Country music’s relationship with Nashville is but a recent dalliance compared to Music City’s gospel roots. That story extends back into the 19th century, with the establishment of The Fisk Jubilee Singers and the inspiration for the Ryman Auditorium. Nashville’s first music publishers and some of its first radio stations were gospel-based. And in 1921 came the founding of the Fairfield Four, probably Nashville’s most famous gospel vocal group. The lineage of the Fairfield Four thrives and resonates in Odessa Settles, this week’s guest on The String.