Other Tertian Chords (Extended Chords)

1. The 9th Chord (Ninth)

The Ninth Chord is built by stacking 5 notes in thirds from the root (1 - 3 - 5 - 7 - 9). By adding the 9th, it injects a lush, floating, and nostalgic color to the harmony, expanding the expressive palette beyond seventh chords.

It is widely used in Jazz, R&B, and sophisticated pop arrangements.

2. The 11th Chord (Eleventh)

The Eleventh Chord is built by stacking 6 notes in thirds (1 - 3 - 5 - 7 - 9 - 11). It is most frequently used as a minor 11th chord (m11), because the minor 3rd prevents the harsh tritone clash with the perfect 11th.

It has a highly modern, suspended, and atmospheric quality, popular in modal jazz and film scores.

3. The 13th Chord (Thirteenth)

The Thirteenth Chord represents the dense limit of tertian stacking, containing 7 notes in thirds (1 - 3 - 5 - 7 - 9 - 11 - 13). This chord effectively spans every single note of the diatonic scale in a single stacked structure!

It produces an exceptionally rich, full, and complex harmonic color, providing the ultimate voice leading opportunities.

Extended Expressivity (9ths, 11ths & 13ths)

Extending tertian stacking beyond the octave unlocks lush harmonic colors, impressionist atmospheres, and sophisticated voicings essential to modern jazz, film scoring, and contemporary pop.