music_theory:extended_tertian_harmony [Bondari Wiki]

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====== Extended Tertian Harmony: 9th, 11th, and 13th Chords ======

> **Concept:** By adding additional thirds to //triadic// harmony, one can create 9<sup>th</sup>, 11<sup>th</sup>, and 13<sup>th</sup> chords.

//Note:// It is common - and often necessary - to omit some notes of the chord, especially in four-part writing.

Examples:

{{music_theory:extended_tertian_harmony_-_common_constructions.png?800|}}

Function: Most 9<sup>th</sup>, 11<sup>th</sup>, and 13<sup>th</sup> chords are dominant chords (V<sup>9</sup>, V<sup>11</sup>, V<sup>13</sup>), though in reality any triad can be extended. Other common non-dominant extended tertian chords are based on I and IV. Stacking extra thirds onto a triad does NOT change its original function! For instance, a V<sup>11</sup> chord still typically resolves to I (or i), and a ii<sup>9</sup> chord still typically resolves to dominant harmony (V).

Position: Extended tertian chords are usually found in root position, as they tend to lose their identity when inverted. Secondary function: 9<sup>th</sup>, 11<sup>th</sup>, and 13<sup>th</sup> chords can also occur as [[secondary dominants]].

Analyze this progression:

{{ :music_theory:extended_tertian_harmony_-_secondary_dominant_example.png?700 }}

{{ :music_theory:extended-tertian-harmony-example.mp3 | :music_theory:extended-tertian-harmony-example.ogg }}

===== Summary =====

^ Chord  ^ Typical Members Present  ^ Voice-Leading Guides  ^
| V<sup>9</sup>  | R, 3, 7, 9  | 9<sup>th</sup> and 7<sup>th</sup> resolve downward to the 5th and 3rd of the tonic triad.  |
| V<sup>11</sup>  | R, 3, 7, (9), 11  | 11<sup>th</sup> is retained as a common tone with the tonic triad.  |
| V<sup>13</sup>  | R, 3, 7, (9), 13  | 13<sup>th</sup> is usually in the highest voice and resolves downward to the tonic.\\ If the tonic triad contains a chordal 9<sup>th</sup>, the 13<sup>th</sup> could resolve downward to the 9<sup>th</sup> of I<sup>9</sup>.  |