Editing Unison (section)

==Definition==
{{anchor|Divisi|Unison (orchestra)}}<!-- This section is the target of Redirect: Divisi (music) and other links-->
{{Infobox Interval
|       main_interval_name = unison
|       inverse = [[octave]]
|       complement = unison
|       other_names = perfect unison, prime, perfect prime
|       abbreviation = P1
|       semitones = 0
|       interval_class = 0
|       just_interval = 1:1
|       cents_equal_temperament = 0
|       cents_24T_equal_temperament = 
|       cents_just_intonation = 0
}}
{{quote|Two pitches that are the same or two that move as one.<ref name="B&S">Benward, Bruce, and Marilyn Nadine Saker (2003). ''Music: In Theory and Practice'', Vol. I, seventh edition, p. 364. Boston: McGraw-Hill. {{ISBN|978-0-07-294262-0}}.</ref>}}
'''Unison''' or '''perfect unison''' (also called a '''prime''', or '''perfect prime''')<ref>Benward & Saker (2003), p. 53.</ref> may refer to the (pseudo-) [[Interval (music)|interval]] formed by a tone and its duplication (in German, ''Unisono'', ''Einklang'', or ''Prime''), for example C–C, as differentiated from the [[Major second|second]], C–D, etc. In the unison the two pitches have the ratio of 1:1 or 0 [[Minor second|half step]]s and zero [[cent (music)|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: {{audio|Unison piano guitar C.mid|play unison on C, piano and guitar}}; or of the same type: {{audio|Unison piano C.mid|play unison on C, two pianos}}. This is because a pair of tones in unison come from different locations or can have different "colors" ([[timbre]]s), i.e. come from different [[musical instrument]]s or human voices.  Voices with different colors have, as sound waves, different [[waveform]]s.  These waveforms have the same fundamental [[frequency]] but differ in the amplitudes of their higher [[harmonic]]s. The unison is considered the most [[Consonance and dissonance#Consonance|consonant]] interval while the [[minor second|near unison]] is considered the most [[Consonance and dissonance#Dissonance|dissonant]]. The unison is also the easiest interval to [[Musical tuning|tune]]. The unison is abbreviated as "P1".

However, the unison was questioned by [[Gioseffo Zarlino|Zarlino]] as an interval for lacking contrast and compared to a [[point (geometry)|point]] in geometry:{{quote|Equality is never found in consonances or intervals, and the unison is to the musician what the point is to the geometer. A point is the beginning of a [[line (geometry)|line]], although, it is not itself a line. But a line is not composed of points, since a point has no length, width, or depth that can be extended, or joined to another point. So a unison is only the beginning of consonance or interval; it is neither consonance nor interval, for like the point it is incapable of extension.<ref>Thomas Street Christensen (2004). ''Rameau and Musical Thought in the Enlightenment'', p. 76. {{ISBN|978-0-521-61709-3}}.</ref>}}