- William Drabkin
In polyphonic music, one of the individual musical lines that contribute to one or more elements of the music, for example two-part counterpoint, four-part harmony, six-part texture; to avoid confusion with the third meaning of ‘part’ given below, the word ‘voice’ is sometimes used instead, e.g. four-voice fugue. Certain forms or genres are often described by the number of parts or voices their polyphonic structure consistently maintains, for instance, two-part invention, three-voice chanson (chanson à 3). One frequently distinguishes the outer (highest and lowest) parts (Ger. Aussensatz) from the inner (middle) part or parts.
In early polyphony parts were named not according to vocal range or timbre, but on the basis of their function in the contrapuntal design, and part names therefore reflected the hierarchies of parts characteristic of various Counterpoint theories. Such theories initially disussed techniques of taking a pre-existing melody and supplying an additional part: the earliest designations for these two elements are ‘vox principalis’ and ‘vox organalis’ (...