In Western music theory, minor scale may refer to:
- a heptatonic scale whose first, third, and fifth scale degrees form a minor triad, that is, a 7-note scale in which the third note is a minor third (three semitones) above the first, and the fifth note is a perfect fifth (seven semitones) above the first. This includes the natural minor, harmonic minor, and melodic minor scales. A minor scale differs from a major scale in that the third degree in a major scale is a major third (four semitones) above the first degree. In other words, the third degree in a major scale is one semitone higher than in a minor scale.
- the natural minor scale, also known as Aeolian scale, taken by itself. When a major scale and a natural minor scale have the same key signature, they are relative keys. A natural minor scale has the same notes as its relative major scale, but is built starting from the sixth note of the relative major scale.
- the functional fusion of natural minor, harmonic minor, and melodic minor scales, as is used in Western classical music (see major and minor). A harmonic minor scale differs from a natural minor scale in that the seventh note is raised one semitone. Melodic minor scales raise both the sixth and seventh notes one semitone when ascending, but when descending, the sixth and seventh notes are flattened, producing the natural minor scale.
Natural minor scale
The natural minor scale follows the sequence of steps:
- whole, half, whole, whole, half, whole, whole
In semitones, this is
- two, one, two, two, one, two, two (2 1 2 2 1 2 2)
If the white keys on the piano are played beginning on the sixth step of the C major scale, which is A, to the A an octave above, then a natural minor scale is produced. In this case the minor scale is called A minor, and this minor scale has no accidentals (sharps or flats). A minor is called the relative minor of C. Every major key has a relative minor, which starts on the sixth scale degree or step.
The natural minor scale can also be represented by the notation:
- 1 2 ♭3 4 5 ♭6 ♭7 8
Each degree of the scale, starting with the tonic (the first, lowest note of the scale), is represented by a number. Their difference from the major scale is shown. Thus a number without a sharp or flat represents a major (or perfect) interval. A number with a flat represents a minor interval, and a number with a sharp (though there are none in this example) represents an augmented interval. In this example, the numbers mean: 1=unison, 2=major second, ♭3=minor third, 4=perfect fourth, 5=perfect fifth, ♭6=minor sixth, ♭7=minor seventh, 8=octave. So, the natural minor scale consists of: 1, the tonic, followed by 2, a note a major second above the tonic, ♭3, a note a minor third above the tonic, and so forth, up to 8, a note an octave above the tonic.
The natural minor scale is equivalent to the Aeolian mode, although scales and modes are built upon different systems and are technically not the same.
Harmonic minor scale
The notes of the harmonic minor scale are the same as the natural minor except that the seventh degree is raised by one semitone, making an augmented second between the sixth and seventh degrees. The seventh degree, in a similar way to major scales, becomes a leading tone to the tonic because it is now only a semitone lower than the tonic, in contrast to the seventh degree in natural minor scales, which are a whole tone lower than the tonic (subtonic). A harmonic minor scale follows the sequence of steps:
- whole, half, whole, whole, half, whole-and-a-half, half
In semitones, this is
- two, one, two, two, one, three, one (2 1 2 2 1 3 1)
This can also be notated as:
- 1 2 ♭3 4 5 ♭6 7 8.
The scale is so named because it is a common foundation for harmonies (chords) used in a minor key. For example, in the key of A minor, the V chord (the triad built on the note E) is normally a major triad that includes the raised seventh degree of the scale: G♯, as opposed to the unraised G♮ which would make a minor triad.
Chords on degrees other than V may also include the raised seventh degree in minor keys, such as the diminished triad on VII itself (viio); and also the augmented triad on III (iii+), which is not found in any "natural" harmony (that is, harmony based on notes of the major scale only, or the natural minor scale only). This augmented fifth chord (♯5 chord) played a part in the development of modern chromaticism.
The inversions of an augmented triad introduce no intervals (allowing for enharmonic equivalents) that are absent from its root position. The first inversion is enharmonically equivalent to a new augmented triad in root position. For example, the triad E♭–G–B in first inversion is G–B–E♭, enharmonically equivalent to the augmented triad G–B–D♯. The same is true for the second inversion. One chord, with various spellings, may therefore have various harmonic functions in various keys, which introduces ambiguous tonality and opens the door to chromatic possibilities exploited by J. S. Bach, for example, and of course by many later composers. A similar analysis applies to the diminished seventh chord, founded on the diminished triad on VII in minor keys and ambiguous for the same reasons as the augmented triad.
