Scale Mutation
• Transposition: root moves, scale type retained
(see Debussy, Cathédrale mm.14-16, transposes the pentatonic scale)
• Scale Type Changes: movement from Whole-Tone to Pentatonic (both with
Bb pedal)
(see Debussy, “Voiles” m. 44 to m. 45)
• Transposition and Scale change: both of the above occur
very common (see Debussy Cathédrale mm.1-13)
Common-Tone Scale Mutation
• At least one pitch in common between two temporally adjacent scales
(see Debussy Cathédrale m.1 pentatonic has [E] in common with m.7
minor pentatonic)
Also:
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Tetrachords and Scale Synthesis
• Break scales into characteristic four note collections
Minor tetrachord:
1st tetrachord in: dorian, aeolian, minor,
and Model B octatonic scales
Major tetrachord:
1st tetrachord of ionian and mixolydian sacles
Phrygian Tetrachord:
1st tetrachord of locrian and phrygian scales
Lydian/Whole-Tone Tetrachord:
1st tetrachord of lydian and whole-tone scales,
2nd tetrachord of locrian scale
Octatonic Model A Tetrachord:
(may be found in any Octatonic scale)
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Harmonic Minor Tetrachord:
2nd tetrachord of harmonic minor scale
and found in Bartók’s “Hungarian” scales
•
Scale synthesis involves conjoining two tetrachords. The interval between the
tetrachords is referred to as the interval of conjunction usually a m2 or M2.
[Tetrachord 1] !m2 or M2" [Tetrachord 2]
•
Phrygian mode may be understood as follows:
[Phrygian Tetrachord] !M2" [T7(Phrygian Tetrachord)]
or
[0,1,3,5] + [7,8,10,0]
•
Atypical combinations such as:
[Lydian Tetrachord] !m2" [T7(Harmonic minor tetrachord)]
or
[0,2,4,6] + [7,8,11,0]
may be described as the synthesis of tetrachords characteristic of Lydian
and harmonic minor
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