The soprano Julia Bullock—luminous in the music of John Cage, Igor Stravinsky, and John Adams—performs Barber’s poignant work of 1947, Knoxville: Summer of 1915, which the composer himself described as a “lyric rhapsody” for voice and orchestra. Also on the program, conducted by Gustavo Dudamel: Gershwin, Copland, and a world premiere piece from the late André Previn, commissioned by the L.A. Philharmonic (which Previn directed from 1985 to 1989). —L.J.