In an effort to look into some less demanding music that still displays interesting harmony, I will now turn my attention to two of the best known little pieces written for the guitar; namely Lágrima and Adelita by Francisco Tárrega (1852-1909).
These two brief pieces contain quite a bit of interesting music and I was surprised to discover some interesting details that I completely overlooked in the last thirty or forty years of playing them. As a matter of fact everything I have looked into so far has been a revelation in some respect.
The following will summarize the points of interest harmonically as well as melodically.
The form is ternary (ABA) and is very clearly defined by the parallel key relationships of E major for the first eight measures, followed by E minor for the second eight and the return to E major through the restatement of the A section for the final eight measures.
Parallel tenths alternately define the tonic and dominant harmonies in the first four measures as shown in the reduction staff.
Measures five through eight consists melodically of a descending E major scale supported again by parallel tenths and sixths but in a much less obvious way. In this case the melodic line is not always on the beat, as in measure six where the A is not heard until the second half of beat three and in measure seven where the F# is heard on the second half of beat two and would be best sustained over the third beat since the D# on the second half of beat three is actually part of an ascending middle voice (C#-D#-E). The reduction makes this clear. Notice how the tenths in measure five are converted to sixths in measure six through the change in direction of the lower voice. Also notice the descending chromatic voice in measure seven that generates the secondary dominant (V/V).
Measures nine through sixteen (B section) is in the parallel minor key of E minor and is quite straightforward. The reduction staff shows the basic voice-leading. Notice how the ascending tenths in measure thirteen continue into measure fourteen with the A dropping down an octave and the C occurring a bit late (second half of beat one). Also notice the actual voice-leading of measure fifteen in the reduction staff in which the F# on beat two is the melody and the notes that follow are again part of an inner voice which descends to the G of the tonic chord in measure sixteen.
I think this one is the more interesting of the two. The form is the same with the key relationships reversed this time.
The A section (mm. 1-8) reduces melodically to a descending E minor scale with the interesting twist of including the raised seventh (D#) as well as the natural seventh (D-natural) scale degree in the descent as shown in the reduction staff. Also present in measures three and seven is the augmented dominant seventh chord (B7#5). This harmony can be shown as a product of the occurrence of an accented passing tone (G) between the seventh of the chord (A) and the fifth (F#) as shown in the reduction staff. Whether or not this chord is a stand-alone harmonic structure is debatable. Usually it occurs, as this one does, in the context of an accented passing tone. Its function is almost always dominant.
The B section (mm. 9-16) contains two interesting harmonic features:
1) The secondary dominant (V/V) F#7 chord that is heard in measure eleven that is missing the all important third (A#). I think you will agree that the implied harmony here is clearly a dominant seventh chord even without the third being present. It would make the execution of the ornamental mordent figure difficult and I am sure that is the reason for the omission.
2) The Italian augmented sixth chord heard in measure fourteen. A rather dramatic moment that should be savored (explains the inclusion of the fermata). As usual this harmony prepares the dominant as it does in this case with the resolution of the augmented sixth interval (C-A#) in contrary motion to octave B’s. Note harmonically that the tonic 6-4 chord (dominant with a double appoggiatura or suspension depending on the context) precedes the true dominant as it often does at cadences.
These pieces contain some nice examples of basic harmony as well as a few more advanced features like secondary dominants, augmented chords and the often difficult to understand augmented sixth chord. By associating these concepts with real music with which almost all guitarists are familiar should make them more comprehensible. It is always better to associate theory with practice when possible. The pdf below contains the score and analysis.