Heptatonic scale

3.8

"Hepta" from Greek means "seven" and so:

A heptatonic scale is a scale composed of seven notes.

There are many seven note scales. In contemporary standard Western music, for examples, there are twelve notes (A, A#/Bb, B, C, C#/Db, D, D#/Eb, E, F, F#/Gb, G, G#/Ab, which divide an octave in twelve semitones) and so there are many seven note combinations in between.

The standard major scale, for example, is a heptatonic scale. The major scale in C is C, D, E, F, G, A, B and is a heptatonic scale because it consists of seven notes.

Primary heptatonic scale ("heptonia prima")

Primary heptatonic scales, also known as "heptonia prima" or the "diatonic scale", use only half- and full- steps (semitones and tones) between adjacent notes and spread the half-steps most evenly(half-steps occur only twice and there are always either two or three full steps between the two half-steps).

The natural minor and the major scales are primary heptatonic scales. The major scale in C, for example, is C, D, E, F, G, A, B. The steps between these notes are 1, 1, ½, 1, 1, 1, ½. There are two intervals of one semitone – between E and F and between B and C. Going up from F we will find three intervals of two semitones – between F and G, between G and A, and between A and B – before we get to the next interval of one semitone. If we go up from C, we will count two intervals of two semitones – between C and D and between D and E – before we get to the next interval of one semitone.

Modes of the primary heptatonic scale

Taking the notes of the major C scale example above, we can build one different heptatonic scale by starting from each of the different notes. We will get the following modes.

Ionian mode, also known as "major", built on the tonic of the major scale (the first note), with steps 1, 1, ½, 1, 1, 1, ½ (C, D, E, F, G, A, B in this example)

Dorian mode, built on the supertonic of the major scale (the second note), with steps 1, ½, 1, 1, 1, ½, 1, the only one symmetric going up and down (D, E, F, G, A, B, C in this example)

Phrygian mode, built on the mediant of the major scale (the third note), with steps ½, 1, 1, 1, ½, 1, 1 (E, F, G, A, B, C, D in this example)

Lydian mode, built on the subdominant of the major scale (the fourth note), with steps 1, 1, 1, ½, 1, 1, ½ (F, G, A, B, C, D, E in this example)

Mixolydian mode, built on the dominant of the major scale (the fifth note), with steps 1, 1, ½, 1, 1, ½, 1 (G, A, B, C, D, E, F in this example)

Aeolian mode, also known as "natural minor" or the "melodic descending minor", built on the submediant of the major scale (the sixth note), with steps 1, ½, 1, 1, ½, 1, 1 (A, B, C, D, E, F, G in this example)

Locrian mode, built on the leading tone of the major scale (the seventh note), with steps ½, 1, 1, ½, 1, 1, 1 (B, C, D, E, F, G, A in this example)

Secondary heptatonic scale ("heptonia secunda")

The difference between these scales and the primary heptatonic scales is that the secondary heptatonic scales allow one or four full steps between two occurrences of half-steps (and not two or three full-step intervals as with the primary heptatonic scale). The melodic ascending minor is an example of a secondary heptatonic scale. The melodic ascending minor scale in C, for example, is C, D, Eb, F, G, A, B. Going up from C we will find one interval of two semitones – between C and D – before we get to an interval of one semitone. Going up from Eb we will find four intervals of two semitones – between Eb and F, between F and G, between G and A, and between A and B – before we get to an interval of one semitone.

Modes of the secondary heptatonic scale

Similarly to primary heptatonic scales, models can be built by starting from each of the notes in the melodic ascending minor on C shown above. The modes would be as follows.

