Augmented seventh Augmented seventh In classical music from Western culture, an augmented seventh is an interval produced by widening a major seventh by a chromatic semitone. For instance, the interval from C to B is a major seventh, eleven semitones wide, and both the intervals from C to B, and from C to B are augmented sevenths, spanning twelve semitones. Being augmented, it is classified as a dissonant interval. However, it is enharmonically equivalent to the perfect octave. Since an octave can be described as a major seventh augmented by a diatonic semitone, the augmented seventh is the sum of an octave,
Eleventh Eleventh In music or music theory an eleventh is the note eleven scale degrees from the root of a chord and also the interval between the root and the eleventh. The interval can be also described as a compound fourth, spanning an octave plus a fourth. Since there are only seven degrees in a diatonic scale the eleventh degree is the same as the subdominant. The eleventh is considered highly dissonant with the third. A perfect eleventh is an eleventh which spans exactly 17 semitones. It can be also described as a compound perfect fourth, spanning an octave plus a