AHM – Root Motion and Reinterpretation of Harmony

This is part of an on-going series on “AHM,” a compositional approach of mine. To get up to speed, scroll down to check out the other posts on the subject, but especially Intro to AHM, Characteristic Pitches and Modal Voicings.

I’ve been struggling to come up with ways of incorporating all of the 28 AH modes into a unified system. When used as chord/modes, they blend very nicely with other chord/modes from the same parent scale, but as soon as you start veering outside of that scale, things start to get dicey. Modal voicings are too potent to be thrown around without some sort of framework.

One possible idea I had was to simply “reinterpret” standard chord progressions from the jazz idiom (or elsewhere) with modal voicings. This way, there’s already the framework, and I just have to plug in my voicings concept. Here are two examples…(click for a larger image)

OK, those sound all right. I’m not particularly enamored with them, but they’re an interesting sound. The original, functional chord progressions rely heavily on building tension and releasing it, whereas the modal voicing reinterpretations of those chord progressions seem to “float” a lot more. Even when the melody (soprano voice) is so cut-and-dry diatonic like in the II-V-I example, the chords themselves don’t smack of tension/resolution. One thing that’s necessary to this whole illusion is that the Mixolydian chord/mode include both the major 3 and the perfect 4. This way the ear isn’t tempted to hear the 3rd (the 7th degree of the parent major scale) resolving to the tonic of the parent key, since the tonic (the perfect 4) is already present within the voicing.

Anyway, let’s see what else we can do by applying modal voicings to conventional minor key chord progressions…

This time instead of staying strictly to a parent key, I borrowed modes from a couple sources in much the same way a jazz improviser would when given a minor key II-V like this. The modal voicings reinterpretation sounds much more laden with dissonance than the major key modal voicing reinterpretation, although it sounds more functional (largely due to the fact that the tonic chord doesn’t have a perfect fourth in it). The I-7 to bVImaj7 is a pretty common sort of modal aeolian progression to begin with, so the differences between the conventional and modal voicings of the chords are minimal.

So cool, we have some new sounds to play with. However, this wasn’t really what I was looking for in coming up with harmony. It’s too constrained to the common practice of jazz, and even though the voicings themselves are novel, the general “feel” of the chord progressions seem stale. Why is that?

Well, a huge part of what makes function chord progressions “tick” is their use of progressive root motion. Understanding the difference between progressive root motion and regressive root motion is something that’s not taught as often as it should in beginning and intermediate theory classes. It’s something I used often while I worked as a student tutor at Berklee to help students come up with chord progressions. Very often, theory teachers blithely assign students assignments that involve inventing chord progressions (like harmonizing a soprano line, for example) without giving them any sort of framework for understanding how to do it. The rest of us, through years of musical training and study, can easily intuit what makes a chord progression sound good within functional contexts (this is why we all know that a V-ii-IV-vi-iii progression might not be the best way to impress your theory teacher.) But why is that?

Very simply, it’s progressive root motion. Root motion is defined as “progressive” if it goes up a fourth, down a third or up a second. It’s defined as “regressive” if it goes down a fourth, up a third, or down a second. One analogy I like is that progressive root motion is the ticking of the clock, and regressive root motion is winding it. You don’t want to wind it too tight (too much regressive motion), and if you need to wind it, wind it at the beginning of the progression. The rule I gave students (because in theory, most students love simple and logical rules to follow and hate vagueries that don’t get them anywhere) was to never use regressive root motion twice in a row. Yes, there are plenty of examples in the common practice and in function harmony where that’s done and it sounds fine, but its solid way to get them thinking “progressively.”

With all this said, for my own writing with AHM, I intend to avoid progressive root motion, especially when it’s in cycle 5 form. It tends to chug along with too much purpose for non-functional harmony. Progressive root motion is too goal-oriented (the tonic, presumably), and one of the nice things about non-functional harmony is that there ISN’T a goal. Although those reinterpretations of the ii-V’s yield some interesting results, they aren’t what I’m looking for at all when I’m looking to write new and interesting modern jazz. If I wanted to do some arrangements of standards for big band, or something along those lines, these kinds of voicing patterns would be very interesting and exciting, but other than that, I can’t see myself getting too much mileage out of cycle 5 progressions.

That said, just for the exercise, I wrote out this version of “All the Things You Are” to see what I could get with this technique of reinterpretation. Here it is…

All the Things Modal Voicings

…and here’s a MIDI file. I didn’t take a very literal approach with the chord symbols, and, especially in the bridge, sometimes inserted an unusual chord/mode, the same way that a jazz improviser might superimpose chromatic harmony or chromatic melody over a diatonic chord. I’m actually quite pleased with how this turned out. It sounds like the chords never resolve, which is exactly what modal voicings are supposed to do. The next time I find myself in a position where I have to use functional-style chord progressions and root motion, I’ll definitely be using this reinterpretation technique. The more I play with it, the more I like it, although it’s not exactly what I had in mind when I first started toying with the idea.

Anyway, stay tuned for more AHM craziness.



1 Response to “AHM – Root Motion and Reinterpretation of Harmony”

  1. 1 jazzman1945 August 25, 2010 at 11:29 am

    Very interesting ideas!
    If you come to these patterns using the system of Joseph Cohn, measuring the density of chords, then we obtain the following:
    In the cadenza Dm7 – G7 – CMaj7 —— [67.5 – 75 – 67.5]

    In the cadenza D Dorian – G mixo – CIo —— [76.5 – 72 – 50.5 ]

    In the cadenza Dm7/b5 – G7/b9 – Cm6 ——-[45 – 52 – 44 ]

    In the cadenza D Loc- G phryg – C mel min —[82 – 62.5 – 81.5]

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