Ab 9sus4 (Ab9sus4)
Also written as G# 9sus4 (G# and Ab are the same key).
Notes in Ab 9sus4
Inversions
Same notes as Ab 9sus4, with a different chord tone as the lowest note. Useful for smoother movement between chords instead of jumping around the keyboard.
Root position
G# in the bass
1st inversion
C# in the bass
2nd inversion
D# in the bass
3rd inversion
F# in the bass
4th inversion
A# in the bass
Open voicings
A close-position chord like Ab 9sus4 can sound cluttered in the middle of the keyboard. Jazz players open it up by dropping one note down an octave, spreading the same notes wider without changing the chord.
Drop 2
F# on the bottom
Drop 3
D# on the bottom
The notes G#, C#, D#, F# and A# make up Ab 9sus4.
A 7sus4 chord with a ninth added on top. The suspended fourth keeps the chord open and undecided between major and minor, while the ninth fills out the top end. Gospel and modern jazz piano lean on it for vamps that need movement without committing to either quality.