When we listen to rock songs, blues songs, pop songs, or country songs, there's a certain structure that we expect to hear. Usually there's a verse or two, and then a chorus, and then another verse or two, and then the chorus is repeated, and so on. This is a typical "form" (or structure) that rock and blues and pop and country songs tend to follow, and different songs use variations on this basic form.
In a similar way, classical music composers have a number of well-accepted forms which they can use when composing a piece. These forms have evolved over the generations through the experiences of composers around the world, because it's difficult to write new classical music pieces entirely from scratch without any structure or framework.
If we know the general outline of the various forms that a composer might use (sonata form, rondo form, etc.), this can help us keep track of where we are in a piece and where the piece is heading.
Classical Music Forms
These are the main forms used by classical music composers:
(also called "binary form"):
the Baroque period
(approximately 1600 to 1750) tended to use this form. A piece in two-part form has two sections, the first of which is usually labeled A, and the other is labeled B. After section A is performed, in many cases it's immediately repeated. Then the B section is performed, which sounds different than A yet is related to A. So a piece in two-part form might be written and performed as A-A-B, or A-A-B-B, and so on.
An example of two-part form is "La Commére" by François Couperin. This piece uses the A-A-B-B pattern, and it's in two-part form because it has an A section and a B section (not because it has two instruments):
0:04 - The beginning of the A section.
0:47 - The A section is now repeated.
1:30 - The beginning of the B section.
2:30 - The B section is now repeated.
(also called "ternary form" or "song form"):
This is similar to two-part form but with a repeated A at the end, so it tends to be written and performed as A-B-A, or A-A-B-A, or A-A-B-B-A, and so on. This form has been in continual use from the mid-1700's up to today. The A section was originally a minuet (a graceful dance), and the B section (sometimes called the "trio") is usually entirely different from the A section. For example, B might be in a key which contrasts with A yet is related to A. Or B might have a contrasting character from A, such as when A has a formal or loud or forceful sound and B has more of a softer or flowing or melodious sound. For variety, sometimes the last section (the final A) is slightly different from the original A section. Beethoven began using a "scherzo" (a fast and light-hearted composition) instead of a minuet for the A section, and later composers often used a scherzo as well. Originally there was a closing of some kind to mark the transition from A to B and from B to A, but later composers began using various types of "bridge" material at the transition points to maintain a sense of continuity.
Here's an example of a minuet:
Here's an example of a scherzo:
An example of three-part form is "Folk Song (Album for the Young, Op. 68, No. 9)" by Robert Schumann. This piece uses the A-A-B-B-A-A pattern:
0:01 - The beginning of the A section.
0:20 - The A section is now repeated.
0:38 - The beginning of the B section.
0:48 - The B section is now repeated.
0:58 - The A section is now repeated with a slight variation.
1:16 - The previous A section is now repeated.
(also called "sonata-allegro form" or "first-movement form"):
This form uses an A-B-A pattern. The first A is called the "exposition" (which might be repeated), and the B is called the "development," and the final A is called the "recapitulation." In the exposition section, two or three themes are introduced (exposed). The first theme is in the same key that the piece itself is in, and it tends to be more of a dramatic theme. The second theme is in a different key, and it tends to be more relaxed and lyrical. If there's a third theme then it's usually in the same key as the second theme. The development section develops the themes in different and unexpected ways, combining or varying the themes, sometimes adding new material, in any key(s) that the composer chooses. Sonata form is said to be the only form that has a special section (the development section) in which composers can work freely with musical ideas which have previously been introduced, without any formal rules to follow. The recapitulation section is a return to the exposition, in the original key. Sometimes the exposition is repeated exactly, and sometimes it's shortened or varied.
An example of sonata form is the 1st movement of Beethoven's "Symphony No. 5":
0:27 - The first theme in the exposition section is the famous "da-da-da-DAAAH." This four-note theme is then repeated throughout the orchestra.
1:04 - Everything stops for a moment, then there's a quick chord and another pause.
1:06 - The horns play the second theme ("da-da-da-daaah-daaah-daaah"). The second theme is in a different key than the first theme, and this key is used for the remainder of the exposition. The music is now more lyrical-sounding.
1:44 - The second theme reaches its climax (which is the end of the first A section in the A-A-B-A pattern), then there's a pause, then the entire exposition is repeated (which is the second A section in the A-A-B-A pattern).
3:04 - There's a pause at the end of the second run-through of the exposition section.
3:06 - The development section begins (the B section in the A-A-B-A pattern), in which Beethoven develops the two themes by exploring them in new ways.
3:50 - The music gets quieter and quieter until it erupts at 4:09 and again at 4:17.
4:22 - The recapitulation (the final A section in the A-A-B-A pattern) begins as the entire orchestra plays the "da-da-da-DAAAH" theme, followed by the string section repeating the theme.
4:37 - Here there's a short "cadenza" (solo) in which the oboe plays quietly by itself.
