Please note that the content of this book primarily consists of articles available from Wikipedia or other free sources online. In classical music from Western culture, an augmented sixth (Play) is an interval produced by augmenting a major sixth by a chromatic semitone. For instance, the interval from C to A is a major sixth, nine semitones wide, and both the intervals from Câ™ to A, and from C to Aâ™¯ are augmented sixths, spanning ten semitones. Its inversion is the diminished third, and its enharmonic equivalent is the minor seventh. In septimal meantone temperament, it is specifically equivalent to the harmonic seventh (a just interval of 7/4). In the tuning system known as equal temperament the augmented sixth is equal to ten semitones and is a dissonant interval. The augmented sixth is relatively rare. Its most common occurrence is built on the lowered submediant of the prevailing key, in which position the interval assumes a natural tendency to resolve by expanding to an octave built on the dominant tonal degree.