Btw, Blind Will,

I know that you only gave us a teaser, but I'm wondering why you didn't mention call & response vocal [not to mention instrumental] patterns in your initial comments.

Just as background for some who may not be aware of this pattern, see this quote:

"One predominant style of music that is still retained and was brought to America during the slavery period of the early 1600s to 1865, is the call and response pattern in which a leader sings a line and the entire group answers. Typical styles also included drums and other percussion instruments played a complex rhythmic accompaniment. (Sound familiar? A good example of this call and response style with syncopated rhythms can be heard by Ray Charles who used this to great advantage on his hit "What'd I Say")."

Source: Crosscurrents: History of Gospel Music

That website begins the discussion of this subject with this quote:

"There can be little doubt that shouting is a survival of the African "possession" by the gods... it is a sign of special favor from the spirit that it chooses to drive out the individual consciousness temporarily and use the body for its express..."
-Zora Neal Hurston,
The Sanctified Church