Period (music)

In music, period refers to certain types of recurrence in small-scale formal structure. In twentieth-century music scholarship, the term is usually used as defined by the Oxford Companion to Music: "a period consists of two phrases, antecedent and consequent, each of which begins with the same basic motif." Earlier usage varied somewhat, but usually referred to a similar notions of symmetry, recurrence, and closure. The concept of a musical period originates in comparisons between music structure and rhetoric at least as early as the 16th century.

In Western art music or Classical music, a period is a group of phrases consisting usually of at least one antecedent phrase and one consequent phrase totaling about 8 measures in length (though this varies depending on meter and tempo). Generally, the antecedent ends in a weaker and the consequent in a stronger cadence; often, the antecedent ends in a half cadence while the consequent ends in an authentic cadence. Frequently, the consequent strongly parallels the antecedent, even sharing most of the material save the final measures. In other cases, the consequent may differ greatly (for example, the period in the beginning of the second movement of the Pathetique Sonata).

The 1958 Encyclopédie Fasquelle defines a period as follows:

Another definition is as follows:

And

A double period is, "a group of at least four phrases...in which the first two phrases form the antecedent and the third and fourth phrases together form the consequent."

When analyzing Classical music, contemporary music theorists usually employ a more specific formal definition, such as the following by William Caplin:

The second definition of period in the New Harvard Dictionary of Music states: "A musical element that is in some way repeated," applying "to the units of any parameter of music that embody repetitions at any level." In some sub-Saharan music and music of the African diaspora, the bell pattern embodies this definition of period. The bell pattern (also known as a key pattern,guide pattern,phrasing referent,timeline, or asymmetrical timeline) is repeated throughout the entire piece, and is the principal unit of musical time and rhythmic structure by which all other elements are arranged. The period is often a single measure (four main beats).

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