In music, an octave (Latin: octavus: eighth) or per-Multi-oct-ave F major chord with oct-aves marked by brackets. Play full chord , lowest oct-ave , middle oct-ave , or highest oc-tave
fect oct-ave is the interval between one musical pitch and another with half or doubles its frequency. It is defined by ANSI as the unit of frequency level when the base of the logarithm is two. The oct-ave 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 most important musical scales are typically written using eight notes, and the interval between the first and last notes is an oct-ave. For example, the C Major scale is typically written C D E F G A B C, the initial and final C’s being an oct-ave apart. Two notes separated by an oct-ave have the same letter name and are of the same pitch class.
Three commonly cited examples of melodies featuring the perfect oct-ave as their opening interval are “Singin’ in the Rain”, “Somewhere Over the Rainbow”, and “Stranger on the Shore”.
The interval between the first and second harmonics of the harmonic series is an oct-ave.
The oct-ave has occasionally been referred to as a
diapason.
To emphasize that it is one of the perfect intervals (including unison, perfect fourth, and perfect fifth), the oct-ave is designated P8. The oct-ave above or below an indicated note is sometimes abbreviated 8va (= Italian all’ottava), 8va bassa (= Italian all’ottava bassa, sometimes also 8vb), or simply 8 for the oct-ave in the direction indicated by placing this mark above or below the staff.
Table of Contents
octave | Understanding Western Music Theory
Theory
For example, if one note has a frequency of 440 Hz, the note an oct-ave above it is at 880 Hz, and the note an oct-ave below is at 220 Hz. The ratio of frequencies of two notes an oct-ave apart is therefore 2:1. Further oct-aves of a note occur at 2n times the frequency of that note (where n 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 oct-aves away from 110 Hz because they are 0.5 (or 2 −1) and 4 (or 22) times the frequency, respectively.
After the unison, the oct-ave is the simplest interval in music. The human ear tends to hear both notes as being essential “the same”, due to closely related harmonics.
An example of an octa-ve, from G4 to G5
“Twinkle Twinkle Little Star” melody doubled in four octaves: consonant and equivalent. Play
Notes are separated by an oct-ave “ring” together, adding a pleasing sound to the music. For this reason, notes an oct-ave apart are given the same note name in the Western system of music notation—the name of a note an oct-ave above A is also A. This is called oct-ave equivalency,
the assumption that pitches one or more octaves apart are musically equivalent in many ways, leading to the convention “that scales are uniquely defined by specifying the intervals within an octave”. The conceptualization of pitch as having two dimensions, pitch height (absolute frequency) and pitch class (relative position within the octave), inherently includes oct-ave circularity. Thus all C♯s, or all 1s (if C = 0), in any oct-ave are part of the same pitch class.
oct-ave equivalency is a part of most “advanced musical cultures”, but is far from universal in “primitive” and early music. The languages in which the oldest extant written documents on tuning are written, Sumerian and Akkadian, have no known word for “oct-ave”.
However, it is believed that a set of cuneiform tablets that collectively describe the tuning of a nine-stringed instrument, believed to be a Babylonian lyre, describe tunings for seven of the strings, with indications to tune the remaining two strings an oct-ave from two of the seven tuned strings.
Leon Crickmore recently proposed that “The oct-ave 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”.
Monkeys experience oct-ave equivalency, and its biological basis apparently is an oct-ave mapping of neurons in the auditory thalamus of the mammalian brain. Studies have also shown the perception of oct-ave equivalence in rats (Blackwell & Schlosberg, 1943), and human infants CHAPTER 8. OC-TAVE
“Twinkle Twinkle Little Star” melody doubled at fifths: fairly consonant but not equivalent. Play
(Demany & Armand, 1984), and musicians (Allen, 1967) but not starlings (Cynx, 1993), 4-9-year-old children (Sergeant, 1983), or nonmusicians (Allen, 1967).
“Twinkle Twinkle Little Star” melody doubled at seconds: neither consonant nor equivalent. Play
While octaves commonly refer to the perfect oct-ave (P8), the interval of an oct-ave in music theory encompasses chromatic alterations within the pitch class, meaning that G♮ to G♯ (13 semitones higher) is an Augmented oct-ave (A8), and G♮ to G♭ (11 semitones higher) is a diminished oct-ave (d8). The use of such intervals is rare, as there is frequently a preferable enharmonic notation available, but these categories of octaves must be acknowledged in any full understanding of the role and meaning of octaves more generally in music.
Notation
Oct-aves are identified with various naming systems. Among the most common are the Scientific, Helmholtz, Organ Pipe, Midi, and Midi Note systems.
An example of the same two notes expressed regularly, in an 8va bracket, and in a 15ma bracket
Six oct-aves on a monochord
In writing, a specific oct-ave is often indicated through the addition of a number after the note letter name. Thus 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 above is “C5”, in a system known as scientific pitch notation.
The notation 8va is sometimes seen in sheet music, meaning “play this an oct-ave higher than written” (all’ ottava: “at the oct-ave” or all’ 8va). 8va stands for ottava, the Italian word for oc-tave (or “eighth”); the oc-tave above may be specified as ottava alta or ottava sopra).
Sometimes 8va is used to tell the musician to play a passage an oc-tave lower, though the similar notation 8vb (ottava bassa or ottava sotta) is more common. Similarly, 15ma (quindicesima) means “play two octa-ves higher than written” and 15mb (quindicesima bassa) means “play two oct-aves lower than written.” The abbreviations col 8, coll’ 8, and c. 8va stand for coll’ottava, meaning “play the notes in the passage together with the notes in the notated octav-es”. Any of these directions can be cancelled with the word loco, but often a dashed line or bracket indicates the extent of the music affected.[11]
For music-theoretical purposes (not on sheet music), octave can be abbreviated as P8 (which is an abbreviation for Perfect Eighth, the interval between 12 semitones or an octave).
First octave
In music theory, the first octave, also called the contra octave, ranges from C1, or about 32.7 Hz, to C2, about 65.4 Hz, in equal temperament using A440 tuning. This is the lowest complete octave of most pianos (excepting the Bösendorfer Imperial Grand). The lowest notes of instruments such as double bass, electric bass, extended-range bass clarinet, contrabass clarinet, bassoon, contrabassoon, tuba and sousaphone are part of the first octave.
The ability of vocalists to sing competently in the first octave is rare, even for males. A singer who can reach notes in this range is known as a basso profondo, Italian for “deep bass”. A Russian bass can also sing in this range, and the fundamental pitches sung by Tibetan monks and the throat singers of Siberia and Mongolia are in this range.
See also
- Blind octave
- Decade
- Eight foot pitch
- Octave species
- Pitch circularity
- Pseudo-octave
- Pythagorean interval
- Solfege