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    YoutubeMusic Theory Video SeriesA step-by-step guide to music theory fundamentals. These 60-second videos provide a clear, structured path to understanding how music works, optimized for a full-screen learning experience.YoutubeMusic Theory ShortsMaster music theory concepts in 60 seconds or less. Quick, vertical videos designed to give you essential theory knowledge in a fast-paced, mobile-friendly format.
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    1. Home
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    5. C
    7. Diminished octave

    Diminished octave

    The distance spanning eight note names, returning to the same note name one octave higher, with 11 semitones between them.

    d811 semitones

    Guitar diagrams

    Sheet music

    Which chords use the Diminished octave interval?

    Chords whose formulas include this interval from the root note.

    Which scales use the Diminished octave interval?

    Scales whose formulas include this interval.

    Similar intervals

    Intervals with a comparable quality and character.

    Practice the Diminished octave interval

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    Learn music theory with sonid

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    Practice the Diminished octave interval

    Open the app and start your daily workout!

    Learn music theory with sonid

    Available on Android and iOS

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    The diminished octave (d8) spans 11 semitones. It is an octave contracted by a semitone and is enharmonically close to a major seventh in equal temperament, but functionally distinct in notation.

    Construction and spelling

    d8 is formed by lowering a perfect octave by one semitone, such as C-Cb. Though it may sound like M7 in equal temperament, the spelling signals octave-family contraction, not seventh expansion. This distinction matters in advanced theory.

    Harmonic and melodic usage

    Harmonically, d8 appears mainly in chromatic contexts, voice-leading analysis, and enharmonic reinterpretation. Melodically, it marks unusual contour and tension. Its primary value is precise functional spelling.

    Examples

    • Chromatic notation where octave relation is preserved
    • Enharmonic respellings in modulation analysis
    • Theoretical comparisons between d8 and M7 spellings

    In practice

    Practice d8 by contrasting C-Cb with C-B to separate notation from pitch equivalence. Read and sing with clear accidentals to internalize functional intent. This improves advanced notation literacy.

    Diminished fourth
    Diminished fifth
    Diminished octave
    Diminished duodecime