Ok, so there will be no dancing on this post, but I do think that it is important to pinpoint where Longinus and Bakhtin seem to overlap when it comes to an audience's role and responsibility in regard to text and utterances. In 'The Problem of Speech Genres," Bakhtin says "that when the listener perceives and understands the meaning (the language meaning) of speech, he simultaneously takes an active, responsive attitude toward it" (Bakhtin 68). Here, Bakhtin is saying that there is more to speech than just a speaker and that a big component of it is the listener because of the interaction that occurs between speaker and listener. The speech expresses something but it is the listener that takes the language and interprets it, either agreeing or disagreeing with it, drawing from personal experience or reflection to augment the words the speaker uses. The interactions between speaker and listener would be immensely different if, say President Obama was speaking at a Tea Party convention as opposed to speaking to congress (though I'm sure some would say there is little difference at all).
This is where Longinus enters the fray with his excerpt form On the Sublime, indicating that it is the audiences (and in all actuality, human) "nature to be elevated and exalted by true sublimity" (Longinus 350). I'm not saying that President Obama delivers speeches that are sublime (though some do take the improvement over the predecessors speeches as a step, or ten, in the right direction), but I do think that, when applying Longinus's idea of our nature in regard to sublimity, it is our job to interpret and discover if his speeches satisfy that need for sublimity. That President Obama would face polarizing reaction depending on the venue underscores the lack of sublimity in his speech, since it is not all encompassing and effective in the same way even with different audiences. At least this is what I think Longinus means when he says "When people of different trainings, ways of life, tastes, ages, and manners all agree about something, the judgement and assent of so many voices lends strength and irrefutability to the conviction that their admiration is rightly directed" (Longinus 350).