Melodic ascending minor mode, with steps 1, ½, 1, 1, 1, 1, ½ (C, D, Eb, F, G, A, B in this example)

Phrygian mode with a raised sixth, with steps ½, 1, 1, 1, 1, ½, 1 (D, Eb, F, G, A, B, C in this example)

Lydian mode with a raised fifth, with steps 1, 1, 1, 1, ½, 1, ½ (Eb, F, G, A, B, C, D in this example)

Lydian-Mixolydian mode, also known as "acoustic", with steps 1, 1, 1, ½, 1, ½, 1 (F, G, A, B, C, D, Eb in this example)

Minor with a raised third mode, thus also known as "major-minor", with steps 1, 1, ½, 1, ½, 1, 1 (G, A, B, C, D, Eb, F in this example)

Locrian with a raised second, with steps 1, ½, 1, ½, 1, 1, 1 (A, B, C, D, Eb, F, G in this example)

Locrian with a flat fourth, also known as "altered", with steps ½, 1, ½, 1, 1, 1, 1 (B, C, D, Eb, F, G, A in this example)

The reason the secondary heptatonic scales are used less often is that they allow for augmented and diminished chords. For example, because of the four adjacent full steps, the natural melodic minor C, D, Eb, F, G, A, B produces the Eb augmented chord Eb, G, B, the G augmented chord G, B, Eb, and the B augmented chord B, Eb, G. All of these chords contain the same notes and hence obviously do not offer a clearly defined tonal center.

Tertiary heptatonic scale ("heptonia tertia")

Tertiary heptatonic scales have two adjacent half-step intervals and hence also five adjacent full-step intervals. For example, such a scale could have the steps ½, ½, 1, 1, 1, 1, 1.

Other heptatonic scales

Note that primary, secondary, and tertiary heptatonic scales use only intervals of one semitone (½ step and 1 step (two semitones) between adjacent notes. Other heptatonic scales can be formed by allowing intervals other than ½ and 1, as for example, the 1½ step interval (three semitones) , known as the "augmented second". The following are examples of other common heptatonic scales.

Harmonic minor, Spanish gypsy: Take the natural minor scale and raise the seventh degree. The resulting scale will have the steps 1, ½, 1, 1, ½, 1½, ½ (for example, A, B, C, D, E, F, G#). This scale is known as the "harmonic minor scale". The fifth mode of this same scale has the steps ½, 1½, ½, 1, ½, 1, 1 and is known as the "Spanish gypsy scale" (for example, E, F, G#, A, B, C, D).

Minor gypsy: Take the natural minor scale and raise the fourth note on the scale. The resulting scale will have the steps 1, ½, 1½, ½, ½, 1, 1 (for example, A, B, C, D#, E, F, G). It is known as the “minor gypsy scale”.

Hungarian, Egyptian, gypsy, double harmonic major: Take the natural minor scale and raise both the fourth and seventh note. You will get a scale with the steps 1, ½, 1½, ½, ½, 1½, ½ (for example, A, B, C, D#, E, F, G#). This scale is known as the "Hungarian scale". The fifth mode of this scale is ½, 1½, ½, 1, ½, 1½, ½ and is also known as the Byzantine scale (for example, E, F, G#, A, B, C, D#). The names Egyptian, gypsy, and double harmonic major are used interchangeably for this scale as well.

Major flat 6: Take the major scale and lower the sixth of the scale to get the steps 1, 1, ½, 1, ½, 1½, ½ (for example, C, D, E, F, G, Ab, B). This is known as the "major flat 6 scale".

Enigmatic scale: The "enigmatic" scale has the steps ½, 1½, 1, 1, 1, ½, ½ (for example, C, Db, E, F#, G#, A#, B).

Quarter tone heptatonic scales

The scales shown above use semitones (½ step), tones (1 step), and augmented second intervals (1½ steps). Heptatonic scales could also use quarter tone intervals (¼ step), which are less typical for Western scales, but extend the number of possibilities. Examples of quarter tone scales are Bayati, Rast, [[Sabba scale|Sabba], and Siga.

Notes (degrees) in a heptatonic scale

The first, second, and so on notes on the heptatonic scale in order carry the names: 1) tonic; 2) supertonic; 3) mediant; 4) subdominant; 5) dominant; 6) submediant; and 7) leading tone in general or subtonic for the lowered 7th on the natural minor scale.

See also:
Scale, Scale (index)



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