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Extended chords add ninths, elevenths, and thirteenths to seventh chords, creating richer color but adding dissonance. Voice leading extended chords requires careful management of which chord members appear in which voice and how extensions resolve. Commonly, extensions resolve downward by step, and the voicing omits or compresses certain chord members to accommodate upper extensions. Upper extensions appear frequently in jazz and contemporary classical music, where their voice leading differs from traditional common practice conventions.
Analyze jazz lead sheets and standards that use Cmaj9, Cmin11, and Cdom13 chords. Notice which tones are voiced and which omitted, then experiment with voicing the same chord in different ways to hear the different colors.
From your work on extended chords you know what these sonorities are theoretically: a seventh chord with additional thirds stacked above it, producing the ninth (two octaves above the second), the eleventh (two octaves above the fourth), and the thirteenth (two octaves above the sixth). In theory, a complete thirteenth chord has seven distinct pitch classes. In practice, you almost never voice all seven simultaneously — the result would be acoustically thick to the point of muddiness. The craft of voicing extended chords is selecting which notes to include, which to omit, and how to arrange them in register so the distinctive color of the extension comes through clearly.
The essential tones in any extended dominant chord are the third and seventh, because they form the tritone that defines the chord's function and drives the resolution you learned about in seventh-chord work. These tones are almost never omitted. The fifth is typically the first candidate for omission because it adds little color — a perfect fifth creates no tension and crowds the voicing without contributing anything distinctive. The root can sometimes be omitted entirely in a chord voicing when the bass player is supplying it, which frees up space in the middle register for extensions. The result is what jazz pianists call a shell voicing: third and seventh in the middle, extension on top, root in the bass (often played by a bassist rather than the pianist).
Upper extensions resolve characteristically. The ninth behaves like a suspended second: it gravitates downward toward the root, or it can be held as a stable color tone over a non-dominant chord (major ninth chords are stable, not tense). The eleventh on a dominant or major chord creates a potential clash: the natural eleventh is a perfect fourth above the root, which sounds directly against the major third. The solution is the raised eleventh (augmented fourth above the root), which avoids the clash and produces a bright, Lydian color. The thirteenth behaves like a sixth — it typically appears as the highest voice in the chord, adding brightness and a characteristic wide-open sonority.
In jazz voicing, extended chords are often spread across registers in ways that place the extensions in the interior rather than stacked on top. A guitarist or pianist voicing a Cmaj9 might put the root in the bass, the seventh and third close together in the middle, and the ninth just above them — creating a dense, lush cluster of fourths and seconds that is the signature sound of jazz harmony. The voicing makes the extension audible not by piling every note on top in ascending thirds (the theoretical stack) but by placing tones where they create the richest interaction among neighbors. Experimenting with the same chord in multiple voicings — same notes, different arrangement — reveals how dramatically register and spacing change the chord's perceived color and character.
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