The Half Diminished Chord: A Complete Guide for Musicians

What is a Half Diminished Chord?

A half diminished chord, also known as a minor seventh flat five (m7♭5), is a four-note chord consisting of:

• Root
• Minor third
• Diminished fifth
• Minor seventh

The chord formula is: 1 - ♭3 - ♭5 - ♭7

Historical Context and Musical Significance

Emerging in the Romantic era, half diminished chords became crucial in:

• Classical music as predominant chords
• Jazz standards as iiØ7 chords in minor keys
• Film scoring for mysterious/dramatic effects

Technical Construction

Interval Structure

• Root to ♭3: Minor 3rd (3 semitones)
• ♭3 to ♭5: Minor 3rd (3 semitones)
• ♭5 to ♭7: Major 3rd (4 semitones)

Common Voicings

Piano: BØ7 = B-D-F-A (closed position)

Guitar: X2323X (BØ7 in drop 2 voicing)

Practical Applications

In Jazz

As the ii chord in minor ii-V-i progressions:

BØ7 - E7 - Am7

In Classical Music

As predominant harmony leading to dominant:

ii× - V7 - I

Progressive Exercises

Level 1: Identification

Play CØ7 (C-E♭-G♭-B♭) in all inversions

Level 2: Progressions

Practice ii×-V7-I in all minor keys

Level 3: Substitutions

Replace dominant chords with ×9 chords

Genre Applications

Jazz

Used extensively in standards like "Autumn Leaves"

Rock/Pop

Creates tension in progressions (e.g., Radiohead)

Classical

Essential in Romantic era chromatic harmony