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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
    3. Interval Library
    5. C
    7. Augmented octave

    Augmented octave

    The distance spanning eight note names, returning to the same note name one octave higher, with 13 semitones between them.

    A813 semitones

    Guitar diagrams

    Sheet music

    Which chords use the Augmented octave interval?

    Chords whose formulas include this interval from the root note.

    Which scales use the Augmented octave interval?

    Scales whose formulas include this interval.

    Similar intervals

    Intervals with a comparable quality and character.

    Practice the Augmented octave interval

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    Learn music theory with sonid

    Available on Android and iOS

    Practice the Augmented 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 augmented octave (A8) spans 13 semitones. It is an octave widened by a semitone and is enharmonically close to m9 in equal temperament, but notationally distinct.

    Construction and spelling

    A8 is formed by raising a perfect octave by one semitone, such as C-C#. Though it may sound like m9, the spelling preserves octave-family expansion. This distinction matters in advanced analysis.

    Harmonic and melodic usage

    Harmonically, A8 appears mostly in chromatic notation, enharmonic reinterpretation, and theoretical contexts. Melodically, it creates pointed, unusual contour. Its main value is functional spelling clarity.

    Examples

    • Chromatic passages where octave relation is explicit
    • Enharmonic respellings in modulation analysis
    • Theoretical comparison of A8 and m9 spellings

    In practice

    Practice A8 against m9 to separate pitch equivalence from notation function. Read accidentals carefully and track interval names as part of analysis. This strengthens high-level interval literacy.

    Augmented unison
    Augmented fourth
    Augmented fifth
    Augmented octave
    Augmented undecime