Another sound which is related to suspended chords is the addition of the ninth degree to either a major or minor triad. This creates an add9 chord when applied to a major triad, or a minor add9 chord when applied to a minor triad. The ninth degree of a scale is a duplication of the second degree an octave higher. However, when using the 9th degree, it may appear in any octave and may be played by either hand. Chords extending past the octave will be dealt with in more detail in the following lesson. Here is an example which demonstrates both major and minor add9 chords.
Here is a piano part which uses both suspended and add9 chords. Bar 4 features an Ab sus2 chord, in which the added 9th (2nd) replaces the 3rd of the chord