In music, unison is two or more

musical parts A part (or voice) generally refers to a single strand or melody or harmony of music within a larger ensemble or a polyphonic musical composition. There are several senses in which the word is often used: * the physical copy of printed or writte ...

that sound either the same pitch or pitches separated by intervals of one or more

octave In music, an octave ( la, octavus: eighth) or perfect octave (sometimes called the diapason) is the interval between one musical pitch and another with double its frequency. The octave relationship is a natural phenomenon that has been refer ...

s, usually at the same time. ''Rhythmic unison'' is another term for homorhythm.

Definition

Unison or perfect unison (also called a prime, or perfect prime)Benward & Saker (2003), p. 53. may refer to the (pseudo-) interval formed by a tone and its duplication (in German, ''Unisono'', ''Einklang'', or ''Prime''), for example C–C, as differentiated from the

second The second (symbol: s) is the unit of time in the International System of Units (SI), historically defined as of a day – this factor derived from the division of the day first into 24 hours, then to 60 minutes and finally to 60 seconds ...

, C–D, etc. In the unison the two pitches have the ratio of 1:1 or 0 half steps and zero cents. Although two tones in unison are considered to be the same pitch, they are still perceivable as coming from separate sources, whether played on instruments of a different type: ; or of the same type: . This is because a pair of tones in unison come from different locations or can have different "colors" ( timbres), i.e. come from different

musical instrument A musical instrument is a device created or adapted to make musical sounds. In principle, any object that produces sound can be considered a musical instrument—it is through purpose that the object becomes a musical instrument. A person who pl ...

s or human voices. Voices with different colors have, as sound waves, different waveforms. These waveforms have the same fundamental frequency but differ in the amplitudes of their higher

harmonic A harmonic is a wave with a frequency that is a positive integer multiple of the ''fundamental frequency'', the frequency of the original periodic signal, such as a sinusoidal wave. The original signal is also called the ''1st harmonic'', the ...

s. The unison is considered the most consonant interval while the near unison is considered the most dissonant. The unison is also the easiest interval to tune. The unison is abbreviated as "P1". However, the unison was questioned by

Zarlino Gioseffo Zarlino (31 January or 22 March 1517 – 4 February 1590) was an Italian music theorist and composer of the Renaissance. He made a large contribution to the theory of counterpoint as well as to musical tuning. Life and career Zarlino w ...

as an interval for lacking contrast and compared to a

point Point or points may refer to: Places * Point, Lewis, a peninsula in the Outer Hebrides, Scotland * Point, Texas, a city in Rains County, Texas, United States * Point, the NE tip and a ferry terminal of Lismore, Inner Hebrides, Scotland * Point ...

in geometry:

Performance ensembles

In orchestral music ''unison'' can mean the simultaneous playing of a note (or a series of notes constituting a

melody A melody (from Greek language, Greek μελῳδία, ''melōidía'', "singing, chanting"), also tune, voice or line, is a Linearity#Music, linear succession of musical tones that the listener perceives as a single entity. In its most liter ...

) by different instruments, either at the same pitch; or in a different

, for example, cello and double bass (''all'unisono''). Typically a section string player plays unison with the rest of the section. Occasionally the Italian word ''

divisi In musical terminology, ''divisi'', or as typically printed ''“div.,”'' is an instruction to divide a single section of instruments into multiple subsections. This usually applies to the violins of the string section in an orchestra, although v ...

'' (meaning ''divided'', abbrev. ''div.'') marks a point where an instrumental section, typically the first violins, is to be divided into two groups for rendering passages that might, for example, include full chords. Thus, in the ''divisi'' first violins the "outside" players (nearer the audience) might play the top note of the chord, while the "inside" seated players play the middle note, and the second violins play the bottom note. At the point where the first violins no longer play ''divisi'', the score may indicate this with ''unison'' (abbrev. ''unis.''). When an entire choir sings the main melody, the choir usually sings in unison. Music in which all the notes sung are in unison is called monophonic. In a choir with two or more sections, such as for different vocal ranges, each section typically sings in unison. Part singing is when two or more voices sing different notes. Homophony is when choir members sing different pitches but with the same rhythm. Polyphony is when the chorus sings multiple independent melodies.

Synthesizer

synthesizer A synthesizer (also spelled synthesiser) is an electronic musical instrument that generates audio signals. Synthesizers typically create sounds by generating waveforms through methods including subtractive synthesis, additive synthesis and ...

s, the term ''unison'' is used to describe two or more

oscillator Oscillation is the repetitive or periodic variation, typically in time, of some measure about a central value (often a point of equilibrium) or between two or more different states. Familiar examples of oscillation include a swinging pendulum ...

s that are slightly detuned in correspondence to each other, which makes the sound fatter. This technique is so popular that some modern virtual analog synthesisers have a special oscillator type called " super saw" or "hyper saw" that generates several detuned sawtooth waves simultaneously.

Definition

Performance ensembles

Synthesizer

See also

References

Further reading