Augmented seventh 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 an octave can be described as a major seventh augmented by a diatonic semitone, the augmented seventh is the sum of an octave,
Pitch interval Thus the ordered pitch class interval, i<"x", "y">, may be defined as: Ascending intervals are indicated by a positive value, and descending intervals by a negative one. Pitch interval In musical set theory, a pitch interval (PI or ip) is the number of semitones that separates one pitch from another, upward or downward. They are notated as follows: For example C4 to D4 is 3 semitones: While C4 to D5 is 15 semitones: However, under octave equivalence these are the same pitches (D4 & D5, ), thus the #Pitch-interval class may be used. In musical set theory, a pitch-interval class