Villa-Lobos wrote his Bachianas Brasileiras no. 9 - the last in the series - in 1945. The work was originally written for an "orchestra of voices" in six parts, though most of us know this piece best in VL's version for strings. As David P. Appleby says in his excellent new book Heitor Villa-Lobos - A Life (1887-1959):
"Even though Bachianas brasileiras no. 9 is a short piece, the writing appears as formidable to today's singers as the vocal writing of Beethoven in the last movement of Symphony no. 9 must have appeared to sopranos of his time. It seems that both Beethoven and Villa-Lobos considered the human voice the ultimate musical instrument to conclude a series of important musical works. Villa-Lobos, concerned with a different vocal timbre for the various voices of the fugue in vocal performance, gave a different syllable to each of the voices. The various performances by stringed instruments are generally able to project the desired contrast of timbre much more easily."
I know of no currently available recordings of the vocal version of BB#9. For those who live in the Boston area, there's a chance to hear this piece live in concert with the Spectrum Singers. Here's the concert information from their website:
Music from the Americas
Friday, May 17, 2002 at 8:00 pm
First Church Congregational, 11 Garden Street, Harvard Square, Cambridge
Irving Fine - The Hour Glass
Heitor Villa-Lobos - Bachiana Brasileira No. 9 for Orchestra of Voices
Harry Somers - Songs of the Newfoundland Outports
William Schuman - Carols of Death
Ernst Bacon - Three American Songs
Conductor: John W. Ehrlich
Luckily, the concert is being recorded for later broadcast on WGBH radio. I will contact the station and try to find out the broadcast date, and post it here.