Canon (music)

Contrived example of a canon in three voices at the unison, two beats apart.  Play 

In music, a canon is a contrapuntal compositional technique that employs a melody with one or more imitations of the melody played after a given duration (e.g., quarter rest, one measure, etc.). The initial melody is called the leader (or dux), while the imitative melody, which is played in a different voice, is called the follower (or comes). The follower must imitate the leader, either as an exact replication of its rhythms and intervals or some transformation thereof (see "Types of canon", below). Repeating canons in which all voices are musically identical are called rounds – "Row, Row, Row Your Boat" and "Frère Jacques" being widely known examples. An example of a classical strict canon is the Minuet of Haydn's String Quartet in D Minor, Op. 76, No. 2 (White 1976, 66).

Accompanied canon is a canon accompanied by one or more additional independent parts which do not take part in imitating the melody.

History

During the Middle Ages, Renaissance, and Baroque—that is, through the early 18th century—any kind of imitative musical counterpoints were called fugues, with the strict imitation now known as canon qualified as fuga ligata, meaning "fettered fugue" (Bridge [1881], 76; Mann, Wilson, and Urquhart n.d.; Walker 2000, 1). Only in the 16th century did the word "canon" begin to be used to describe the musical form created by such a procedure (Mann, Wilson, and Urquhart n.d.). The word is derived from the Greek "κανών", Latinised as canon, which means "law" or "norm", and may be related to 8th century Byzantine hymns, or canons, like the Great Canon by St. Andrew of Crete. In contrapuntal usage, the word refers to the "rule" explaining the number of parts, places of entry, transposition, and so on, according to which one or more additional parts may be derived from a single written melodic line. This rule was usually given verbally, but could also be supplemented by special signs in the score, sometimes themselves called canoni (Bridge [1881], 76). The earliest known non-religious canons are English rounds, a form called rondellus starting in the 14th century Mann, Wilson, and Urquhart n.d.; the best known is Sumer Is Icumen In (composed around 1250), called a rota ("wheel") in the manuscript source (Sanders 2001a; Sanders 2001b).

Types of canon

The most rigid and ingenious forms of canon are not strictly concerned with pattern but also with content. Canons are classified by various traits: the number of voices, the interval at which each successive voice is transposed in relation to the preceding voice, whether voices are inverse, retrograde, or retrograde-inverse; the temporal distance between each voice, whether the intervals of the second voice are exactly those of the original or if they are adjusted to fit the diatonic scale, and the tempo of successive voices. However, canons may use more than one of the above methods.

How voices in a canon are named

Although, for clarity, this article uses leader and follower(s) to denote the leading voice in a canon and those that imitate it, musicological literature also uses the traditional Latin terms dux and comes for "leader" and "follower", respectively.

Number of voices

A canon of two voices may be called a canon in two, similarly a canon of x voices would be called a canon in x. This terminology may be used in combination with a similar terminology for the interval between each voice, different from the terminology in the following paragraph.

Another standard designation is "Canon: Two in One", which means two voices in one canon. "Canon: Four in Two" means four voices with two simultaneous canons. While "Canon: Six in Three" means six voices with three simultaneous canons, and so on.

Simple

A simple canon (also known as a round) imitates the leader perfectly at the octave or unison. Well-known canons of this type include the famous children's songs Row, Row, Row Your Boat and Frère Jacques.

Interval

Beginning of psalm motet De profundis by Josquin des Prez, featuring a canon at the fourth between the two upper voices in the first six bars.  Play 

If the follower imitates the precise interval quality of the leader, then it is called a strict canon; if the follower imitates the interval number (but not the quality—e.g., a major third may become a minor third), it is called a free canon (Kennedy 1994).

Contrapuntal derivations

The follower is by definition a contrapuntal derivation of the leader.

Canon by inversion

An inversion canon (also called an al rovescio canon) has the follower moving in contrary motion to the leader. Where the leader would go down by a particular interval, the follower goes up by that same interval (Kennedy 1994).

Retrograde or crab canon

In a retrograde canon, also known as a canon cancrizans (Latin for crab canon, derived from the Latin cancer = crab), the follower accompanies the leader backward (in retrograde). Alternative names for this type are canon per recte et retro or canon per rectus et inversus (Kennedy 1994).

