The third voice from the top lowered an octave. The dropped voice becomes the bass, which is why a string is skipped.
Abaug7 is Ab, C, E and Gb — Ab7 with the fifth raised a semitone.
It sounds strained and chromatic. The raised fifth is heard as a ♭13 sitting a semitone above where it is going, so the chord pushes harder than a plain dominant.

| Ab | C | E | Gb |
|---|---|---|---|
| 1 | 3 | ♯5 | ♭7 |
Altered dominant — the pull of a 7, sharpened.
Also written Ab7#5, Ab+7 or Ab7(#5). The same chord either way; which spelling you meet depends on who wrote the chart.
The same operation one voice further down: the third voice from the top falls an octave and becomes the bass.
That leaves a bigger hole under the top three notes, so a string gets skipped: the muted string in the middle is the shape, not a mistake.
Abaug7 has 9 of them, on strings 5-3-2-1 and strings 6-4-3-2, from open position up to the 13th — every inversion the chord has: Ab in the bass, C in the bass, E in the bass and Gb in the bass. The one to learn first is the C shape at the nut.
5 of them sit on strings 6-4-3-2, so you can run the inversions up one set without changing strings — which is the whole reason to learn them as a family rather than as separate grips.
Start with 434x5x — low, at the 3rd fret. 1 of the 6 shapes here sits in open position. None of them needs a barre. Together they cover the neck from the 3rd fret to the 14th.
| Frets | Where | Bass | Top | Hand |
|---|---|---|---|---|
| 4x4550 | open position | Ab, root position | E | 1 open string |
| 434x5x | 3rd fret | Ab, root position | E | all fretted |
| xx6978 | 6th fret | Ab, root position | C | all fretted |
| x-11-10-11-9-0 | 9th fret | Ab, root position | Ab | 1 open string |
| x-11-10-11-x-12 | 10th fret | Ab, root position | E | all fretted |
| x-11-14-11-13-12 | 11th fret | Ab, root position | E | all fretted |
The same notes rebuilt from scratch give 2 shell, 14 drop 2 and 6 open string voicings, each on its own page.
Tensions. A shell of Abaug7, root, third and seventh, leaves a string free, and the tones that belong over it are the b9 (Bbb), the 9 (Bb), the #9 (B) and the #11 (D).
Abaug7 is a dominant with its tension raised, so it still points at Db — harder than a plain seventh does, because the altered tones sit a semitone from where they are going.
Every note of Abaug7 is in Ab whole tone and Ab altered.
Change one note of Abaug7 and you have Abmaj7#5 (the flat seventh becomes a major seventh), Ab7 (the sharp fifth becomes a fifth), Ab7b5 (the sharp fifth becomes a flat fifth), Abalt (add the flat ninth), Abaug (drop the flat seventh) or Abaug9 (add the ninth).
Abaug7 is an altered chord — a dominant seventh with its fifth or ninth moved. Altered dominant chords on every root.
On Abaug7’s sound and use this page follows Mark Levine, The Jazz Theory Book (Sher Music, 1995). The shapes and the derived voicings come from different places, and both are explained in where the chords and the theory come from.
Shows each chord the way this style would voice it, and marks which of its alternatives belong to the idiom.