Frost at Breadloaf
( 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 interesting resource.

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.