MUSIC

William Sharp, a 36-year-old baritone, took first prize Sunday in the Carnegie Hall International American Music Competition for Vocalists. Sharp, of Bergenfield, N.J., and two other finalists in the biennial competition gave hour-long recitals at Carnegie Hall on Saturday. His prize includes a recording contract, a guaranteed number of recitals and cash, worth $75,000 in all. Sharp, 1983 winner of the Geneva International Competition, has already recorded for the Vox-Turnabout and Nonesuch labels and performed with the New York Philharmonic and St. Louis Symphony orchestras.