Half-diminished seventh chord

Not to be confused with Diminished seventh chord.
See also: Dominant seventh flat five chord
half-diminished seventh chord
Component intervals from root
minor seventh
diminished fifth (tritone)
minor third
root
Tuning
5:6:7:9[1] or 25:30:36:45[2]
Forte no. / Complement
4-27 / 8-27

In music theory, the half-diminished seventh chord (also known as a half-diminished chord or a minor seventh flat five chord) is a seventh chord composed of a root note, together with a minor third, a diminished fifth, and a minor seventh (1, ♭3, ♭5, ♭7). For example, the half-diminished seventh chord built on B, commonly written as Bm7(♭5), or Bø7, has pitches B-D-F-A:

{ \omit Score.TimeSignature \relative c' { <b d f a>1 } }

It can be represented by the integer notation {0, 3, 6, 10}.

The half-diminished seventh chord exists in root position and in three inversions. The first inversion is enharmonic to a minor sixth chord:

Half-diminished chord inversions
Half-diminished chord inversions

In diatonic harmony, the half-diminished seventh chord occurs naturally on the seventh scale degree of any major scale (for example, Bø7 in C major) and is thus a leading-tone seventh chord in the major mode.[3] Similarly, the chord also occurs on the second degree of any natural minor scale (e.g., Dø7 in C minor). It has been described as a "considerable instability".[4]

  1. ^ Fétis, François-Joseph and Arlin, Mary I. (1994). Esquisse de l'histoire de l'harmonie, p. 139n9. ISBN 9780945193517.
  2. ^ Shirlaw, Matthew (2012). The Theory of Harmony, p. 86. ISBN 9781451015348.
  3. ^ Benward & Saker (2003). Music: In Theory and Practice, Vol. I, p. 217. ISBN 978-0-07-294262-0.
  4. ^ Henry, Earl and Rogers, Michael (2004). Tonality and Design in Music Theory, Vol. I, p. 295. ISBN 0130811289.