at Breadloaf (http://midddigital.middlebury.edu/local_files/robert_frost/lectures_readings/) This is trove of
Frost audio material - his rambling talks during his annual appearances
at the Breadloaf Writers Workshops. Many end with a reading by
him. He never really prepared for talking, so he often rambles
along, but there is good stuff to be mined from it.
Fishhouse Poems (This is a
collection of poetry by various contemporary poets. They got poets to
send their written work and also read it into recording devices.
It gives an interesting archive of spoken poems. A lot of it
does NOT fit the plain-speech resonance category, but it is an
Poet and the Poem series from
Library of Congress site -- lots of hour long audio interviews, in
which poets talk and read some of their work.