According to its composer, the luxuriant melodies of the Duruflé Requiem, are “based exclusively on themes from the Gregorian funeral mass.” Additionally, Schubert’s “Tragic” Symphony (No. 4) features lyrical melodies and pastoral dance rhythms. Tonight at 7:30 at Severance Hall, the Cleveland Orchestra will play both pieces. Matthew Halls conducts. Tickets start at $29, and the program repeats at 8 p.m. on Saturday and at 3 p.m. on Sunday. (Niesel)