The women’s vocal ensemble Vajra Voices, directed by Karen Clark, returns for a sublime program of medieval and contemporary music. This concert includes music by Hildegard von Bingen, Guillaume de Machaut, and the extraordinary composer-cellist-vocalist Theresa Wong, who joins Vajra Voices for her new work To Burst, to Bloom: Songs on Poems of the 12th Century Taoist Immortal Sun Bu’Er, composed especially for these singers.