C 9sus4 (C9sus4)
Notes in C 9sus4
Inversions
Same notes as C 9sus4, with a different chord tone as the lowest note. Useful for smoother movement between chords instead of jumping around the keyboard.
Root position
C in the bass
1st inversion
F in the bass
2nd inversion
G in the bass
3rd inversion
Bb in the bass
4th inversion
D in the bass
Open voicings
A close-position chord like C 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
Bb on the bottom
Drop 3
G on the bottom
Play C, F, G, Bb and D together and you get C 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.