A Survey of Music Theory for the College Classroom: Chromatic Harmony 1

Binary and Ternary Form


As discussed earlier in this text, form refers to the organization or overall plan of all the musical elements in a piece, including rhythm, melody, dynamics, harmony, texture, articulation, register, and timbre and how they work together. We also found that there are three basic techniques that create musical form, including repetition, contrast, and variation. We now continue our examination of form by considering binary and ternary, two of the most significant structures in music.

One-part Form

One-part forms are tonally closed – i.e., they begin and end in the tonic key – and are not divisible into smaller sections. All periods except for those with modulating consequents are one-part forms. Other musical units that do not satisfy the definition of period may nevertheless be one-part forms.

One-part forms may be divided into discrete phrases, but generally lack the contrasts of design typical of multi-part forms such as binary, ternary, rondo, and so forth. These forms lack conclusive cadences in the original key until the end and are absent any thematic restatements in the tonic key following contrasting phrases. A famous piece that is an excellent example of one-part form is J. S. Bach’s Prelude No. 1 in C from Well-tempered Clavier, Book I.

Binary Form

Binary form features a division into two main units of equal or unequal length, in which the second part will be longer than the first part. Binary forms usually contain similar material in each part, and so may be labeled as AA’ or AB. They often feature a “two-reprise” construction wherein each half is repeated, either by using a repeat sign or with the music written out again, and they close with an authentic cadence in the tonic key. Binary forms do not bring back complete phrases from Part 1 at any point within Part 2 in the tonic key, which is the primary difference between binary and rounded binary or incipient ternary forms. Binary forms may show some development of motives from Part 1 in Part 2.

Binary forms are classed as continuous or sectional. In a sectional binary form, Part 1 (A) ends with a tonic triad in the tonic key of the movement or piece, usually as part of an authentic cadence. In a continuous binary form, Part 1 (A) ends with anything other than the tonic I (i) chord in the tonic key of the piece. Examples of continuous endings for Part 1 include the half cadence in the tonic key as well as a perfect authentic cadence in a related key after a modulation has occurred. Indeed, modulations to the dominant are common in Part 1 in binary forms. Most binary forms exhibit this continuous or open tonal plan.

The following graph shows a typical binary form, but as with the other forms discussed in this chapter, various modifications and differences are common.

binary form chart

The Air from Handel’s Harmonious Blacksmith provides a clear example of binary form.

Handel excerpt

Rounded Binary Form

Rounded binary form is a hybrid structure that falls between binary and ternary forms. Some authors use the term “balanced binary” for this form, reserving the term “rounded binary” for what we will call “incipient ternary.” Rounded binary form features the return of the second phrase of Part 1 (the closing material of Part 1) in the tonic key at the end of Part 2. This return provides a satisfying ending and a “rounding off” of the form without upsetting the essential binary construction and without the stronger effect that a return of the first phrase of Part 1 would have. Most rounded binary forms feature an open (continuous) plan, with modulation to the dominant at the end of Part 1 (A), although closed (sectional) examples are sometimes encountered. Rounded binary forms close with an authentic cadence in the tonic key, and like binary form each half is often repeated in a two-reprise design.

The following graph illustrates a typical rounded binary form. Note the arrow indicating the return of the second phrase of Part 1 at the end of Part 2. A typical phrase label scheme for rounded binary is a b c b’.

rounded binary form chart

A fine example of a rounded binary form is the theme to the first movement of Mozart’s Piano Sonata K. 331Recall that we examined the first two phrases of this piece in chapter 8 because they include cadential six-four chords.

Mozart excerpt

Incipient Ternary Form

There is a grey area in the distinction between rounded binary and incipient ternary forms, and many musicians and authors prefer to see these structures as rounded binary. We will reserve the term incipient ternary for those instances in which the first phrase of Part 1 returns at the end of Part 2, which emphasizes the feeling of return to the beginning and therefore more closely approaches the principle of ternary construction. It should be noted that incipient ternary forms are not as common as are rounded binary forms, and it is more important to understand what is happening in the music rather than require absolute agreement on terminology.

