Versions of “In dulci jubilo” by Bach, Pearsall and Jetse Bremer, along with Fantasia on Christmas Carols by Ralph Vaughan Williams and a premiere carol set to words by Hildegard von Bingham will be among the highlights of “In Sweet Joy,” the Southern Oregon Repertory Singers’ holiday concert, to be pressented at 7:30 p.m. Saturday, Dec. 17, and 3 p.m. Sunday, Dec. 18, in the Music Recital Hall on the Southern Oregon University campus, 1250 Siskiyou Blvd. Paul French directs. Musicologist Ed Wight will present a lecture one hour before each performance. Tickets cost $20, $5 for students, and are available at Paddington Station and Music Coop. Tickets also are available at www.repsingers.org or by calling 541-552-0900.