Audio: add chord (0:08)
add chord sings add chords a capella in the key of C. The add chord figure shows the score:
An add chord or added tone chord is a four note chord constructed by adding an extra note to a triad.
The three types of add chord are add2, add4 and add6 or major sixth chord. They are notated by adding the number 2, 4 or 6 representing the interval of second, fourth and sixth above the root respectively. There is no add7 chord, or rather there is, but it is called a seventh chord and occupies an elevated position in the chord zoo.
Add chords derive their name from functional harmony. The added note is treated as an embellishment. In add2 and add4 chords the function of the added note is a passing note, in the major sixth chord the added note is a neighbour note.
The dominant seventh sharp ninth chord (7#9) can be considered an add chord. At a stretch that is. In this case a minor third is added to a major triad. More commonly, a minor third is added to a dominant seventh chord. The added minor third is notated as an augmented second and shifted up an octave to make it an interval of an augmented ninth, #9.
Add chords work with a minor scale as well as a major scale. Altering triads to form major and minor add chords and sixth chords is a simple and effective way to change the timbre of a harmony.
Probably the only thing to watch out for in an add chord is a tritone. For example, Fadd4 contains the notes FABC and there is a tritone, FB, between the root and the fourth. Add chords can be altered to get rid of the tritone, as in bar 3 of add chord, where Fadd4 has been modified to FABbC so there is a perfect fourth above the root, FBb, instead of a tritone.
An add chord is a good example of the problem of chord notation. Take the four note chord CEGA as an example. This is a C6 chord. Move the last note to the beginning to make the chord ACEG. This is an A minor seventh chord, Am7. C6 and Am7 contain exactly the same notes. In functional harmony, chords containing the same notes have different functions. The function of any chord is that of the underlying triad. C6 functions as a C triad and Am7 as an A minor triad. In pop harmony the two chords are equivalent nonfunctional chords and can be used and notated interchangeably. A common feature of all chords with four or more notes is that they can be notated and interpreted in different ways.