Music Director Peter Oundjian continues his tradition of ending the season with glorious music by Mahler. The composer built his Fourth Symphony around his own song “The Heavenly Life,” which borrows text from a Bavarian folk poem. “The angelic voices gladden our senses,” the poem proclaims, “so that everything awakens for joy.” Mahler’s sunniest symphony invokes bells, harp, and woodwinds; in keeping with the lightness of the work, Mahler insisted the soprano perform “with childlike, cheerful expression;” soprano Karina Gauvin joins the Festival in this role. This final concert of the season includes Ravel’s colorful twist on the Shéhérazade tales — again featuring Gauvin’s “glowing, flexible tone” (Opera News) — and the overture to Strauss’ most famous and farcical operetta, Die Fledermaus.