Mode
In the modern western understanding of scales, a mode (or rotation) of a periodic scale is an ordering of the scale's tones determined by choosing one of the tones as the starting/ending point.
For example, the diatonic material 0 2 4 5 7 9 11 12 14 16 17 ... of 12edo with its 7-tone periodicity (12 equals 0) can be used to build 7 different modes, which are often named as:
- Ionian (0...)
- Dorian (2...)
- Phrygian (4...)
- Lydian (5...)
- Mixolydian (7...)
- Aeolian (9...)
- Locrian (11...)
Modes are mostly used in the context of tonal or modal music, i.e. as opposed to atonal music, since their definition implies a pitch center.
Properties
A scale has as many modes as the number of tones that it contains within a period. For example:
- the diatonic scale has 7 modes, because it has 7 tones per period of 1 octave;
- the octatonic diminished scale only has 2 modes, because it has 2 tones per period of 1/4 octave.
In an equal-step tuning, any mode of any supported scale can be built on any tone of the chosen tuning, i.e. it is possible to transpose to any key while keeping the same scale and mode.