That is very interesting! What is “voice rolling”? Does it have to do with inflection up and down?
Yes, and a lot more. It has to do with the rhythms, pacing, cadences, repetitions, pauses, words used, inflections, pronunciations, emphasis - all of that. It's not usually something one just automatically does. It has to be worked on, practiced and perfected to be good at it. That's why whenever I hear anyone doing it, I know that they are probably up to no good. You don't need it unless you're trying to sway the people listening.
One example my partner always used [making fun of the teevee evangeli$t$ asking for money] was:
[phony deep south accent, very rhythmic]"Bruthaaaaas aaaand Sistaaaaaaahs.[pause]
Retch deeeeeeeeeep into your pock-ets... I say, retch deeeeeeeeeep into your pock-ets...
and continue on, saying not to pull out those coins, that small change, but to pull out the bills, the paper money. It's been a long time ago and I can't really do it or give a good example, but all you have to do is turn on TBN on Sunday and listen to the charismatics working up the congregation during their sermon. Or listen to Jesse Jack@$$ speaking before a large crowd. Or Al $harpton. Or just listen to the Revruuuuunnnnnd Wright "damning America" and preaching BLT. You will certainly recognize "voice rolling" when you hear it. Jesse has the voice rolling down pat 110%! Wright does too.