Upright Bass: Ab Whole Half Diminished Over the Changes

Ab Whole Half Diminished runs 8 notes to the octave, laid out here on EADG with every Ab flagged. Mid-chorus the pattern is not what you need; where the root is when the chord changes underneath you is.

Unstable and eerie — alternating whole and half steps, with the b3, b5, and 6 spelling a diminished seventh chord in every direction. Ominous, symmetrical, and unresolved.

Heard in: Diminished seventh chords in classical and jazz, horror and suspense scores, Bartok and Stravinsky, and neoclassical metal.

The upright takes a chorus less often than anyone, and that is exactly why these matter: the notes between one chord root and the next come out of a scale, and a walk that lands on the wrong one is the loudest wrong note in the room.

Play it slowly against the audio until it stops being a shape, then put it over two bars of a form and let the chord tones decide which of the notes you actually keep.