It's been a while since I have done an analysis. A few people have asked about Villa-Lobos Etude No. 1 so I thought I would give it a shot. Download the PDF at the end of this article. My analysis reduces the texture to three essential voices for the most part which I believe clearly shows the voice-leading and harmony. I used a few more voices before the final cadence in order to show the resolution of the augmented sixth chord as well as showing the common tone E in the soprano. Let's go through it bar by bar. Since the work is still under copyright I am unable to include the full score but it should be easy to follow along with your published edition.
The piece is loosely in three sections in the key of E minor;
Section 1, measures 1-10. Basically all functional harmony with mainly parallel tenths between the outer two voices supporting an ascending soprano beginning on a G and rising a sixth to the tonic E (shown with dotted slurs). The E is an eleventh over the bass (B) in measure 9 resolving to a tenth in measure 11 (4-3 suspension).
Section 2, measures 11-22. Chromatically descending tritones over an E bass spanning the octave beginning on the high E, which we reached in the first section, and ending on the E an octave lower in measure 22.
Section 3, measures 23-33. Back to functional harmony comprised basically of a drawn out cadence V/V to V to I with a few interesting things in between like the Italian augmented sixth chord for example in measure 30 along with the plagal cadence afterthought (iv-I) with the final major tonic chord containing the added sixth. I wanted to show that the tonic tone E with its leading-tone (mm. 27-28) ties the harmony of the final section together so I put it in the soprano so you would see and hear it.
It was interesting to me to sing or play the soprano voice in the reduction as you listen to a recording of this etude. This makes the underlying voice-leading very easy to hear.
A few interesting features to note:
The non-functional passing chord in measure 8 which spells an Em7(b5)(11) but clearly works as a passing harmony as the bass ascends chromatically from the subdominant to the dominant (A-Bb-B). I have seen this chord in some jazz charts written as A7(b9)(sus4). It's a great sound that Villa-Lobos seems to enjoy and seems quite common in Brazilian music.
The common-tone (CT) diminished seventh chord in measure 22 which ends the descending tritone passage and brings us back to tonic with its resolution in measure 23.
The C#m7(b5)(11) in measure 26 is that same sound that appeared earlier in measure 8. This time I hear it as a #vi half-diminished seventh in the context of melodic minor voice-leading (C#-D#-E).
As mentioned earlier, the beautiful added sixth final tonic chord also very common in jazz and Brazilian music.
As usual I hope you found this interesting and please let me know your thoughts on this famous study by one of our best known composers for the guitar. I wish you the best in 2015!