Augmented interval

In Western music and music theory, the word augmentation (from Late Latin augmentare, to increase) has three distinct meanings. Augmentation is a compositional device where a melody, theme or motif is presented in longer note-values than were previously used. Augmentation is also the term for the proportional lengthening of the value of individual note-shapes in older notation by coloration, by use of a sign of proportion, or by a notational symbol such as the modern dot. A major or perfect interval that is widened by a chromatic semitone is an augmented interval, and the process may be called augmentation.

A melody or series of notes is augmented if the lengths of the notes are prolonged; augmentation is thus the opposite of diminution, where note values are shortened. A melody originally consisting of four quavers (eighth notes) for example, is augmented if it later appears with four crotchets (quarter notes) instead. This technique is often used in contrapuntal music, as in the "canon by augmentation" ("per augmentationem"), in which the notes in the following voice or voices are longer than those in the leading voice, usually twice the original length. The music of Johann Sebastian Bach provides examples of this application. Other ratios of augmentation, such as 1:3 (tripled note values) and 1:4 (quadrupled note values), are also possible.

A motif is also augmented through expanding its duration.

Augmentation may also be found in later, non-contrapuntal pieces, such as the Pastoral Symphony (Symphony No. 6) of Beethoven, where the melodic figure heard twice in the last ten bars of the "Storm" movement ("Die Sturm") is an augmented and transposed version of the motif first heard in the second violins in the third bar, or the development sections of sonata form movements, particularly in the symphonies of Brahms and Bruckner.

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