Augmented fifth
Encyclopedia
In classical music
Classical music
Classical music is the art music produced in, or rooted in, the traditions of Western liturgical and secular music, encompassing a broad period from roughly the 11th century to present times...

 from Western culture
Western culture
Western culture, sometimes equated with Western civilization or European civilization, refers to cultures of European origin and is used very broadly to refer to a heritage of social norms, ethical values, traditional customs, religious beliefs, political systems, and specific artifacts and...

, an augmented fifth is an interval
Interval (music)
In music theory, an interval is a combination of two notes, or the ratio between their frequencies. Two-note combinations are also called dyads...

 produced by widening
Augmentation (music)
In Western music and music theory, the word augmentation 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...

 a perfect fifth
Perfect fifth
In classical music from Western culture, a fifth is a musical interval encompassing five staff positions , and the perfect fifth is a fifth spanning seven semitones, or in meantone, four diatonic semitones and three chromatic semitones...

 by a chromatic semitone. For instance, the interval from C to G is a perfect fifth, seven semitones wide, and both the intervals from C to G, and from C to G are augmented fifths, spanning eight semitones. Being augmented, it is considered a dissonant
Consonance and dissonance
In music, a consonance is a harmony, chord, or interval considered stable, as opposed to a dissonance , which is considered to be unstable...

 interval.

Its inversion
Inversion (music)
In music theory, the word inversion has several meanings. There are inverted chords, inverted melodies, inverted intervals, and inverted voices...

 is the diminished fourth
Diminished fourth
In classical music from Western culture, a diminished fourth is an interval produced by narrowing a perfect fourth by a chromatic semitone. For example, the interval from C to F is a perfect fourth, five semitones wide, and both the intervals from C to F, and from C to F are diminished fourths,...

, and its enharmonic
Enharmonic
In modern musical notation and tuning, an enharmonic equivalent is a note , interval , or key signature which is equivalent to some other note, interval, or key signature, but "spelled", or named, differently...

 equivalent is the minor sixth
Minor sixth
-Subminor sixth:In music, a subminor sixth or septimal sixth is an interval that is noticeably narrower than a minor sixth but noticeably wider than a diminished sixth.The sub-minor sixth is an interval of a 14:9 ratio or alternately 11:7....

.

The augmented fifth only began to make an appearance at the beginning of the common practice period
Common practice period
The common practice period, in the history of Western art music , spanning the Baroque, Classical, and Romantic periods, lasted from c. 1600 to c. 1900.-General characteristics:...

 of music as a consequence of composers seeking to strengthen the normally weak seventh degree when composing music in minor modes.

This was achieved by chromatically
Chromatic scale
The chromatic scale is a musical scale with twelve pitches, each a semitone apart. On a modern piano or other equal-tempered instrument, all the half steps are the same size...

 raising the seventh degree (or subtonic
Subtonic
In music, the subtonic or flattened seventh is the lowered or minor seventh degree of the scale, a whole step below the tonic, as opposed to the leading tone...

) to match that of the unstable seventh degree (or leading tone) of the major mode (an increasingly widespread practice that led to the creation of a modified version of the minor scale
Minor scale
A minor scale in Western music theory includes any scale that contains, in its tonic triad, at least three essential scale degrees: 1) the tonic , 2) a minor-third, or an interval of a minor third above the tonic, and 3) a perfect-fifth, or an interval of a perfect fifth above the tonic, altogether...

 known as the harmonic minor scale).

A consequence of this was that the interval between the minor mode's already lowered third degree (mediant
Mediant
In music, the mediant is the third scale degree of the diatonic scale, being the note halfway between the tonic and the dominant. Similarly, the submediant is halfway between the tonic and subdominant...

) 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
Augmented triad
In music, an augmented triad is a triad, or chord, consisting of two major thirds . The term augmented triad arises from an augmented triad being a three note chord, or triad, whose top note is raised, or augmented...

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
Jazz
Jazz is a musical style that originated at the beginning of the 20th century in African American communities in the Southern United States. It was born out of a mix of African and European music traditions. From its early development until the present, jazz has incorporated music from 19th and 20th...

 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
Equal temperament
An equal temperament is a musical temperament, or a system of tuning, in which every pair of adjacent notes has an identical frequency ratio. As pitch is perceived roughly as the logarithm of frequency, this means that the perceived "distance" from every note to its nearest neighbor is the same for...

 tuning, an augmented fifth is equal to eight semitones, a ratio of 22/3:1 (about 1.587:1), or 800 cents
Cent (music)
The cent is a logarithmic unit of measure used for musical intervals. Twelve-tone equal temperament divides the octave into 12 semitones of 100 cents each...

.

The augmented fifth is a context-dependent dissonance
Consonance and dissonance
In music, a consonance is a harmony, chord, or interval considered stable, as opposed to a dissonance , which is considered to be unstable...

. 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
Consonance and dissonance
In music, a consonance is a harmony, chord, or interval considered stable, as opposed to a dissonance , which is considered to be unstable...

 enharmonic equivalent, the minor sixth.
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