Augmented octave

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Augmented octave
Inverse see "Augmented unison"
Other names Augmented eighth
Abbreviation A8
Semitones 13
Interval class 1
Just interval 25:12
Equal temperament 1300
Just intonation 1271
Augmented octave on C. About this sound Play 

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.[1]

See also[edit]


  1. ^ William Drabkin, "Octave (i)", in Grove Music Online. Oxford Music Online. Accessed February 2012. (subscription needed)