Aeolian is the natural minor scale (W-H-W-W-H-W-W), built on the sixth degree of the major scale. Locrian, built on the seventh degree, is the most unstable mode because it has a diminished fifth above the finalis, making it rare in tonal music. Both modes are identified by their interval patterns and characteristic pitches in performed or notated passages.
- Aeolian: Equivalent to natural minor: W-H-W-W-H-W-W. The most common minor-quality mode in tonal music.
- Locrian: Built on scale degree 7 of the major scale: H-W-W-H-W-W-W. Characterized by a diminished fifth (b5) above the finalis, creating strong instability.
- Modal center (finalis): The pitch that functions as the tonal home base of a modal melody, analogous to the tonic in major or minor.
Given a notated melody with a key signature, identify whether it is Aeolian or Locrian by locating the finalis and checking the interval above it.
| Mode | Built on Scale Degree | Key Characteristic | Stability |
|---|
| Aeolian | 6th | Natural minor equivalent | Stable |
| Locrian | 7th | Diminished fifth above finalis | Unstable |