This falseta is part of a magnificent composition that Jose Luis wrote during his job as musical director for the Ballet of Cristina Hoyos. Taranto is an amazing form and takes years of understanding and experience to be able to accompany the song and dance. This is the first in a series that will definitely blow your mind and make you appreciate this song from much more.
Let's take a look at some of the harmonic devices used:
Key of Taranto: This is the key of F# altered phrygian. I use the word "altered" because it is not the Classical form of Phrygian which would indicate a minor chord as the tonic. Instead of playing F# minor we play the chord as a major chord with the altered tone of the (b9). Hence the F#(b9) harmony. To understand where this harmony comes from you have to look at the home key from where it is derived. First thing to know is that F# Phrygian is the 3rd mode in the key of D major. Second thing is to look at the relative minor key of D major which is B minor. Now most people know that there are 3 forms of minor: Natural minor, Harmonic minor, and Melodic minor. If you look at the second from of minor which is Harmonic minor, the note that is changed is the #7 (B,C#,D,E,F#,G,A#,B). So what happens when you build the chords from this Harmonic minor scale? Well, every chord where the A# appears is going to be altered in some way. The main one of note is the v chord. When you spell out the v chord with the A# you now have F#, A#, C#, E which now becomes a dominant chord (major chord with a minor 7th). This is the most common substitution found when playing in a minor key is to have the V7 chord dominant instead of minor which sound weird. So essentially the "Altered Phrygian" key is borrowing from the relative harmonic minor of the parent key of D major.
Measure 2-3: Jose starts this falseta on the B minor chord minus the 3rd which goes to its chromatic upper neighbor of C. When the 3rd is omitted in chord typically you have more modal options for melody. This is a characteristic of modern rock music.
Measure 4: Here the same neighboring concept is used from the tonic F#(b9) chord except it is the chromatic lower neighbor which gives a nice kind of mirroring effect from the previous measure.
Measure 10-11: This is where the fun starts. Jose starts with a B Harmonic lick which goes straight into the G major 7th harmony, followed by F# minor 7th, leading to the E minor and then back to F#(b9) which is acting more as the V7 chord of B harmonic minor rather than the tonic.
Measure 12-13: Here you see the repeat of the previous idea but then a reharmonization of the C# note in measure 13. By reharmonizing this to an A7 chord the function now changes.
Measure 14-15: The A7 in the previous measure has now acted as the V7 chord in the parent key of D major. This modulation tells a story of hope within the dance. Many of the harmonies that are used in the whole falseta are characteristic of Cristina Hoyos' story she tells through this dance. Kind of hard to explain through words and music without the visual. Its powerful I will leave it at that. So, after the key of D is stated, he then does a popular ii-V7-I progression to reinstate this. (Em, A7, D).
Measure 16-17: Here's where we get the chord that essentially is what we call a pivot chord that will lead us back to the home key of F# altered Phrygian. The A minor 7th! Here this Amin7/G acts as the ii chord of G major. He plays the G major 7th in first inversion with B in the bass, so you kind of get a B minor/ G major polychord.
Measure 18: Here we just came from a moment of thought and question on the G chord/ B minor 6th to then be answered with the remaining sequence of the Spanish cadence and brought back to home. (The term Spanish Cadence refers to the progression that most Flamenco music is anchored in : B minor, A7, G, F#(b9))
Measure 19-20: Here we have the typical chords and legatos used in this from. Note the change to the G minor in measure 20. The II chord gets a lot of different treatments in Altered Phrygian. Changing the II chord to a ii minor is a common occurrence for melodic purposes.