5:11 - The second theme is announced (just like at 1:06 during the exposition), but here it's the bassoons playing the second theme instead of the horns. This is because in Beethoven's time the horns could only play in a single key, which in this piece was the key of the second theme at 1:06. The recapitulation section is in a different key than that, so Beethoven couldn't use the horns in the recapitulation. Modern horns can play in any key, so some conductors use horns for the second theme in the recapitulation, but other conductors (such as the one in this video) use bassoons as Beethoven did.
5:53 - It sounds like the music should stop here as it did at the end of the exposition, but instead it keeps going. This is the "coda" (tail end) of the movement which leads to the thunderous ending at 7:09. It seems like the audience should begin clapping after the ending, but they're completely silent. This is because we've only reached the end of the first movement, and after a short pause the second movement will begin. The audience won't clap until the end of the fourth movement because that's when the piece is actually over.
This form uses patterns such as A-B-A-C-A, or A-B-A-C-A-D-A, or A-B-A-C-A-B-A, and so on. The A theme is the main theme (sometimes called the "refrain"), and the B, C, D, etc., themes are called "digressions" or "episodes" or "couplets." There can be any number of digressions, and the digressions can be of any length, but their purpose is to provide some contrast and balance to the A theme. Each time the A theme returns, it might be an exact repeat of A or it might contain some variations to keep things interesting.
An example of rondo form is the 3rd movement of "Piano Concerto No. 22" by Mozart, which uses the A-B-A-C-A-B-A pattern:
0:02 - The piano plays the beginning of theme A, which is repeated by the entire orchestra at 0:12.
0:21 - The piano plays the remainder of theme A, and the orchestra plus the piano play around with theme A for awhile.
1:50 - The piano hits a chord which sounds "different," signaling the beginning of a shift to a new key. As the piano player runs up and down the keyboard, he's actually performing a chord progression which gradually brings him to the new key (listen to the low chords that his left hand plays).
2:28 - The piano plays theme B in the new key, and the orchestra plus the piano play around with theme B for awhile.
3:31 - The piano is back to theme A, in the original key.
4:20 - The piano stops, and the orchestra begins playing theme C without the piano. Theme C is much slower than themes A and B.
4:43 - The piano begins playing theme C along with the orchestra.
5:07 - The piano stops, and the orchestra plays the second part of theme C.
5:33 - The piano begins playing the second part of theme C along with the orchestra.
6:50 - The piano brings us back to theme A again.
7:13 - The flute imitates what the bassoons had just played, but the flute takes us to a different key. Then the piano player runs up and down the piano for awhile, and it sounds as if he's taking us to yet another key.
7:53 - The piano is back to theme B, but in the original key (i.e. in theme A's original key). This is then imitated by the orchestra, which suddenly reaches a crescendo (loud chords) at 8:36.
8:41 - Now the piano plays a cadenza (a solo piece). Originally, the solo artist would improvise a masterful cadenza on the spot, but eventually people began memorizing cadenzas instead.
9:40 - The piano quietly brings us back to theme A, and then the orchestra plus the piano play around with theme A until the piece ends at 11:06.
A fugue is a "polyphonic" piece, which means that there are several "voices" that we must try to follow. The first voice will play a melody, and at some point the second voice will begin playing the same melody (possibly in a higher or lower key), and at some point the third voice will begin playing the same melody (possibly in a higher or lower key), and so on. For example, when children sing "Row, Row, Row Your Boat" as a round (each person singing the same song but starting at different times), they're performing a fugue.
If each voice plays or sings the same melody (imitating the first voice but starting at different times) throughout the entire piece as in "Row, Row, Row Your Boat," this is referred to as a "canon." If the voices play or sing the same melody as a fugue in part of a piece (but not throughout the entire piece), this is referred to as a "fugato." If one of the voices goes up to a higher note when the main voice goes down to a lower note, and vice versa, this is referred to as "inversion" (because the melody is being inverted or turned upside down from the main voice). If one of the voices plays the melody at half the speed by doubling the time value of each note (i.e. a quarter note becomes a half note and a half note becomes a whole note), this is referred to as "augmentation." If one of the voices plays the melody at twice the speed by halving the time value of each note (i.e. a half note becomes a quarter note and a whole note becomes a half note), this is referred to as "diminution." If one of the voices plays the melody backwards, this is referred to as "cancrizans" or "retrograde." If one of the voices plays the melody backwards and upside down, this is referred to as "inverted cancrizans" or "inverted retrograde."
It takes a lot of skill and thought to come up with a melody which can sound good when it's played by interweaving three or more voices as a fugue, especially if inversion, augmentation, diminution, cancrizans, or inverted cancrizans are being used.
A fugue starts with voice 1 playing a short melody (also called a "subject" or "theme") so that we can focus on it, then voice 2 will begin playing the same short melody. When voice 2 comes in, voice 1 is now playing something different, called a "countermelody" (or "countersubject"). When voice 3 comes in playing the melody, then voice 2 will begin playing the countermelody, and voice 1 will play something else, and so on. After all of the voices have played the melody once, this marks the end of the exposition section (sometimes the exposition section is then repeated). Next comes a section which doesn't contain the melody, and this is called an "episode." Then we hear the melody again, followed by a different episode, followed by the melody again, and so on. Each time the melody reappears it might be shown in a different light, either by using inversion, augmentation, etc., or by shortening it or lengthening it, or by playing it more loudly or softly, or by combining it with other themes, and so on, which tests the composer's ingenuity. Near the end of the piece, sometimes the voices will play the melody one after the other in quick succession, which is called a "stretto." The "cadence" (the closing phrase of the piece) should re-state the melody.
