Augmented octave

Augmented octave
Inversesee "Augmented unison"
Name
Other namesAugmented eighth
AbbreviationA8
Size
Semitones13
Interval class1
Just interval25:12
Cents
12-Tone equal temperament1300
Just intonation1271
Augmented octave on C. Play

In 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]

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