I've got to admit: this was an interesting concept to bring up. At the end of section one, Ong is discussing how you never really create your own personal audience or, really, even write with a particular audience in mind but how you adopt the audience (and how your writing style is influenced) by authors you have read before. He gives the example of a student writing a typical "What I Did This Summer" essay: he has no conceivable audience so "he has to make his readers up, fictionalize them."
But what I found fascinating was the idea that, say he read The Adventures of Tom Sawyer this summer and has a good concept of "what the book felt like, how the voice in it addressed its readers," so "why not pick up that voice and, with it, it's audience?" This is where I had that a-ha moment because this is something that I have noticed myself doing. When going back over my past works, I can see my own technique changing with the works I was reading at the time. There was a period where my works were more descriptive and romantic in their language, similar to what I read at the time.
Now that I've found myself reading more non-fiction and journalistic-esque pieces, I've noticed a similar shift in that technique. I've picked up the audience of the authors I've read (who have picked it up from writers they've read who have done the same "until the dawn of the written narrative") and adapted their voice. Like the student who's talking about his summer vacation, I don't have a realistic reason to talk to you about this outside of my writing so I've adapted the audience of the blogs I've read before.
Have you ever noticed yourself doing this? Isn't it kind of an interesting phenomena?