- Augmented fifth
Infobox Interval
main_interval_name = augmented fifth
inverse =diminished fourth
complement =diminished fourth
other_names = -
abbreviation = ?
semitones = 8
interval_class = 4
just_interval = 25:16| cents_equal_temperament = 800
cents_just_intonation = 773An augmented fifth (Audio|Minor sixth on C.mid|Play) is a
musical interval that spans five scale degrees and consists of eight semitones. The prefix "augmented" identifies it as being one semitone larger than theperfect fifth . Itsinversion is thediminished fourth , and itsenharmonic equivalent is theminor sixth .The augmented fifth has no
diatonic occurrence, and only began to make an appearance, at the beginning of thecommon practice period of music, as a consequence of composers seeking to strengthen the normally weak seventh degree when composing music inminor mode s.This was achieved by chromatically raising the seventh degree (or
subtonic ) to match that of the unstable seventh degree (orleading tone ) of themajor mode (an increasingly widespread practice that led to the creation of a modified version of theminor scale known as theharmonic minor scale ).A consequence of this was that the interval between the minor mode's already lowered third degree (
mediant ) and the newly raised seventh degree (leading note), previously a perfect fifth, had now been "augmented" by a semitone.Another result of this practice was the appearance of the first
augmented triad s, built on the same (mediant) degree, in place of the naturally occurring major chord.As music became increasingly chromatic, the augmented fifth was used with correspondingly greater freedom and also became a common component of
jazz chords. Near the end of the nineteenth century the augmented fifth became commonly used in a dominant chord. This would create an augmented dominant (or V) chord. The augmented fifth of the chord would then act as a leading tone to the third of the next chord. This augmented V chord would never precede a minor tonic (or i) chord since the augmented fifth of the dominant chord is identical to the third of the tonic chord.In an equal tempered tuning, an augmented fifth is equal to eight semitones, a ratio of 28/12:1 (approximately 1.587), or 800 cents.
The augmented fifth is a context-dependent dissonance. That is, when heard in certain contexts, such as that described above, the interval will sound dissonant. In other contexts, however, the same eight-semitone interval will simply be heard (and notated) as its consonant enharmonic equivalent, the minor sixth.
ee also
*
List of meantone intervals
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