Through the wonders of the Google search engine, I found what I consider to be a very good article called An Introduction To Black Preaching Styles. That article was written in 1986 by Geoff Alexander, and is the transcription of a cassette that he prepared "with keyed examples of excerpts from sermons".

In the interest of preserving portions of this document, I'm going to post long passages of it on this thread.

AN INTRODUCTION TO BLACK PREACHING STYLES

...The black sermon is stated in the vernacular, with inflection and timing so musical that many have compared it in style to improvised jazz. Much of the sermon is improvised around a matrix both sacred and profane, and the style is cohesive enough that one can enter virtually any black Baptist, Methodist, or Pentecostal church from coast-to-coast and hear a sermon of similar form. This is assured in part by the congregation, which answers the preacher verbally at every opportunity, creating a call-and-response pattern, which often builds to a frightening intensity...

Whether he be pastor, preacher, healer, or evangelist, the key to the success of the Black Christian orator will ultimately lie in his interaction with the congregation. Unlike many white congregations, the black membership will shout words of encouragement, affirmation, or repeat whole phrases as a way of interaction with the ministry. They are not preached to as much as they are preached with; this will be readily apparent upon listening to the accompanying tape. This rhythmically musical call-and-response is an essential part of the black sermon, and one of the main differences between it and the white Pentecostal service.Bruce Rosenberg describes the congregation as follows:

"Everyone is sweating all the time...cardboard hand fans with mortuary advertisements are swished back and forth, giving ...an undertone of humming...No real effort is made to stop children from giggling or...infants from crying... The women usually sit together in front with their young... The men, who are relaxed and jovial as they joke outside, come in at the last moment and sit near the back. At many services, one or two of them sleep through the sermon" (5,12). Rosenberg also notes the ever-present handkerchief used by the preacher to wipe the sweat off his brow, his gyrations and wild gesticulations...

The Black Sermon is formulaic, but relies upon improvisation often inspired by the congregation to fill out the formula of the sermon. Of all the texts I have read on the subject, I find Gerald Davis' to be the most insightful as to the definition and categorization of the sermon itself, and therefore will use his findings extensively in this chapter. Davis defines the sermon as "a narrative system which incorporates rationalized sets of conventions and principles designed to support the articulation of existence, belief, and cosmologic considerations in the experiencing lives of African-American people." Davis then sets five formulaic boundaries that occur within the sermon itself, each of which must be performed in predefined order:

A. Preacher indicates that text was provided under divine inspiration.
B. Identification of the theme of the sermon, followed by appropriate quotation from the Bible.

C. Interprets, first literally, then broadly, the quoted Bible passage.

D. Independent, theme-related formulas, developing or retarding a sacred/secular tension and moving between abstract and concrete example. Each formula is an aspect of the "argument" of the sermon.

E. Closure as such is rarely found in the black sermon, but more commonly there will be a brief moment of testimony, or an affirmation of faith by the preacher. (3,67-82)

The sermon itself is usually prefaced by a prayer and music, which in itself is lively enough that the congregation will be moved by the spirit sufficiently to be an attentive and vocal audience for the sermon. Most preachers are good singers, but trust the music director of the church to provide the musical program...

Black preaching is built upon a hemistich system of rhythmic repetition, in which the pulses are felt rather than strictly metered...

The listener will notice how quickly the congregation keys into this hemistich rhythmic pulse, which is a basic part of contemporary Black preaching styles.

One of the foundations of the style is a constant push/pull between the sacred and the secular. [Rev] Thomas' references to dope addicts, alcoholics, and prostitutes are typical of the Black sermon, and deal with issues and people that the congregation, particularly in large cities, find in their daily lives.

Thomas also uses certain phrases as refrains, which, although not cited as often as the theme itself, lend almost an ode-like quality to the piece...

[The] his notion of parallelism, [is] consistent with the rhythm and poetry of the black sermon...

The mark of a brilliant preacher is the way he moves in and around themes and manages to eventually tie them all together, and Thomas' particular genius is confirmed by the fact that ten minutes into the sermon, with emotion rising in the congregation, he still has the poetic presence of mind to tie in the grand theme at the closing of the parallel "But" sequence.

Thomas is also a user of the "exemplum," a section of the sermon in which the preacher gives an example in story form which emphasizes the point of the sermon. The exemplum in this case is his illustration of what happens to someone who, after tying himself to the tail of a calf, doesn't know whether to let go or hold on once it "shakes loose" and starts to run away.

Approximately eleven minutes into the message, Thomas begins half-singing half-talking chant which will eventually evolves into full-fledged song.The song itself begins with the refrain "I found out..." and is answered by the congregation in responses such as "well..." or "yes..." These comments fall into the category known as sermonphones (3,99), and can fall into several classes, three of the most popular being one-word sermonphones ("well…"), phrase sermonphones ("thank you Jesus!"), and non-articulated sermonphones, which are so prevalent in the black sermon that I will have several examples further in the cassette, and generally consist of unintelligible grunts, whoops, groans and hums...

In ending his sermon, Reverend Thomas returns to parallelism, with the word "Evvvery...!" acting as the beginning to truncated sentences, and we can hear his voice fading in and out on the tape as he walks back and forth and side to aide from the pulpit. When he sings "I feel him!" the screams from the congregation begin and pandemonium results as the members fall into the spirit of God, and foot stomping and shouted sermonphones such as "Yes Lord" and "Yes sir!" threaten to drown out the animated Reverend. He closes his sermon with a recommendation to get right with God, followed by a closing hymn from the choir"...