Inverse see "Augmented unison" Abbreviation A8 Interval class 1 | Other names Augmented eighth Semitones 13 Just interval 25:12 | |
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In modern Western tonal music theory an augmented octave is the sum of a perfect octave and an augmented unison or chromatic semitone. It is the interval between two notes, with the same note letter on staff positions an octave apart, whose alterations cause them, in ordinary equal temperament, to be thirteen semitones apart. In other words, it is a perfect octave which has been widened by a half-step, such as B♭ and B♮ or C and C♯; it is a compound augmented unison. It is the enharmonic equivalent of a minor ninth.
References
Augmented octave Wikipedia(Text) CC BY-SA