Diminished octave
| Inverse | Augmented unison |
|---|---|
| Name | |
| Other names | Diminished eighth |
| Abbreviation | d8 |
| Size | |
| Semitones | 11 |
| Interval class | 1 |
| Just interval | 48:25 |
| Cents | |
| Equal temperament | 1100 |
| 24 equal temperament | 1100 |
| Just intonation | 1129 |
In classical music from Western culture, a diminished octave (
Play ) is an interval produced by narrowing a perfect octave by a chromatic semitone. As such, the two notes are denoted by the same letter but have different accidentals. For instance, the interval from C4 to C5 is a perfect octave, twelve semitones wide, and both the intervals from C♯4 to C5, and from C4 to C♭5 are diminished octaves, spanning eleven semitones. Being diminished, it is considered a dissonant interval.
The diminished octave is enharmonically equivalent to the major seventh.
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