Poema de Itabira: viagem na familia, for voice and orchestra (W442) - later adapted for voice & piano (W443).
"In 1941, Villa-Lobos composed what is perhaps his most ambitious and original work for solo voice with piano or with orchestra, entitled Poema da Itabira, on a text by Carlos Drummond de Andrade, dedicated to Marian Anderson. In his work the composer has endeavoured to use the human voice as a musical instrument, making it in effect the soloist in a kind of concerto for voice and orchestra. The music has no overt Brazilian elements, but may be regarded as impregnated with Brazilian 'atmosphere'."
Denis Stevens, A history of song, W. W. Norton & Company, 1970, p. 315
The Dummond de Andrade poem is available here: http://foleirices.blogs.sapo.pt/65016.html
See this post in The Villa-Lobos Magazine for more on the Marian Anderson connection.
Voice & orchestra
Voice & piano
Villa-Lobos, Heitor, and Carlos Drummond de Andrade. 1947. Poema de Itabira: viagem na familia : para canto e orquestra.
The score of the voice & piano version is available at Di-Arezzo.
I haven't seen this important work on CD. You can hear Baritone Renato Mismetti sing it, in the voice & piano version, with Maximiliano de Brito providing the accompaniment, in this video.
The only recent performance of this work that I've come across was by Adriane Queiroz in Lacrosse WI. It would be great if this great Brazilian soprano were to record this work!