Richard Powers (author of The Echo Maker) has a fascinating essay in the New York Times about how he writes through dictation. Though is writing method has been noted before in various profiles about him, here he describes the process he uses on his tablet PC. In the process, he gives a little history of dictation from Socrates through Milton and Dostoeyevksy to himself.
Why all this need for speech? Long after we’ve fully retooled for printed silence, we still feel residual meaning in the wake of how things sound. Speech and writing share some major neural circuitry, much of it auditory. All readers, even the fast ones, subvocalize. That’s why so many writers — like Flaubert, shouting his sentences in his gueuloir — test the rightness of their words out loud.