At a glance, the Kennedy Center is hardly a down-getting sort of place, but bringing in Odetta (pictured), Ruth Brown, and Carol Woods with their “Ladies Sing the Blues” show could remedy that with a poultice of country blues, folk music, and R&B from three women who know which end of a microphone is up. Friday at 8:30 p.m. at the Kennedy Center Concert Hall. $6.50-31.50. (202) 467-4600. (Michael Dolan)