The two halves of an incipient ternary will most probably be of the same length, making it like binary and rounded binary forms. As with binary and rounded binary forms, many incipient ternary forms feature an open (continuous) plan with modulation to the dominant during the second phrase of Part 1. The two phrases of Part 2 are occasionally independent phrases and thus will not form a period. Incipient ternary forms close with an authentic cadence in the tonic key. 

The following graph exemplifies incipient ternary form. Note the arrow indicating the return of the first phrase of Part 1 at the end of Part 2, giving a feeling of return to the beginning associated with ternary form. A typical phrase label scheme for incipient ternary is a b c a’.

incipient ternary form chart

A good example of an incipient ternary form is the theme to the third movement of Mozart’s Piano Sonata K. 284We examined measures 8-10 of this piece in the chapter on modulation because they include a sequential modulation. The two phrases of Part 2 do not form a period and should be considered independent phrases.

Mozart excerpt 2

Ternary Form (ABA)

Ternary form is the most important formal design in Western music and is the basis for larger scale forms such as sonata form and the rondo. Ternary form features a division into three main units of equal or unequal length, with the first and third parts being clearly related. The second or middle part generally features tonal, thematic, textural, or developmental contrast that sets it apart from the outer sections. ABA’ occurs when the restatement of A is modified from the original statement.

Ternary forms can be tonally closed (sectional), featuring an authentic cadence in the tonic key at the end of both Part 1 (A) and Part 3 (A or A’). Alternately, ternary forms can be open (continuous), with modulation to the dominant by the end of Part 1 (A). Parts 1 and 3 in a ternary form are usually of comparable length, and ternary forms close with an authentic cadence in the tonic key.

Part 2 (B) is ordinarily open in its tonal structure but is occasionally closed. Part 2 can be based on Part 1 (A), or it may involve new material. The main purpose of Part 2 is to provide contrast with the outer parts, which it does by using different melodic materials, textures, tonality, or some combination of these. Part 2 can be of similar length to the outer parts – a period or phrase group, for example – or it can be short, often consisting of a single independent phrase. More rarely, it can be longer than the outer parts.

The return of Part 1 is often not exact, but can be abbreviated, embellished, lengthened, or otherwise varied to create an A’.  The difference between ternary form and its hybrid cousins (rounded binary and incipient ternary) is the substantial return of all or most of Part 1 in ternary form.

Part 1 is very often repeated in ternary forms, and Parts 2 and 3 are also often repeated as a unit. This repetition scheme is called “two reprise” when both A and BA are repeated. These repeat signs have no bearing on the overall form of the piece.

Rounded binary and incipient ternary forms will approach and eventually become ternary form as the second section (or Part 2) loses its cohesion as a single unit and divides into two parts (Parts 2 and 3 or BA/BA’). This is emphasized through the strength of one or more of the following factors:

  • An increase in the length of literal return at Part 3 (A).
  • An increase in the contrasting qualities of Part 2 (B).
  • An increase in the expectation of return by using a retransition, grand pause, rests, or other similar devices at the end of Part 2 (B).
  • An increase in the divisiveness of the joint between Part 2 (B) and Part 3 (A) through full harmonic closure of Part 2.

This minimum number of phrases in a ternary form is usually five – with the two periods that form Parts 1 (A) and 3 (A or A’) flanking a single independent phrase that comprises Part 2 (B). Sometimes ternary forms can grow to seven and more phrases, with phrase groups, periods, three phrase periods, and double periods comprising one or more of the constituent parts.

The following graph shows a typical ternary form. Keep in mind this is one of many layouts possible for this most significant of forms.

ternary form chart

Tchaikovsky’s German Song is an example of a piece in sectional ternary form. Parts A, B, and A are all parallel periods in this piece.

