In revival meetings, you had musical formats in which the leader'd sing the first line and then the congregation would sing it—had no hymnbooks, and so you had to do the lining out of the hymns. Blacks also had a tradition from the African past of call-and-response singing—so this was not something newly introduced to them, but appropriating that into Christian hymnody, creating their own types of hymns. A kind of modern-day reminiscence of that is:

I—I heard the voice of Jesus say--

And the congregation comes in:

I--I--I, oh Lord, I heard the voice...

—Larry G. Murphy, Garrett-Evangelical Theological Seminary in The Black Church