Inmusic, anoctave (Latin:octavus: eighth) orperfect octave (sometimes called thediapason)[2] is aninterval between two notes, one having twice thefrequency of vibration of the other. 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".[3] The interval between the first and second harmonics of theharmonic series is an octave. In Westernmusic notation, notes separated by an octave (or multiple octaves) have the samename and are of the samepitch class.
To emphasize that it is one of theperfect intervals (includingunison,perfect fourth, andperfect fifth), the octave is designated P8. Otherinterval qualities are also possible, though rare. The octave above or below an indicatednote is sometimes abbreviated8a or8va (Italian:all'ottava),8va bassa (Italian:all'ottava bassa, sometimes also8vb), or simply8 for the octave in the direction indicated by placing this mark above or below the staff.
An octave is theinterval between one musicalpitch and another with double or half itsfrequency. For example, if one note has a frequency of 440 Hz, the note one octave above is at 880 Hz, and the note one octave below is at 220 Hz. The ratio of frequencies of two notes an octave apart is therefore 2:1. Further octaves of a note occur at times the frequency of that note (wheren is an integer), such as 2, 4, 8, 16, etc. and the reciprocal of that series. For example, 55 Hz and 440 Hz are one and two octaves away from 110 Hz because they are+1⁄2 (or) and 4 (or) times the frequency, respectively.
The number of octaves between two frequencies is given by the formula:
Mostmusical scales are written so that they begin and end on notes that are an octave apart. For example, the C major scale is typically writtenC D E F G A B C (shown below), the initial and final Cs being an octave apart.
Because of octave equivalence, notes in a chord that are one or more octaves apart are said to bedoubled (even if there aremore than two notes in different octaves) in the chord. The word is also used to describe melodies played inparallel one or more octaves apart (see example under Equivalence, below).
While octaves commonly refer to the perfect octave (P8), the interval of an octave in music theory encompasses chromatic alterations within the pitch class, meaning that G♮ to G♯ (13 semitones higher) is anAugmented octave (A8), and G♮ to G♭ (11 semitones higher) is adiminished octave (d8). The use of such intervals is rare, as there is frequently a preferableenharmonically-equivalent notation available (minor ninth andmajor seventh respectively), but these categories of octaves must be acknowledged in any full understanding of the role and meaning of octaves more generally in music.
Octaves are identified with various naming systems. Among the most common are thescientific,Helmholtz, organ pipe, 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.
An 88-key piano, with the octaves numbered andMiddle C (turquoise) andA440 (yellow) highlighted
Example of the same three notes expressed in three ways: (1) regularly, (2) in an8va bracket, and (3) in a15ma bracket
The notation8a or8va is sometimes seen insheet music, meaning "play this an octave higher than written" (all' ottava: "at the octave" orall' 8va).8a or8va stands forottava, theItalian word for octave (or "eighth"); the octave above may be specified asottava alta orottava sopra). Sometimes8va is used to tell the musician to play a passage an octavelower (when placed under rather than over the staff), though the similar notation8vb (ottava bassa orottava sotto) is also used. Similarly,15ma (quindicesima) means "play two octaves higher than written" and15mb (quindicesima bassa) means "play two octaves lower than written."
The abbreviationscol 8,coll' 8, andc. 8va stand forcoll'ottava, meaning "with the octave", i.e. to play the notes in the passage together with the notes in the notated octaves. Any of these directions can be cancelled with the wordloco, but often a dashed line or bracket indicates the extent of the music affected.[4]
Demonstration of octave equivalence. The melody to "Twinkle, Twinkle, Little Star" withparallel harmony. The melody is paralleled in three ways: (1) in octaves (consonant and equivalent); (2) infifths (fairly consonant but not equivalent); and (3) inseconds (neither consonant nor equivalent).
After theunison, the octave is the simplest interval in music. The human ear tends to hear both notes as being essentially "the same", due to closely related harmonics. Notes separated by an octave "ring" together, adding a pleasing sound to music. The interval is so natural to humans that when men and women are asked to sing in unison, they typically sing in octave.[5]
For this reason, notes an octave apart are given the same note name in the Western system ofmusic notation—the name of a note an octave above A is also A. This is calledoctave equivalence, the assumption that pitches one or more octaves apart are musicallyequivalent in many ways, leading to the convention "thatscales are uniquely defined by specifying the intervals within an octave".[6] The conceptualization of pitch as having two dimensions, pitch height (absolute frequency) and pitch class (relative position within the octave), inherently include octave circularity.[6] Thus all C♯s (or all 1s, if C = 0), any number of octaves apart, are part of the samepitch class.
Octave equivalence is a part of most musical cultures, but is far from universal in "primitive" andearly music.[7] The languages in which the oldest extant written documents on tuning are written,Sumerian andAkkadian, have no known word for "octave". However, it is believed that a set ofcuneiform tablets that collectively describe the tuning of a nine-stringed instrument, believed to be a Babylonianlyre, describe tunings for seven of the strings, with indications to tune the remaining two strings an octave from two of the seven tuned strings.[8] Leon Crickmore recently proposed that "The octave may not have been thought of as a unit in its own right, but rather by analogy like the first day of a new seven-day week."[9]
Monkeys experience octave equivalence, and its biological basis apparently is an octave mapping of neurons in the auditorythalamus of the mammalianbrain.[10] Studies have also shown the perception of octave equivalence in rats,[11] human infants,[12] and musicians[13] but not starlings,[14] 4–9-year-old children,[15] or non-musicians.[13][6][clarification needed]
^"Music".Vox Explained. Event occurs at 12:50. Retrieved2018-11-01.When you ask men and women to sing in unison, what typically happens is they actually sing an octave apart.
^abcBurns, Edward M. (1999). "Intervals, Scales, and Tuning". InDiana Deutsch (ed.).The Psychology of Music (2nd ed.). San Diego: Academic Press. p. 252.ISBN0-12-213564-4.
^Leon Crickmore.New Light on the Babylonian Tonal System. ICONEA 2008: Proceedings of the International Conference of Near Eastern Archaeomusicology, held at the British Museum, December 4–6, 2008. pp. 11–22.OCLC637006343.
Allen, David. 1967. "Octave Discriminability of Musical and Non-Musical Subjects".Psychonomic Science 7:421–22.
Blackwell, H. R., & H. Schlosberg. 1943. "Octave Generalization, Pitch Discrimination, and Loudness Thresholds in the White Rat".Journal of Experimental Psychology 33:407–419.
Cynx, Jeffrey. 1996. "Neuroethological Studies on How Birds Discriminate Song". InNeuroethology of Cognitive and Perceptual Processes, edited by C. F. Moss and S. J. Shuttleworth, 63. Boulder: Westview Press.
