles could also be reversed. In the following example, the upper voice leaps, while the lower voice descends by step:

A third expands to a sixth in the same way, with a step in one voice and a leap in the other:

## Both voices move by leap:

Finally, there is the third category of contrary motion in which both voices move by leap. The only permitted progression in this category is the 6–10 (and 10–6) progression:

Notice that the while the soprano moves from B to D, the bass does just the opposite: D to B. This swapping of pitch classes is known as a voice exchange. Voice exchanges are a common technique in music of this style. In analysis, they are often highlighted by using a pair of crossed lines, as shown in Example 12–34.

Activity 12-4

Activity 12–4

There are usually several different possibilities for following a given interval in a basic interval progression. In this activity, you will become more familiar with this multiplicity of successions by completing an interval progression in four different ways.

### Question

Complete the following interval progression in four unique and valid ways by providing voices for the second beat moving in either parallel or contrary motion.

Possible answers: upper voice to B / lower voice to D; upper voice to G / lower voice to B; upper voice to G / lower voice to E; upper voice to F / lower voice to D; upper voice to B / lower voice to B; or upper voice to C / lower voice to A.

# 12.5 Similar motion

A second large category of interval progressions includes those where the two voices move in similar motion. In each of these progressions, one voice moves by step, the other by leap in the same direction. In the following example, we see the two voices forming a third expanding to a fifth, with both moving in the same direction.

Like the second category of contrary-motion progressions, the roles of the two voices may be reversed. In the previous example, the upper voice moved by step while the lower voice moved by leap. In the following example, it is the lower voice that moves by step and the upper by leap:

There are two other such similar-motion interval progressions, 5–6 (and its reverses):

and 6–8 (and its reverses):

There is one special type of similar-motion interval progression which in three- and four-voice settings, occurs mainly between the lowest voice—the bass—and one of the voices sounding above it. In this progression, the upper voice moves by step while the bass leaps by fifth in the same direction:

Activity 12-5

Activity 12–5

As you saw in the previous activity, there are often several possibilities for following an interval. In this activity, you will complete an interval progression in four different ways using similar motion.

### Question

Complete the following interval progression in four unique and valid ways by providing voices for the second beat moving using similar motion only.

Possible answers: upper voice to G / lower voice to G; upper voice to G / lower voice to B; upper voice to C / lower voice to E; upper voice to B / lower voice to G; or upper voice to E / lower voice to C.

# 12.6 Oblique motion

The last type of motion for interval progressions is oblique motion, where one voice remains stationary while the other moves against it by step (or leap). The 5–6 progression is typical:

Activity 12-6

Activity 12–6

Being able to recognize the various basic interval progressions will help you immeasurably in your study of tonal Western art music. In this activity, you will identify various basic interval progressions and classify them as exhibiting parallel, contrary, similar, or oblique motion.

### Question

Identify all of the intervals in the following two-voice progression:

### Follow-up question

Now label each pair of intervals as having parallel, contrary, similar, or oblique motion.

Activity 12-7

Activity 12–7

Basic interval progressions form the basis of tonal Western art music. In this activity, you will identify basic interval progressions in an excerpt from an actual composition. You may notice that not all of the voices seem to follow basic interval progressions exactly. This will be clarified in later chapters.

### Question

Identify the basic interval progression highlighted by the red notes:

The canto primo and canto secondo parts are moving in parallel thirds (3–3).

### Question

Identify the basic interval progression highlighted by the red notes:

The canto secondo and basso parts are moving in contrary motion from a sixth to an octave (6–8).

### Question

Identify the basic interval progression highlighted by the red notes:

The canto primo and canto secondo parts are moving in contrary motion from a third to a sixth (3–6).

### Question

Identify the basic interval progression highlighted by the red notes:

The canto secondo and basso parts are moving through parallel sixths (6–6).

### Question

Identify the basic interval progression highlighted by the red notes:

The canto primo and canto secondo parts move by oblique motion from a sixth to a fifth (6–5).

### Question

Identify the basic interval progression highlighted by the red notes: