Half diminished scale

The half diminished scale is a seven-note musical scale. It is more commonly known as the Locrian ♯2 scale^[1] or the Aeolian ♭5 scale, names that avoid confusion with the diminished scale and the half-diminished seventh chord (minor seventh, diminished fifth). It is the sixth mode of the ascending melodic minor scale.

Half diminished scale

Modes	I, II, III, IV, V, VI, VII
Component pitches
C, D, E♭, F, G♭, A♭, B♭
Qualities
Number of pitch classes	7
Forte number	7-34
Complement	5-34

In the key of B♭, the half-diminished scale built on C is associated with Cm^7♭5, which functions as a ii^ø7 chord in minor (see chord-scale system).