Augmented seventh Adding a diesis to this makes up an octave. Hence, this interval's complement, the diminished second, is often referred to as a diesis. Augmented seventh In classical music from Western culture, an augmented seventh is an interval produced by widening a major seventh by a chromatic semitone. For instance, the interval from C to B is a major seventh, eleven semitones wide, and both the intervals from C to B, and from C to B are augmented sevenths, spanning twelve semitones. Being augmented, it is classified as a dissonant interval. However, it is enharmonically equivalent to the perfect octave. Since
Short octave composer Peter Philips wrote a pavane in which the left hand plays many parallel tenths. This is a considerable stretch for many players, and become even harder when (as in Philips's pavane), there sometimes other notes included in the chord. Of this piece harpsichord scholar Edward Kottick writes, "The sensuality of effortlessly achieving tenths is so strong, so delightful, that one cannot really claim to know the piece unless it has been played on a short-octave keyboard." A later composer who wrote music conveniently playable only on a broken-octave instrument was Joseph Haydn, whose early work for keyboard was intended