{{short description|Musical interval of ten diatonic steps}} {{Infobox musical interval| main_interval_name = perfect eleventh| inverse = perfect fifth| other_names = Compound fourth| abbreviation = P11| semitones = 17| interval_class = 1| just_interval = 8:3| cents_equal_temperament = 1700.0| cents_24T_equal_temperament = | cents_just_intonation = 1698.0 }} thumb|Augmented eleventh on C. {{Audio|Augmented eleventh on C.mid|Play}}|175x175px {{Infobox musical interval| main_interval_name = augmented eleventh| inverse = diminished fifth| other_names = | abbreviation = A11| semitones = 18| interval_class = 6| just_interval = 45:16| cents_equal_temperament = 1800.0| cents_24T_equal_temperament = | cents_just_intonation = 1790.2 }} In music theory, an '''eleventh''' is a compound interval consisting of an octave plus a fourth. A perfect eleventh spans 17 and the augmented eleventh 18 semitones, or 10 steps in a diatonic scale. For instance, the interval between C<sub>4</sub> and F<sub>5</sub> (in scientific pitch notation) is a perfect eleventh. :<score sound> { \override Score.TimeSignature #'stencil = ##f \relative c' { \time 4/4 \set Score.tempoHideNote = ##t \tempo 1 = 20 <c f'>1 } } </score>

Since there are only seven degrees in a diatonic scale, the eleventh degree is the same as the subdominant (IV).<ref>{{cite book|last1=Benward|first1=Bruce|last2=Saker|first2=Marilyn|title=Music: In Theory and Practice, Vol. I|publisher=McGraw-Hill Education|date=2003|isbn=978-0-07-294262-0}}</ref>

An eleventh chord is the stacking of five thirds in the span of an eleventh. In common practice tonality, it usually had subdominant function as minor eleventh chord on the second degree (supertonic) of the major scale.

The quarter tone scale offers an alternative eleventh of 1650 cents, which is very close to the just interval 11:4, the undecimal eleventh (1651.3 cents).

==See also== *Eleventh chord *Extended chord

==References== {{reflist}}

{{Intervals}} {{Chord factors}}

Category:Chord factors Category:Fourths (music) Category:Compound intervals

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