In Western
tonal music theory
Music theory is the study of the practices and possibilities of music. ''The Oxford Companion to Music'' describes three interrelated uses of the term "music theory". The first is the "rudiments", that are needed to understand music notation (ke ...
, an augmented octave is the sum of a perfect
octave
In music, an octave ( la, octavus: eighth) or perfect octave (sometimes called the diapason) is the interval between one musical pitch and another with double its frequency. The octave relationship is a natural phenomenon that has been refer ...
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
An equal temperament is a musical temperament or tuning system, which approximates just intervals by dividing an octave (or other interval) into equal steps. This means the ratio of the frequencies of any adjacent pair of notes is the same, wh ...
, to be thirteen
semitones apart. In other words, it is a perfect
octave
In music, an octave ( la, octavus: eighth) or perfect octave (sometimes called the diapason) is the interval between one musical pitch and another with double its frequency. The octave relationship is a natural phenomenon that has been refer ...
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
In modern musical notation and tuning, an enharmonic equivalent is a note, interval, or key signature that is equivalent to some other note, interval, or key signature but "spelled", or named differently. The enharmonic spelling of a written n ...
equivalent of a
minor ninth.
[
]
See also
* False relation
A false relation (also known as cross-relation, non-harmonic relation) is the name of a type of dissonance that sometimes occurs in polyphonic music, most commonly in vocal music of the Renaissance.
The term describes a "chromatic contradiction" ...
* List of musical intervals
* List of pitch intervals
Below is a list of intervals expressible in terms of a prime limit (see Terminology), completed by a choice of intervals in various equal subdivisions of the octave or of other intervals.
For commonly encountered harmonic or melodic intervals ...
* Ninth#Minor ninth
References
Augmented intervals
Octaves
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