AKA: C9 sus4, C ninth suspended fourth, C9sus, C nine suspended, C Dominant ninth suspended 4
C9sus4 Chord on Accordion
9sus4 Chords
These chords can add a sense of tension and resolution to a musical phrase and are often used to create movement and interest in a chord progression. Sus4 chords are chords that are built by replacing the 3rd note of the scale with the 4th note. A 9sus4 chord is a type of suspended chord that is built by adding the 7th and the 9th notes of the scale to a sus4 chord.
For example, in the key of C, a Csus4 chord would consist of the notes C, F, and G, with the F replacing the E that would be in a standard C major chord. A 9sus4 chord would add the Bb (7th) and the D (9th) to the Csus4 chord, resulting in the notes C, F, G, Bb, and D, which are root, perfect 4th, perfect 5th, minor 7th and major 9th intervals.
C9sus4: In-depth analysis
For a more in-depth grasp of the C9sus4 chord, delve into my article titled “C9sus4 Piano Chord – Charts, Harmony, and Music Theory” on ChordsAround.com
9sus4 Chords on Accordion
On a standard bass accordion, 9sus4 chords are actually 9sus4(5omit) because no button combination allows for the creation of a complete 9sus4 chord that includes the 5th (which btw doesn’t add any tension to the chord). This chord is the best option available on the Stradella system to play a suspended chord.
A 9sus4(5omit) chord can be created by combining a root note with the Major chord built on its minor 7th interval.
For example, combining the root note C with the Bb Major chord (since Bb is at a minor 7th interval from C) results in a C9sus4(5omit) chord, which is formed by the notes C, F, Bb, and D (root, perfect 4th, minor 7th, and 9th). To simplify the nomenclature, we avoid mentioning the missing 5th every time we mention this chord, just remember it.
It’s very similar to a ninth eleventh chord but it does not have either the 3rd or the 5th and the 11th is seen as a 4th.
Notes:
C, F, Bb, D
Intervals:
R, 4°, m7°, 9°
Left hand:
C + B♭M
Fingering:
2 + 4
or
3 + 5