A Locrian 𝄫3 ♭4 Scale
A Locrian 𝄫3 ♭4 contains 7 notes: A, B♭, C♭, D♭, E♭, F, G. It has 4 flats: B♭, C♭, D♭, E♭. The step pattern is H–H–W–W–W–W–W.
The most altered mode of the Neapolitan major family, with almost every degree flattened and the 3rd double-flatted. It exists at the theoretical extreme of modal alteration.
The formula is 1, b2, bb3, b4, b5, b6, b7. The bb3 is enharmonically a major 2nd, creating a paradoxical interval: what sounds like a whole step is notated as a diminished 3rd. Understanding these enharmonic relationships deepens one's grasp of how modal theory works at its edges.
Purely theoretical. If encountered, treat it as a brief chromatic color resolving quickly to something stable. Its value is in understanding the complete modal system of the Neapolitan major scale.