| Inverse | perfect fifth |
|---|---|
| Name | |
| Other names | Compound fourth |
| Abbreviation | P11 |
| Size | |
| Semitones | 17 |
| Interval class | 1 |
| Just interval | 8:3 |
| Cents | |
| 12-Tone equal temperament | 1700.0 |
| Just intonation | 1698.0 |
| Inverse | diminished fifth |
|---|---|
| Name | |
| Abbreviation | A11 |
| Size | |
| Semitones | 18 |
| Interval class | 6 |
| Just interval | 45:16 |
| Cents | |
| 12-Tone equal temperament | 1800.0 |
| 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 C4 and F5 (in scientific pitch notation) is a perfect eleventh.
Since there are only seven degrees in a diatonic scale, the eleventh degree is the same as the subdominant (IV). [1]
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).