While it evolved primarily as a basis for chords, the harmonic minor with its augmented second is sometimes used melodically. Instances can be found in Mozart, and notably in Schubert (for example, in movement 1 of String Quartet 14, "Death and the Maiden"). In this role it is used descending far more commonly than ascending.
The harmonic minor is also occasionally referred to as the Mohammedan scale as its upper tetrachord corresponds to the Hijaz jins, commonly found in Middle Eastern music. The harmonic minor scale as a whole is called Nahawand-Hijaz in Arabic nomenclature, and as Bûselik Hicaz  in Turkish nomenclature. And as an Indian raga it is called Kirwani.
The Hungarian minor scale is similar to the harmonic minor scale but with a raised fourth degree. This scale is sometimes also referred to as "Gypsy Run", or alternatively "Egyptian Minor Scale", as mentioned by jazz legend Miles Davis who describes it in his autobiography as "something that I'd learned at Juilliard".
Melodic minor scale
The distinctive sound of the harmonic minor scale is the interval between the (minor) sixth and (major) seventh degrees of the scale (in the case of A minor, F and G♯), which is an augmented second. While some composers, notably Mozart, have used this interval to advantage in melodic composition, other composers, having felt it to be an awkward leap, particularly in vocal music, considered a whole step between these two scale degrees more conducive to smooth melody writing, so either the sixth scale degree was raised or the seventh flattened, in both cases by a semitone. Traditionally, music theorists have called these two options the ascending melodic minor scale (also known as heptatonia seconda and jazz minor scale) and descending melodic minor scale respectively. The ascending melodic minor scale can be notated as
- 1 2 ♭3 4 5 6 7 8
While the descending is:
- 1 2 ♭3 4 5 ♭6 ♭7 8
In its upper tetrachord, the ascending melodic minor scale is identical to its major scale. The descending melodic minor scale is identical to the natural minor scale.
Composers have not been consistent in using these in ascending and descending melodies. Just as often, composers choose one form or the other based on whether one of the two notes is part of the most recent chord (the prevailing harmony). Particularly, to use the triad of the relative major—which is very common—since this is based on the third degree of the minor scale, the raised seventh degree would cause an augmented triad. Composers thus frequently require the lowered seventh degree found in the natural minor. In jazz, the descending aeolian is usually disregarded altogether.
Examples of the use of melodic minor in rock and popular music include Elton John's "Sorry Seems To Be The Hardest Word", which makes, "a nod to the common practice...by the use of F♯ [the leading-tone in G minor] as the penultimate note of the final cadence."
Finding key signatures
Major and minor keys that share the same signature are relative to each other; so C major is the relative major of A minor, and C minor is the relative minor of E♭ major. The relative major is a minor third above the tonic of the minor. For example, since the key signature of G major has one sharp (see major scales for how to find this), its relative minor, E minor, also has one sharp in its key signature.
Music may be written in an enharmonic scale (e.g. C♯ minor, which only has four sharps in its key signature, compared to the theoretical eight flats required for D♭ minor). The following are enharmonic equivalents:
|Key sig.||Major scale||Minor scale|
|5♯/7♭||B/C♭ major||g♯/a♭ minor|
|6♯/6♭||F♯/G♭ major||d♯/e♭ minor|
|7♯/5♭||C♯/D♭ major||a♯/b♭ minor|
Double sharps/double flats can be written as accidentals, but not as part of a key signature. For example:
D♭ minor key signature: E♭ + A♭ + D♭ + G♭ + C♭ + F♭ + B (the B is now double flatted and therefore, notated after the single accidentals, which obviously do not include the B♭)
D♭ natural minor = D♭ E♭ F♭ G♭ A♭ B C♭ D♭
D♭ melodic minor (ascending and descending) = D♭ E♭ F♭ G♭ A♭ B♭ C D♭ C♭ B A♭ G♭ F♭ E♭ D♭
D♭ harmonic minor = D♭ E♭ F♭ G♭ A♭ B C D♭
In the Western system, derived from the Greek system of modes, the principal scale that includes the minor third is the Aeolian mode, with the minor third also occurring in the Dorian mode and the Phrygian mode. Dorian is the same as minor mode except with a major sixth, and Phrygian mode is the same as minor mode except with a minor second.
- Hewitt, Michael. 2013. Musical Scales of the World. The Note Tree. ISBN 978-0957547001.
- Yamaguchi, Masaya. 2006. The Complete Thesaurus of Musical Scales, revised edition. New York: Masaya Music Services. ISBN 0-9676353-0-6.
- Proper fingering of the major and minor scales on the piano
- Listen to and download harmonised minor scale piano MP3s