The song says “the blues had a baby and they called it rock ‘n roll.” But the blues really had triplets: rock ‘n roll, jazz and of course, soul. And when you talk about a city as steeped in these traditions as Chicago, you know there are a ton of artists that put some soul into their blues, and some blues into their soul. Ayana Contreras digs up a stack of the latter-local soul artists that leaned toward the blues.