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In music, one voice per part (OVPP) is the practice of performing Baroque choral music, and Bach's works in particular, with a single voice on each vocal line. Choral works featuring SATB (soprano, alto, tenor and bass) vocal parts are consequently sung by four singers when this approach is adopted.
The first conductor to strongly advocate this approach to the music of Johann Sebastian Bach was the American pianist and conductor Joshua Rifkin in the 1980s. The use of solo voices in the choral music of Bach has also found champions in Andrew Parrott, Paul McCreesh, Sigiswald Kuijken and Konrad Junghänel. The approach is still somewhat controversial and recordings of Bach's music featuring solo voices in choral movements have met with mixed reviews. Proponents cite the fact that there are rarely additional copies of the vocal parts. One reason for not favouring one voice per part is that there is evidence that Bach preferred to use more singers in performances at Leipzig. Furthermore, the presence, absence and omission of solo and tutti markings in scores, as well as the ambiguity in their meaning, brings further doubt to the question of whether Bach used more than one singer per part or not.
The initialism OVPP was first coined in the Internet mailing list "The Bach Recordings Discussion Group" in the mid 1990s by Steven Langley Guy. The initialism seems to have been adopted more widely since that time.