Response to Ong

In Ong's article, "The Writer's Audience Is Always a Fiction," he speaks about the differences between audiences when it comes to writing and publicly speaking. From what I understand, he believes that a writer needs to imagine the type of audience they are writing their book for; who's going to buy it, who's going to find it most useful to them. However, when it comes to speaking, the speaker already has a general idea of who their audience is going to be and therefore does not need to "fictionalize" their audience and put it in sync with their speech.
To help myself better understand this, I related it to going to see a movie. Movie trailers and advertisements tell the audience what the movie is going to be like, and from this a certain type of audience is drawn in. Just as talking or giving a speech would be, the director of a movie has a certain audience in mind and knows that people not interested in that certain genre will not attend. On the other hand, authors need to dig a little deeper and imagine the type of audience that will be reading their work and make sure it appeals to them.