I'm trying to put my finger on some of the literature that's come out since the 70's on authorial "voice." In particular I'm interested in specific material on how a writer manages voice in a text, what it means to have an authentic voice etc. A lot of this grows out of the expressivist school, but the concentraion of "voice" as a root metaphor then seems to me to go underground. The metaphor shifts from voice to rhetorical situation, audience etc. The emphasis on persona as "speaker" gets a bit fuzzy. Any suggestions on where the idea of writer as metaphorical "speaker" crops up in later literature?