Extended chord
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In music, extended chords are tertian chords (built from thirds) or triads with notes extended, or added, beyond the fifth, including all the thirds in between the fifth and the furthest extended note. Thus, seventh, ninth, eleventh and thirteenth chords are extended chords. The thirteenth is the furthest extension diatonically possible as, by that point, all seven tonal degrees are represented within the chord.
In practice however, extended chords do not typically use all the chord members; when it is not altered, the fifth is often omitted, as are notes between the seventh and the highest note (i.e., the ninth is often omitted in an eleventh chord; the ninth and eleventh are usually omitted in a thirteenth chord).
Chords extended beyond the seventh are rarely seen in the Baroque era, and are uncommon in the Classical era. When used in the Romantic era, they were almost always found on the dominant scale degree (as V9, V11, and V13).
Performance
When playing extended chords on instruments which are limited to four or fewer tones, it is important to select which notes to play so as to still give the sonority or effect as the intended extended chord. Priority should be given to the third, seventh and the most extended note, as these indicate the quality of the chord. Adding the root is also important though the root may be indicated by the chosen notes and musical context or may be passed to a bass instrument. The third defines the chord's quality as minor or major, the extended note is what makes the chord extended, and the seventh defines the chord as an extended chord and not an added note chord. Any notes which happen to be altered, such as a flatted fifth or ninth, should also be given priority. Thus in a thirteenth chord one would play the root, third, seventh, and thirteenth, and be able to leave out the fifth, ninth, and eleventh.
As the sonority of an extended chord may be compromised if it is played on an instrument with a narrow tonal range, it is recommended that such chords be played over a wide range, on a keyboard instrument or by a whole ensemble. The best sound can be achieved by dispersing the degrees of the chord in such fashion that the minimum distance between adjacent tones will be a fourth. If a keyboard instrument is used, both hands will be needed for playing the chords.
Further reading
- Popp, Marius (1998). Applicatory Harmony in Jazz, Pop & Rock Improvisation. ISBN 9735692287.