Mensuration and tempo canons

In a mensuration canon (also known as a prolation canon, or a proportional canon), the follower imitates the leader by some rhythmic proportion. The follower may double the rhythmic values of the leader (augmentation or sloth canon) or it may cut the rhythmic proportions in half (diminution canon). Phasing involves the application of modulating rhythmic proportions according to a sliding scale. The cancrizans, and often the mensuration canon, take exception to the rule that the follower must start later than the leader; that is, in a typical canon, a follower cannot come before the leader (for then the labels 'leader' and 'follower' should be reversed) or at the same time as the leader (for then two lines together would constantly be in unison, or parallel thirds, etc., and there would be no counterpoint), whereas in a crab canon or mensuration canon the two lines can start at the same time and still respect good counterpoint.

Many such canons were composed during the Renaissance, particularly in the late fifteenth and early sixteenth centuries; Johannes Ockeghem wrote an entire mass (the Missa prolationum) in which each section is a mensuration canon, and all at different speeds and entry intervals. In the 20th century, Conlon Nancarrow composed complex tempo or mensural canons, mostly for the player piano as they are extremely difficult to play. Larry Polansky has an album of mensuration canons, Four-Voice Canons. Arvo Pärt has written several mensuration canons, including Cantus in Memoriam Benjamin Britten, Arbos and Festina Lente. Per Nørgård's infinity series has a sloth canon structure (Mortensen n.d.). This self-similarity of sloth canons makes it "fractal like" and the same idea is explored in Fractal Tune Smithy's Sloth Canons

Other types of canon

The most familiar of the canons is the perpetual/infinite canon (in Latin: canon perpetuus) or round. As each voice of the canon arrives at its end it can begin again, in a perpetuum mobile fashion; e.g., "Three Blind Mice". Such a canon is also called a round or, in medieval Latin terminology, a rota. Sumer is icumen in is one example of a piece designated rota.

Additional types include the spiral canon, accompanied canon, and double or triple canon. A double canon is a canon with two simultaneous themes, a triple canon has three.

Mirror canon

Main article: Mirror canon

In a mirror canon (or canon by contrary motion), the subsequent voice imitates the initial voice in inversion. They are not very common, though examples of mirror canons can be found in the works of Bach, Mozart (e.g., the trio from Serenade for Wind Octet in C, K. 388), Webern, and other composers.

Table canon

Main article: Table canon

A Table canon is a retrograde and inverse canon meant to be placed on a table in between two musicians, who both read the same line of music in opposite directions. As both parts are included in each single line, a second line is not needed. Bach wrote a few table canons (Benjamin 2003, 120).

Rhythmic canon

Olivier Messiaen employed a technique which he called "rhythmic canon", a polyphony of independent strands in which the pitch material differs. An example is found in the piano part of the first of the Trois petites liturgies de la présence divine, where the left hand (doubled by strings and maracas), and the right hand (doubled by vibraphone) play the same rhythmic sequence in a 3:2 ratio, but the right hand adapts a sequence of 13 chords in the sixth mode (B-C-D-E-F-F-G-A-B) onto the 18 duration values, while the left hand twice states nine chords in the third mode (Griffiths 2001).

Puzzle canon

A puzzle canon (also known as Rätsel-Kanon or canon aenigmaticus) is a canon in which only one voice is notated and the rules for determining the remaining parts and the time intervals of their entrances must be guessed (Merriam-Webster n.d.). Clues hinting at the solution may be provided by the composer, in which case the term "riddle canon" can be used (Scholes, Nagley, Whittall, and Latham n.d.). J S Bach presented many of his canons in this form, for example in The Musical Offering. Other notable contributors to the genre include Ciconia, Ockeghem, Byrd, Dowland, Mozart, Beethoven, Mendelssohn, Brahms, Stravinsky, Schoenberg, Nono and Maxwell Davies.

Elaborate use of canon technique

Contemporary canons

In his early work, such as Piano Phase (1967) and Clapping Music (1972), Steve Reich used a process he calls phasing which is a "continually adjusting" canon with variable distance between the voices, in which melodic and harmonic elements are not important, but rely simply on the time intervals of imitation (Mann, Wilson, and Urquhart n.d.).

Media
J S Bach: Canon per augmentationem contrario motu
(Midi)
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See also

References

Further reading

External links