37.1 Introduction

In our discussion of rounded binary form (Chapter 36) we saw how music from the beginning of a composition may come back later on in the piece with new purpose. For many listeners, this can be a particularly enjoyable event, combining the satisfaction of recognition with the excitement of re-contextualizing familiar material. In this chapter, we will discuss several formal designs in which the return of the opening music is the foundational principle.

We will begin with ternary form, a three-part form where the opening section comes back more or less intact after a contrasting middle section. From there we will move on to rondo forms where the opening section is repeated two or more times, each after a different contrasting passage.

37.2 Ternary form

As you listen to the sonata movement below, keep the following questions in mind:

1. How would you characterize the opening melody?
2. Where does the opening melody end?
3. Does the opening melody return later in the piece?
4. If so, how would you characterize the intervening material?

In this piece, the opening section is 14 bars long and ends with a PAC in the home key of G major. A double barline at the end of m. 14 provides a visual cue that something is about to happen and the material that follows has a remarkably different character. Whereas the opening theme is serene and smooth, flowing from beginning to end without a single rest, the thematic material beginning in m. 15 seems stilted, is more forceful, and has sharper attacks. The change of key to E minor further emphasizes this contrast. When the opening material returns with the pickup to m. 35, the moment stands out, not just because of the reappearance of a familiar melody, but by virtue of the dramatically different material heard in between. The piece closes with a replaying of the entire opening section (compare mm. 1–14 with mm. 35–50), differing only in the final bars, where the music has been modified to provide a more conclusive ending. Just like the opening section, the closing section begins and ends conclusively in G major.

The following table summarizes the form of this movement:

This piece is in ternary form. Whereas the prefix “bi-” in “binary form” indicates that there are two distinct sections, the prefix “ter-” indicates that a ternary form has three distinct sections: || A || B || A⁽′⁾ ||. There are, however, several additional qualifications pertaining to the thematic and harmonic structure of such a piece.

The degree of contrast between the A sections and the B section heard between them is typical of a ternary form. Unlike binary forms—which have some moderately contrasting material but are usually more or less thematically unified—ternary forms tend to have dramatically different middle sections. The B section will often be set off from the A sections around it and will feature easily noticeable differences in rhythm, meter, tempo, articulation, and dynamics.

With regards to the harmonic structure of a ternary form, there are two important characteristics to keep in mind. First, the A section tends to be tonally closed. (Compare this with the opening section of a binary form which may be tonally closed but is more frequently tonally open.) When a ternary A section returns, its harmonic structure does not need to be adjusted to end the piece in the home key. The B section may be tonally closed or open. When the B section is tonally open, there may be a short transitional or bridging passage that connects back to the home key for the return of A. In Example 37–1, on the other hand, the B section ends with a strong E-minor PAC in m. 34, and the concluding A section starts immediately after.

Second, the key of the middle section is often selected for the sake of emphasizing the contrast described above. Ternary form B sections sometimes appear in the same closely-related keys typically found in binary forms: the dominant or relative. Often, however, they are set in some less predictable key. Historically speaking, ternary form developed later than binary form. Many composers—particularly those working in the nineteenth century and beyond—favored harmonically adventurous key areas and this preference is evident in many ternary forms from the era.

The following table lists some of the possible key areas of the middle section in a ternary form:

Overall, Example 37–1 passes through three keys: it begins with a tonally-closed A section in G major, moves to a contrasting B section in E minor (also tonally closed in terms of its own tonality), and concludes with the same A section heard at the beginning. You may have noticed, however, that these are not the only keys heard in this piece. Within each A section, we also hear a brief passage in D major. The following example shows the opening section with each of the five cadences labeled by type and key:

Both A sections begin with a four-bar period in G major: the antecedent ends with a HC on the third beat of m. 2 and the consequent ends with a PAC on the third beat of m. 4. After this, we find that all of the Cs have become C#s, suggesting a move to the dominant which is subsequently confirmed by an IAC in m. 10. This move to D major is fleeting: the opening period returns with the pickup to m. 11 and the A section ends in the home key of G major.

