Minor scale
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A minor scale in musical theory is a diatonic scale whose third scale degree is an interval of a minor third above the tonic. While some definitions of minor scale encompass modes with the minor third, such as Dorian mode, most musicians use the term to refer to the natural minor, harmonic minor, and melodic minor scales described below. Also, compare major and minor. It is helpful to note that the natural minor scale is the same as the 6th musical mode of the major scale (known as the aeolian mode), but the two other minor scales (harmonic and melodic) do not belong to the same group of modes due to their individual alterations.
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[edit] Types of minor scales
A natural minor scale has the following interval pattern:
tone, semitone, tone, tone, semitone, tone, tone
In equal temperament, this can be equated to
whole-step, half-step, whole-step, whole-step, half-step, whole-step, whole step.
In the classic major scale, the steps are: 1 -W- 2 -W- 3 -H- 4 -W- 5 -W- 6 -W- 7 -H- 8.
One way of remembering the steps in the natural minor scale is to start on the 6th degree of the relative major scale. In that way, one does not have to remember the new set of steps "W,H,W,W,H,W,W," but rather just the familiar major scale steps with a different starting point. For example, A is the 6th scale note of the C major scale, so the A natural minor scale is just the C major scale starting on the 6th scale note.
The C major scale is C D E F G A B C, so the A natural minor scale is A B C D E F G A (A is the 6th scale note of the C major scale)
In other meantone tunings the semitone is not half of a tone, but a somewhat larger interval.
If the scale is used with the corresponding key signature, the natural minor scale is written with no accidentals.
For example, in the key of A minor, the natural minor scale is:
A B C D E F G A'
Sometimes the natural minor scale is equated with the Aeolian mode, but a key characteristic of music in the minor mode in the common practice period of Western music is the use of the leading tone, a half step below the tonic. Music using the natural seventh degree, called the subtonic, sounds modal to Western ears; this music is commonly used in Peruvian and other ethnic music, and by modern Western composers such as Vaughan Williams who have a liking for this sound. Also, in music written from the 16th to 19th centuries, the chord built on the dominant (fifth scale degree) is almost always a major triad, at least at cadence points; consequently, the seventh degree of the scale must be raised with an accidental to make this possible. The next most important chord, the subdominant, is typically a minor triad.
These considerations of harmony lead to the harmonic minor scale, the same as the natural minor but with a chromatically raised seventh degree.
tone semitone tone tone semitone tone-and-a-half semitone
For example, in the key of A minor, the harmonic minor scale is:
A B C D E F G♯ A'
The interval between the sixth and seventh degrees of this scale (in this case F and G sharp) is an augmented second. While some composers, notably Mozart, have used this interval to advantage in melodic composition, other composers have felt it to be an awkward leap, particularly in vocal music. Thus, for purposes of melody, either the subtonic is used, or the sixth scale degree is raised; either way, there is a whole step between these two scale degrees, considered more conducive to smooth melody writing.
Traditionally, music theorists have called these two options the ascending melodic (also known as heptatonia seconda, set form 7-34) and descending melodic minor scales:
but historically, composers have not been consistent about using them 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). Another reason might be the use of the mediant chord, based on the third degree of the scale, which is an augmented triad if the raised seventh degree is used; some composers prefer the use of the major triad and thus use the lowered seventh degree.
[edit] Finding key signatures
Minor modes use the same set of key signatures as major modes; whichever signature corresponds to the step pattern of the natural minor scale is considered the key signature for that minor mode. The major and minor keys which share the same signature are called relative; so C major is the relative major of A minor, and C minor is the relative minor of E-flat major.
The relative major is found by raising the minor tonic note by a tone and a semitone, which is three half-steps in equal temperament, and in any event an interval of a minor third. If you know that the key signature of G major has one sharp (see major scales for how to find this), then its relative minor, E minor, also has one sharp in its key signature.
This table illustrates the relative major key signatures for minor scales.
| Key Sig. | Major Scale | Minor Scale | ||
|---|---|---|---|---|
| 0♯/♭ | C major | a minor | ||
| 1♯ | G major | e minor | ||
| 2♯ | D major | b minor | ||
| 3♯ | A major | f♯ minor | ||
| 4♯ | E major | c♯ minor | ||
| 5♯ | B major | g♯ minor | ||
| 6♯ | F♯ major | d♯ minor | ||
| 7♯ | C♯ major | a♯ minor |
| Key Sig. | Major Scale | Minor Scale | ||
|---|---|---|---|---|
| 1♭ | F major | d minor | ||
| 2♭ | B♭ major | g minor | ||
| 3♭ | E♭ major | c minor | ||
| 4♭ | A♭ major | f minor | ||
| 5♭ | D♭ major | b♭ minor | ||
| 6♭ | G♭ major | e♭ minor | ||
| 7♭ | C♭ major | a♭ 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 |
Additional note: it is possible to construct scales which cannot be written purely using a key signature, such as D-flat minor; double sharps/double flats can be written as accidentals, but not as part of a key signature. For example:
D♭ Minor Key Signature: B♭ + E♭ + A♭ + D♭ + G♭ + C♭ + F♭ + B♭♭ (the B♭ is now double flatted)
D♭ Natural Minor = D♭ E♭ F♭ G♭ A♭ B♭♭ C♭ D♭
D♭ Melodic Minor (Ascending + 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♭
On rare occasions, short passages of music will be written in an enharmonic scale (in this case, C-sharp minor, which only has four sharps in its key signature, compared to the theoretical eight flats required for D-flat minor).
[edit] Circles of thirds
All three of the variant forms of the minor scale possess a complete circle of three major and four minor thirds in various arrangements. If M is a major third and m a minor third, then starting from the tonic (eg A in A minor) we have mmMmmMM for the natural minor scale, mmMmMMm for the harmonic minor scale, and mmMMMmm for the ascending melodic minor. The major diatonic scale is simply a transposition of the natural minor scale, and the harmonic major scale is an inverted form of the harmonic minor scale, so all of these workhorse scales of the diatonic system possess such a circle of thirds. These circles only close in meantone tunings, since three major and four minor thirds exceed two octaves by 81/80, the syntonic comma, in just intonation.
[edit] See also
[edit] Reference
- Gjerdingen, Robert O. (1990). "A Guide to the Terminology of German Harmony", Studies in the Origin of Harmonic Tonality by Dahlhaus, Carl, trans. Gjerdingen (1990).
