The blues and Gregorian chant …

… Singing For Eternity: Billie Holiday At The House Of The Good Shepherd : NPR. (Hat tip, Dave Lull.) 

Billie Holiday made a single, wry nod to gospel in "God Bless the Child," an ersatz spiritual that quotes a nonexistent Bible verse. The stylized gospel-choir chorus on the 1950 Decca recording highlights the extraordinary difference of Holiday's own voice: soft, talky, its deft modulations of musical syntax filling a surprisingly narrow melodic range. Holiday's is not a gospel voice, if by gospel we mean Aretha Franklin or Whitney Houston in full-throated, multi-octave flights of supplication and praise. Her style was not formed in church, if by church we mean the great variety of Afro-Protestant spaces that nurtured congregants' unquenchable aliveness in the face of racial terror and injustice. But for a scant year in early adolescence, just before or around the time she began singing in cabarets, Billie Holiday did sing in church: the Catholic chapel of a convent reformatory, the Baltimore House of the Good Shepherd for Colored Girls. Her stint in a convent reform school gave Holiday bad-girl cred and an ambitious spiritual discipline, and both went lastingly to her style and her sound. Whatever assaults and privations were dealt to her there, the House of the Good Shepherd was where Billie Holiday learned to arrange the jagged pieces of her life into a coherent persona, where her battered spirit was made the subject of confessional performance and where, in the course of this project of self-fashioning, she received dedicated practice and instruction in singing.