Since there are only seven degrees in a
diatonic scalethe eleventh degree is the same as the subdominantand the interval of an eleventh is a compound fourth.
An eleventh chord is a chord which contains the tertian extension of the eleventh. Typically found in
jazz, an eleventh chord will also usually include the seventh and ninth along with elements of the basic triad structure. However, since the major diatonic eleventh (for example the F on the C11 chord shown at right) would create a dissonant minor ninthinterval with the third of the chord (the E), it is not used in functional contexts. The dominant eleventh (C, E, G, B♭, D, F), for example, usually omits the fifth and third Audio|Dominant eleventh chord on C.mid|play. The dominant 7#11 chord usually omits the fifth since the sharpened eleventh equals the lowered fifth (b5) Audio|Db7sharp11 chord.mid|Play.
In the dominant eleventh, because this minor ninth interval between the third and the eleventh is more problematic to the ear and to
voice leadingthan a major ninth would be, alterations to the third or eleventh scale degrees are a common solution. When the third is lowered, a minor eleventh chord is formed with a major ninth interval between the two notes in question (e.g. C, E♭, G, B♭, D, F) Audio|Minor eleventh chord on C.mid|play. Similarly, the eleventh may be raised chromatically over a major triad (e.g. to F♯ in a C major chord) to imply the lydian dominant mode. A less common solution to the issue is to simply omit the third in the presence of the eleventh, resulting in a chord enharmonic to the suspended chord(sus4). This type of chord should be notated as such.
The eleventh chord, with the third omitted and the seventh flattened, is particularly useful in
diatonicmusic when a composer or accompanist wishes to allow the tonicnote of a key to be heard while also sounding the dominantof that key in the bass, but while not playing the second inversion of the triad on the tonic. Therefore, something similar to a perfect cadencemay be attempted under a melody which does not leave the tonic note (e.g. a perfect cadence in F might require that the melody moves by step from E to F, or from G to F; whereas, if the first of the two notes is harmonized by an eleventh chord, the melody may remain on F, while the bass still plays the typical pattern of a perfect cadence i.e. dominant-tonic). The eleventh chord also expands the versatility of the dominant pedalcompositional technique.
Elektra chord, analyzible as an E11
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