Beyond her role as a musician, Rhiannon Giddens is a curator of lost music and voices, and one of her moving recordings is her cover of Joan Baez’s “Birmingham Sunday.” The bombing of the 16th Street Baptist Church by members of the KKK on Sunday, September 15, 1963 took the lives of Addie Mae Collins, 14; Carole McNair, 11; Carolyn Robertson, 14; and Cynthia Wesley, 14, and seriously injured 14 others.