As an eleventh ( from Lat undecimus: " the eleventh " ) is called in music an interval, which is composed of an octave and fourth and so eleven scale degrees of a diatonic, heptatonic scale spans (eg c -f1 ). The frequency ratio between the fundamental and its pure eleventh is 8 /3 System.
Note Example: Undezimintervalle
The (pure ) eleventh (a) comprises seventeen semitones. In counterpoint and harmonic set Undezimen are usually as fourths to treat. In the jazz harmonies of the eleventh falls as the fifth third above the tonic ( b ) have a special role and is valued in the chord symbols with "11".
Related to the partials series, such as organ stops, the 11 partial tone is referred to as the eleventh. This eleventh to the next lower octave has a frequency ratio of 11:8.