A voice is the sound or sounds projected by creatures, mainly humans, in the form of speaking, singing, screaming, shouting, etc. A voice is necessary for all spoken languages.
In the musical sense, "voice" has two meanings. One denotes a singer or group of singers sharing a single line, used as a term in a musical score to distinguish it from other instruments. Another is a term used in polyphony to refer to the independent lines in a musical work, especially in fugues.