page_title: Octave
section_title: Octave of a pitch
hierarchical_section_title: Octave / Notation / Octave of a pitch
context_page_description: In music, an octave or perfect octave is the interval between one musical pitch and another with double its frequency. The octave relationship is a natural phenomenon that has been referred to as the "basic miracle of music", the use of which is "common in most musical systems". The interval between the first and second harmonics of the harmonic series is an octave.
  In Western music notation, notes separated by an octave have the same letter name and are of the same pitch class.
  To emphasize that it is one of the perfect intervals, the octave is designated P8. Other interval qualities are also possible, though rare. The octave above or below an indicated note is sometimes abbreviated 8ᵃ or 8ᵛᵃ, 8ᵛᵃ bassa, or simply 8 for the octave in the direction indicated by placing this mark above or below the staff.
context_section_description: Octaves are identified with various naming systems. Among the most common are the scientific, Helmholtz, organ pipe, MIDI, and MIDI note systems. In scientific pitch notation, a specific octave is indicated by a numerical subscript number after note name. In this notation, middle C is C₄, because of the note's position as the fourth C key on a standard 88-key piano keyboard, while the C an octave higher is C₅.
caption: An 88-key piano, with the octaves numbered and Middle C (cyan) and A440 (yellow) highlighted