Eleventh Chord - Fourth

The fourth factor of a chord is the note or pitch four scale degrees above the root or tonal center. When the fourth is the bass note, or lowest note, of the expressed chord, the chord is in first inversion Play. However, this is equivalent to a gapped ninth chord.

Conventionally, the fourth is third in importance to the root, fifth, and third, being an added tone. It may be avoided as the root since that inversion may resembles a ninth chord on the fourth rather than a suspended chord on the original note. In jazz chords and theory, the fourth is required due to its being an added tone.

The quality of the fourth may be determined by the scale or may be indicated. For example, in both a major and minor scale a diatonic fourth added to the tonic chord will be major (C-F-G) while one added to the subdominant chord will be major or minor (F-B-C or F-B♭-C), respectively.

The fourth is octave equivalent to the eleventh. If one could cut out the note in between the fifth and the eleventh and then drop the eleventh down an octave to a fourth, one would have a fourth chord (CEGB♭D'F' – B♭D' = CEFG). The difference between sus4 and add11 is conventionally the absence or presence, respectively, of the third.