Heptatonic scale
A heptatonic scale is a musical scale that has seven pitches, or tones, per octave. Examples include:
- the diatonic scale; including the major scale and its modes
- the melodic minor scale, like the Aeolian mode but with raised 6th and 7th ascending
- the harmonic minor scale, like the Aeolian mode but with raised 7th
- the harmonic major scale, like the major scale but with lowered 6th
Several heptatonic scales in Western, Roman, Spanish, Hungarian, and Greek music can be analyzed as juxtapositions of tetrachords. All heptatonic scales have all intervals present in their interval vector analysis, and thus all heptatonic scales are both hemitonic and tritonic. There is a special affinity for heptatonic scales in the Western key signature system.
Diatonic scale
A [|diatonic scale] is any seven-note scale constructed sequentially using only whole tones and half tones, repeating at the octave, having a tonal center, and comprising only one tritone interval between any two scale members, which ensures that the half tone intervals are as far apart as possible. In Western music, there are seven such scales, and they are commonly known as the modes of the major scale.Melodic minor scale
In traditional classical theory, the melodic minor scale has two forms, as noted above, an ascending form and a descending form. Although each of these forms of itself comprises seven pitches, together they comprise nine, which might seem to call into question the scale's status as a heptatonic scale. In certain twentieth-century music, however, it became common systematically to use the ascending form for both ascending and descending passages. Such a use has been notably ascribed to the works of Béla Bartók and to bop and post-bop jazz practice. The traditional descending form of the melodic minor scale is equivalent to the natural minor scale in both pitch collection and tonal center.Harmonic minor scale
The [|harmonic minor scale] is so called because in tonal music of the common practice period chords or harmonies are derived from it more than from the natural minor scale or the melodic minor scale. The augmented second between its sixth degree and its raised seventh degree, traditionally considered undesirable in melodic progression, is avoided by placing these pitches in different voices in adjacent chords, as in this progression: F A D, F G B, F A C. The A in the middle voice does not ascend to B, and the B in the upper voice does not descend to A.Heptatonia prima and secunda
The names heptatonia prima and heptatonia secunda apply to seven-note scales that can be formed using five tones and two semi-tones, also called whole-steps and half-steps, but without two semi-tones in succession. Throughout history and to the present day, some have occurred much more commonly than others, namely Ionian, Aeolian, melodic ascending minor, Dorian, Mixolydian, Lydian, Lydian dominant, Aeolian dominant, and altered scales.Heptatonia prima
In these scales the semi-tones are maximally separated. They are known most commonly as the diatonic modes. Beginning on keynote C and working up the notes of the 'major' scale, the seven modes are:[Image:Ionian mode C.png|thumb|left|Ionian mode C ]
- Ionian mode t-t-s-t-t-t-s
- Dorian mode t-s-t-t-t-s-t
- Phrygian mode s-t-t-t-s-t-t
- Lydian mode t-t-t-s-t-t-s
- Mixolydian mode t-t-s-t-t-s-t
- Aeolian mode t-s-t-t-s-t-t
- Locrian mode s-t-t-s-t-t-t
Heptatonia secunda
While the diatonic modes have two and three tones on either side of each semitone, the heptatonia secunda modes have one and four.These are sometimes called modes of the melodic ascending minor since that is the most commonly used scale of this type, but other modes can be produced by starting on the different scale notes in turn.
Thus starting on keynote A as above and following the notes of the ascending melodic minor yields these seven modes:
[Image:Amoll.melod.auf.png|thumb|right|Ascending melodic minor scale on A ]
- Ascending melodic minor scale t-s-t-t-t-t-s
- Dorian ♭2 scale or Phrygian 6 scale s-t-t-t-t-s-t combines the Phrygian flat second and Dorian raised sixth
- Lydian augmented scale t-t-t-t-s-t-s combines the Lydian fourth with a raised fifth
- Acoustic scale or Lydian dominant scale t-t-t-s-t-s-t So-called because it is close to the scale built on natural overtones and combines Lydian raised fourth with Mixolydian flat seventh
- Aeolian dominant scale or Mixolydian 6 scale t-t-s-t-s-t-t Like natural minor but with a major third
- Half diminished scale t-s-t-s-t-t-t This is like the Locrian with a raised second
- Altered scale s-t-s-t-t-t-t Like Locrian with diminished fourth
Heptatonia tertia
Image:Neapolitan major scale on C.png|thumb|right|Neapolitan major scale on CThe last group of seven-note tone/semitone scales is heptatonia tertia, and consists of scales with two adjacent semitones—which amounts to a whole-tone scale, but with an additional note somewhere in its sequence, e.g., B C D E F G A. One such example is the Neapolitan major scale.
Other heptatonic scales
[Image:Gypsy Minor Scale.png|thumb|Hungarian Gypsy scale]If the interval of the augmented second is used, many other scales become possible. These include
Gypsy I-II-III-IV-V-VI-VII
Hungarian I-II-III-IV-V-VI-VII
The scales are symmetrical about the tonic and dominant respectively and the names are sometimes used interchangeably.
The double harmonic scale, also known as the Byzantine or Hungarian, scale, contains the notes C D E F G A B C.
Image:C Phrygian dominant scale.svg|thumb|Phrygian dominant scale, also known as persian scale
Phrygian dominant or dominant harmonic minor I-II-III-IV-V-VI-VII
This differs from the Phrygian in having a major third. It may also be considered built on the dominant of the harmonic minor scale.
Neapolitan minor differs from the Phrygian in having a major seventh.
[Image:Enigmatic scale on C.png|thumb|Enigmatic scale on C ]
Verdi's Scala Enigmatica I-II-III-IV-V-VI-VII i.e. G A B C D E F, which is similar to the heptatonia tertia mentioned above, differing only in that the second degree here is flattened.