In music, the word unison can be applied in more than one way: Interval of the unison Unison may refer to the pseudo-interval formed by a tone and its duplication (in German, prime), for example c-c, as differentiated from the second, 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're still perceivable as coming from separate sources, whether played on instruments of a different… (More on Unison)