"It is true that the poet does not directly address his neighbors; but he does address a great congress of persons who dwell at the back of his mind, a congress of all those who have taught him and whom he has admired; they constitute his ideal audience and his better self." ~ Richard Wilbur
Yes, who is the poet's audience? Sometimes, I write with absolutely no audience in mind. I have been known to think more about audience in rewrites, but I'll admit, sometimes I believe it is my own soul that is the audience. I think perhaps this is the very audience Wilbur is addressing.