page_title: Perfect fourth
section_title: Jazz
hierarchical_section_title: Perfect fourth / History / 20th century music / Jazz
caption_attribution_description: English: Fourths from Herbie Hancock's song "Maiden Voyage"
context_page_description: A fourth is a musical interval encompassing four staff positions in the music notation of Western culture, and a perfect fourth is the fourth spanning five semitones. For example, the ascending interval from C to the next F is a perfect fourth, because the note F is the fifth semitone above C, and there are four staff positions between C and F. Diminished and augmented fourths span the same number of staff positions, but consist of a different number of semitones.
  The perfect fourth may be derived from the harmonic series as the interval between the third and fourth harmonics. The term perfect identifies this interval as belonging to the group of perfect intervals, so called because they are neither major nor minor but perfect.
  A perfect fourth in just intonation corresponds to a pitch ratio of 4:3, or about 498 cents, while in equal temperament a perfect fourth is equal to five semitones, or 500 cents.
  Until the late 19th century, the perfect fourth was often called by its Greek name, diatessaron. Its most common occurrence is between the fifth and upper root of all major and minor triads and their extensions.
context_section_description: Jazz uses quartal harmonies (usually called voicing in fourths).
  Cadences are often "altered" to include unresolved suspended chords which include a fourth above the bass:
caption: Fourths in Herbie Hancock's Maiden Voyage[citation needed]
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