Bach was a master at writing fugues. In this video of Bach's "Prelude and Fugue in C major," notice that even though each voice has its own individual things to say (which our ears can't always follow), somehow all four voices blend and harmonize well with each other. That's what makes a fugue so difficult to write and to play. When there are multiple voices in a piece, this is referred to as "polyphony." When there are multiple voices in a piece and they blend and harmonize well with each other, this is referred to as "counterpoint."
2:33 - The pianist pauses after playing the prelude.
2:37 - His left hand begins playing the fugue melody (voice #1).
2:40 - His right hand begins playing the fugue melody in a different key (voice #2).
2:44 - His left hand begins playing the fugue melody in a different key (voice #3).
2:48 - His right hand begins playing the fugue melody in a different key (voice #4).
2:50 - From this point on you can hear the fugue melody showing up at different places throughout the remainder of the piece.
Here's a modern fugue which is based on the theme from the "Dragnet" TV show:
A famous example of a fugato is in the 4th movement of Mozart's "Jupiter Symphony." The coda (finale) begins at 8:09, and here Mozart creates a fugato by interweaving an unprecedented 5 themes. For a detailed breakdown of this fugato to help you hear all 5 themes, see
Mozart 6 - The Final Fugue:
Haydn's "String Quartet in D minor, Op. 76, No. 2, 3rd movement" is a canon in which two violins play a minuet, followed a moment later by a viola and a cello playing the same tune:
These are pieces which don't have a rigid structure, allowing composers to let their imaginations run wild. Many (but not all) fantasias contain a solo in which the performer plays at dizzying speeds.
(also called "symphonic poems" or "program music"):
These are pieces which are intended to depict a non-musical subject. For example, a tone poem might illustrate a poem, or a story, or a painting, or an experience that the composer had, and so on. A tone poem or symphonic poem usually consists of a single movement. If it's a longer piece, it's often referred to as "program music."
The tone poem "Mere Image" by Mannheim Steamroller traces the passage of life from youth to old age:
A famous tone poem is
An Alpine Symphony, Op. 64
by Richard Strauss, in the video below. This depicts the experiences of a group of people climbing an Alpine mountain from just before dawn until the following night. Strauss' composition contains the section titles shown here in quotes. The analysis of this tone poem comes from the Wikipedia article (see the above link), but the timestamps are mine:
00:00 ("Night") - The piece starts with the mysterious sounds of night-time on the mountain as the group begins their climb.
02:26 - The piece begins to build up to the dramatic sunrise.
04:59 ("The Ascent") - The low notes in the strings represent a "marching theme" (suggesting the act of climbing the mountain), and then at 06:21 the horns play a theme that represents aspects of the climb which are more dangerous or rugged. These themes will return occasionally throughout the piece.
06:32 - We hear the distant sounds of a hunting party, which is performed by a band playing offstage to create the effect of distance.
07:08 ("Entry into the Forest") - The sound changes as the group enters the forest, representing the foliage overhead obscuring the sunlight.
08:49 - ("Wandering by the Brook") - The music softens as the group hikes alongside a brook.
09:08 - We hear various birdcalls.
13:14 - The music begins to speed up and build in energy as the group approaches a waterfall.
13:32 ("At the Waterfall") - The group reaches the waterfall, and in a moment we hear the water cascading down the falls.
14:30 ("On Flowering Meadows") - The music becomes gentler as the group crosses a flowery meadow. The lower notes (the cellos) quietly play the marching theme, and the short, quick notes played by various instruments represent the small colorful flowers dotting the meadow.
15:24 ("On the Alpine Pasture") - Now we hear birdcalls, the bleating of sheep, cowbells, and the suggestion of yodeling.
17:27 - The going starts getting rougher.
17:46 ("Through Thickets and Undergrowth on the Wrong Path") - The music describes the group pushing through the dense thickets, trying to find the right path to take.
19:09 ("On the Glacier")
20:20 ("Dangerous Moments") - The music now describes precarious and perilous moments on the group's journey.
21:40 ("On the Summit") - The group reaches the summit.
30:15 ("Mists Rise")
30:33 ("The Sun Gradually Becomes Obscured") - A storm is coming, gradually obscuring the sun.
33:33 ("Calm Before the Storm") - We hear some thunder, and the group is now in the calm before the storm.
35:51 - We hear the trill of a piccolo (representing lightning), followed a moment later by distant thunder.
36:06 - We hear another trill of thunder, louder this time, followed closely by louder thunder, then more lightning and thunder. The wind picks up, and we hear isolated raindrops (the short, quick notes).
36:35 ("Thunder and Tempest, Descent") - The storm hits with full force, and the drenched group quickly heads back down the mountain. The music retraces many of the ideas that we heard during the ascent, but in reverse order and at a quicker pace.
39:34 - The storm is subsiding, and the rain is slackening off.