In a sense, the form of the A section resembles the form of the whole movement but on a smaller scale. The contrasting D-major material in mm. 5–10 is framed by tonally closed sections in G major, like a miniature ternary form! Given that the individual sections of a ternary form are often tonally closed and could work as standalone pieces, it is not uncommon for one or both of them to have a recognizable formal design of their own. As discussed in Chapter 36, form in tonal Western art music tends to be hierarchically structured.

Now consider the following example, another ternary form. This piece features much more adventurous chromaticism than the movement heard in Example 37–1, even in the A sections. Still, the ternary form is immediately apparent.

The opening A section is sixteen measures long and, despite the abundant accidentals, we may hear it in F# minor. Furthermore, we may hear these sixteen bars as forming a period with progressions resembling a plagal cadence in mm. 7–8 and an authentic cadence in mm. 15–16, once the persistent F#s in the bass give way to [latex]\hat3[/latex]– [latex]\hat4[/latex]– [latex]\hat5[/latex]– [latex]\hat1[/latex].

The B section is in the contrasting key of the submediant (D major). Like the F#s in the bass in the A section, the sustained Ds in the B section reinforce the tonality, even in the face of more adventurous chromaticism. Despite lacking even a single traditional cadence, we may hear the B section as being divided into four phrases, each consisting of a series of chords followed by a pair of sweeping arpeggios. The first phrase ends with an arpeggiated ii4/2 and the second with a tonic triad, again suggesting a kind of period. This period repeats with more fully-voiced chords in mm. 33–48.

The opening figures from the A section reappear in m. 49, but here they are transposed to D with several small alterations. This is not the beginning of the second A section. Rather, it is a bridge section that reintroduces elements from the beginning, setting up the true return of A in m. 57 following an arpeggiated augmented dominant in F# minor. The closing A section repeats the period heard at the beginning with some variation and ends in m. 72, after which a brief coda extends the final cadence.

Despite the many obvious differences, the overall form of this piece is remarkably similar to that of Example 37–1. Compare the following diagram with the one shown in Example 37–2:

Ternary forms are also extremely common in vocal music of the Baroque and Classical eras. Solo songs in operas, oratorios, and cantatas are frequently cast in this form. The following song is an example of a da capo aria, so named for the direction at the end of the notated music to go back and sing/play through the opening section one more time.

This aria begins with a twelve-bar piano introduction, ending with a HC in F major. The singer begins in m. 13 and continues until the authentic cadence in m. 42, after which the accompaniment plays a few bars alone to close the section. The contrasting B section begins in the key of the subdominant (Bb major ) in m. 45 and ends with a prolonged, tonicized C-major chord in mm. 63–67. This resolves to I in F major when the performers go back to the beginning and play through the introduction and A section one more time, ending at the “fine” in m. 44. In performing a da capo aria, it was customary to play the music as written the first time through. Then, partly to avoid monotony and partly to show off their virtuosity, the singer would add various embellishments to the repeated A section. The repeated beginning is therefore labeled A′ in the following diagram:

37.3 Compound ternary

Because the different sections of a ternary form are tonally closed, they may also be heard as standalone pieces. As such, they may themselves follow standard formal designs. (Recall our earlier discussion about how the A section of Example 37–1 resembled a miniature ternary form.) Keep this in mind as you listen to the minuet and trio below:

Taken by itself, the minuet in this piece (mm. 1–16) is a sectional rounded binary. There are two sections (mm. 1–8 and mm. 9–16), the second of which features a reappearance of the opening material. Similarly, the trio (mm. 17–34) is also a sectional rounded binary. It too has two sections (mm. 17–24 and mm. 25–34) with material from the first reappearing toward the end of the second. Both the minuet and the trio are tonally closed and could function on their own as standalone pieces. But heard together—and with the minuet replayed after the trio—the two combine to form a ternary structure: the minuet in Eb major serves as the opening and closing A sections and the trio in Ab major (the major subdominant) serves as the B section.

The following diagram summarizes:

When the A and B sections of a ternary form are themselves smaller binary forms, we refer to the overall structure as a compound ternary form. (Some texts and teachers use the term composite ternary form.) Compound ternary forms are ubiquitous in multi-movement works of the Classical era and beyond. Minuet and trio movements, such as the one shown above, are highly characteristic of symphonies, string quartets, and various types of solo sonatas.

