In medieval and modern music, the Locrian mode is a diatonic (seven-note) scale or musical mode which corresponds to the white keys of the piano from B to B. It may be considered an “excerpt” of a major scale played from the pitch a semitone below the major scale's tonic, i.e., a major scale played from its leading tone up to its leading tone again. The resulting scale is minor, because as the B becomes the new tonal centre the minor third between the B and the D makes us “hear minor”.
The Locrian mode is the only modern diatonic mode in which the tonic chord is a diminished chord, resulting in a tonic chord that is considered dissonant. For example, the tonic chord of B Locrian is made from the notes B, D, F. The interval between the tonic (B) and the dominant (F) is a diminished fifth or tritone.
In modern practice, the Locrian may be considered to be a natural minor (Aeolian) scale with the second and fifth scale degrees lowered by a semitone.
It is difficult to write pure Locrian-mode passages that are unambiguously in the Locrian mode, so the actual mode of these passages may be more open to interpretation in a different mode than is usual for passages in other modes that more closely resemble a major or minor scale.
Among the few compositions that consistently use Locrian mode we can count:
- The march from “Three Fantastic Dances” by Dmitri Shostakovich
- Jeux by Claude Debussy
- The opera Death in Venice by Benjamin Britten
Two-octave Locrian scales are also available: PDF