Tchaikovsky excerpt

Links and Transitions

Small units such as phrases and periods are sometimes connected in some way to one another to keep rhythmic, harmonic, and melodic motion active following cadences. The most common way of connecting phrases is to use an anacrusis, as Haydn does in measure 14 of his String Quartet Op. 74, No. 3: II Largo Assai, as shown in the next example. The first violin plays a connecting flourish of sixteenth and thirty-second notes that propels the music into measure 15 and the new phrase. Such links between phrases and periods are usually quite short, sometimes only a beat or a few beats in duration, but at times can be extended to a measure or more.

example of link

Transitions and retransitions are sometimes used between larger sections in binary and ternary forms, as well as in larger forms. The two basic functions of transitions and retransitions are tonal/harmonic preparation and thematic preparation. Depending on the length of the piece, these transitions can be range from several measures in length to as little as a single chord. Transitions can occur in the place of a strong cadence at the end of a section and may consist of figuration or important motives. The result is what some musicians call “traveling music” that smoothly takes the ear from one section to another.

A very straightforward retransition is found in the third movement of Haydn’s Piano Sonata in D, No. 50, Hob XVI/37. This transition, which spans from measure 81-93, devolves into rapidly repeated dominant eighth notes which serve as the tonal preparation for the final repeat of the A section in this compound rondo form.

Haydn excerpt 3

Compound Ternary Form

Compound ternary (also called composite ternary) is created when each section of a ternary form further divides into a binary, rounded binary, incipient ternary, or ternary structure. This is an extremely flexible form and was common during the 18th and 19th centuries. Many arias, movements in piano sonatas, slow movements of symphonies, and minuets/scherzos are in compound ternary form. 

Compound ternary can include an exact repeat of Part 1 (Compound Ternary with Da Capo), and this layout is common in minuets and scherzos. The middle section is frequently called the “trio” and is often texturally lighter than are Parts 1 and 3. Trios usually feature modulation to a closely related key. Part 3 (A) is a literal repeat of Part I. Compound ternary forms are often found as the second or more commonly the third movement in a four-movement scheme. They usually feature decisive cadences that punctuate the three sections and are written without any transitions between sections. Occasionally first and second endings are used.

Shown next is the basic layout of compound ternary form. The optional Introduction, transitions, and optional codas/codettas are not marked. Each of the three parts (ABA) of compound ternary are usually tonally closed, with each part beginning and ending in the same key.

A                      B (trio)                         A

aba (or ab)      cdc (or cd, or c)           aba (or ab)

Tonic               Related key                 Tonic

Examples of compound ternary form for further study include the Minuet and Trio from Mozart’s Eine Kleine Nachtmusik, Franz Joseph Hadyn’s Piano Sonata in C, H ob. XVI/3 III: Menuetto and Trio, and Beethoven’s Minuet in G Major, WoO 10, presented as the next example. Both the Minuet and Trio are two-reprise incipient ternary forms.

Mozart excerpt 3

Mozart excerpt continued

Codas and Codettas

Codas and codettas reinforce the tonic key of a piece and have a strong cadential function. Codetta translates to “little tail” in Italian, whereas coda means “tail.” Codas are longer than codettas and are usually reserved for the end of a movement or piece, so the longer the movement or piece, the more likely a coda rather than codetta will be used. Codettas can be used to end larger sections within a piece, such as at the end of an exposition in sonata form. Codas and codettas are occasionally marked as such in the score, but most often are not.

Codas and codettas have significance beyond the simple reinforcement of a cadence, and codas can include references to earlier themes and will sometimes even feature further development of these themes. In compound ternary forms, codettas – if used – will more often be seen in Part I and Part III than in Part II, with the longest codettas occurring at the end of Part III.

An example of a codetta appears at the second ending in the final measures of Schumann’s Little Morning Wanderer, a piece from the Album for the Young, Op. 68. 

Schumann excerpt

A clear example of a coda is found at the end of the final movement Mozart’s Piano Sonata K. 331. This famous movement, entitled Rondo Alla Turca, combines elements of compound ternary and rondo forms and ends with a satisfying coda that begins in m. 96 at the second ending of the last refrain, as shown next.

Mozart ending of alla turca 1

Mozart ending of alla turca 2

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