37.4 Rondo forms

In a ternary form, we hear the A section return at the end, after a contrasting B section. Some pieces take this idea and expand it, repeating the opening material after each of a series of intervening sections. Consider the following example:

This example opens with a sixteen-bar double period in Bb major. (Note the double barline at the end of m. 16.) Over the course of the entire piece, this music comes back three more times: mm. 36–51, mm. 72–87, and mm. 107–122. When a composition returns to the opening material numerous times as it does here, it is said to be in rondo form. In this case, we hear four instances of the opening material with three sections in between. Since this rondo has seven distinct sections, we call it a seven-part rondo. The repeated material is called the refrain and the passages in between are called episodes.

The form of Example 37–10 is summarized in the following diagram with the refrain passages labeled A and the episodes labeled B and C:

Notice that the episodes in this piece are not nearly as harmonically contrasting as the B sections in the ternary forms discussed above. The first episode (labeled B in the diagram) begins in the home key and moves temporarily to the dominant (F major), but the piece abruptly returns to the tonic with the following refrain. The second episode (C) does not modulate and, in fact, does not contain any chromatic notes whatsoever. The piece is also more or less thematically unified, with none of the dramatic changes of character seen in a typical ternary form.

The harmonic and thematic consistency seen in Example 37–10 is typical, but some pieces do feature more harmonic and thematic variety. Consider the following example:

In this seven-part rondo, the last three sections are an exact repeat of the first three sections. Notice that aside from the occasional tonicization, the tonic stays consistent throughout this entire piece. Each of the episodes, however, moves to the parallel minor and, in doing so, exhibits more contrast than was seen in the previous example. (Note that the key changes in this piece are notated with accidentals instead of key signatures.)

The following rondo does not include a repeat of the B section:

In this rondo, the refrain is a continuous rounded binary in D major (mm. 1–20). Unlike the rondos discussed above, however, the refrain in Example 37–15 is heard just four times, the last of which is an embellished variation with the repeats written out (mm. 94–134). Correspondingly, there are just two episodes instead of three: a continuous rounded binary in the parallel minor (mm. 21–40) and another one in the subdominant key (mm. 61–80). The passage from mm. 81–93 is a bridge back to the tonic for the final refrain. Like a compound ternary form, the individual sections of this rondo are all binary forms and so we may think of this as a compound rondo.

This is also an example of a five-part rondo. Instead of the seven-part ABACABA form, five-part rondos usually follow an ABACA scheme. The following diagram summarizes the form of Example 37–15:

37.5 Summary

A ternary form has three sections and usually follows an ABA or ABA′ design. Unlike in binary form, where the first large-scale section is usually left tonally open, the A section of a typical ternary form is tonally closed. As such, the A section may be repeated at the end for a satisfying conclusion in the home key. Also unlike binary form, a typical ternary form is characterized by dramatic contrast.

With regards to harmonic structure, the contrasting middle section may be in one of the traditional secondary keys—the dominant or relative major—but will often be in a less closely-related key such as the submediant, subdominant, or parallel key. The B section may be tonally closed in its own key, but is often left open and may proceed to a bridge section that transitions back to the tonic. Thematically, the middle section tends to project a noticeably contrasting character in terms of rhythm, meter, dynamics, tempo, and articulation. The repeat of the A section at the end is sometimes written out, particularly if the composer chooses to add embellishments. In some cases, though, there may simply be a written direction in the score to go back to the beginning. Such is the case with a da capo aria, where embellishments in the repeated A section are left to the discretion of the performer.

The individual sections of a ternary piece may themselves follow a standard formal design. The A section, for example, may have its own contrasting middle section. Each individual section of a ternary form may be in binary form, too. If both the A section and B section are in binary form—as in a minuet and trio movement—the piece overall is said to be a compound ternary.

Pieces that feature more than one repetition of the opening section are said to be in rondo form. In a rondo, the repeated section is called the refrain and the intervening sections are called episodes. A seven-part rondo has four instances of the refrain and three episodes with the third episode typically being a repeat of the first: ABACABA. Other seven-part rondos follow an ABACADA design. A five-part rondo has just three instances of the refrain with two intervening episodes: ABACA. While the different sections of a rondo form each have their own distinct character, the contrast heard between the refrain and the episodes is typically much more subtle than the contrast heard between the sections of a ternary form.