Octave(i) (Fr. octave; Ger. Oktave; It. ottava; Gk. diapasōn;; Sp. octava)
- William Drabkin
(Fr. octave; Ger. Oktave; It. ottava; Gk. diapasōn;; Sp. octava)
The interval between any two notes that are seven diatonic scale degrees apart (e.g. c–c′, d–d′). The term usually implies ‘perfect octave’, which is the sum of five whole tones and two diatonic semitones; however it also covers the augmented octave, which is the sum of a perfect octave and a chromatic semitone (e.g. c–c♯′, d♭–d′), and the diminished octave, which is a perfect octave less a chromatic semitone (e.g. c–c♭′, d♯–d′). Acoustically the octave is the simplest of all intervals, giving a frequency ratio of 2:1 (a 1:2 ratio of string length); it is also the interval between a note and its first harmonic overtone.
To Western and most non-Western musicians, two notes an octave apart are in a sense alike, being different only in their relative registers and often seeming to blend into one another. This acoustical phenomenon has made the division of the frequency spectrum into octaves fundamental to both the understanding and the notation of music. The ancient Greeks, who recognized this phenomenon, called the octave ...