Bidrectional Application of the Scale-Chord Relationship

Probably one of my biggest revelations when learning to compose was understanding a concept that I at that time already had heard before and read about as well. But I couldn't really grasp the impact this simple yet strikingly important concept has on music before.

It is the concept of the scale-chord relationship.

In dry music theory it means that every chord implies a (set of) scale(s) and every scale implies a (set of) chord(s). But it is so much more than this and actually understanding what it means will give your music an entirely new quality.

This whole concept is particularly relevant for Jazz musicians who base a lot of their improvisational approach on it. Seeing a chord of for instance Cmaj7 in the lead sheet implies for them that they could improvise a melody on top of it that for instance is constructed out of notes of C ionian, C lydian or C pentatonic (depending on surrounding context, key signature or taste).

However, this approach seems alot like it's onedirectional in a way that Chord x implies scale y which was my understanding of it for a quite long time.

In reality however, it is a bidirectional relationship which makes things musically way more interesting.

But let's start at the beginning. 

When starting to compose, you develop a fundemantal understanding of how chords and melodies work together. You learn that the three or four notes that are part of your chord can also be the notes that form your melody on top of that chord. You will also realise that some notes in between these notes can work as melody notes, too as long as they occur on weaker beats and somehow resolve to one of the chord tones. Most likely your music will not leave the diatonic space of your fundamental tonality at that point yet so you will feel like somehow any note from your source scale fits as melody as long as you favour the chord tones of the current chord as resolution points.

Only when your harmonic approach expands towards non-diatonic chords or chord extensions you will start to realize that you need to expand your scale material with tones that seem to only work in the brief harmonic situations where you employ non-diatonic chords while with other chords they don't work at all. At latest at this moment you will probably hear about this chord-scale relationship for the first time.

But at least for me at that point, this fundamental approach that I learned before was so engrained into my thinking that I simply didn't care that much about it. Sure, when I change to a non diatonic chord or add a specific tension note I need to use notes from a scale that this chord supported. But my thinking was so hard wired to the approach of "chord dictates scale" that even when I reverse engineered things (writing a melody first), I approached it in the same way. I looked at what chord is outlined by this melody and applied the chord accordingly. I wouldn't have asked "What scale material is used here" and base any decision on that.

And of course this works in many cases and is a perfectly fine approach. It is easy to understand that there is a chord symbol that tells me which notes are part of the chord. Cmaj9, sure that's C, E, G, B and D. Probably ionian, if I feel fancy I will play an f# over it to make it lydian but that's how this works, right?

Not always. Because that is exactly this one directional thinking that prevents you from exploring a world that is way more interesting.

It was when I discovered one of the masterpieces of the 20th century: Daphnis and Chloe by Maurice Ravel that changed my thinking of this fundamentally.

Passages like this suddenly made me realize what this chord-scale thing was all about. He moved chords there and yet it didn't feel like chord change. For instance that first bar on that page:

He's clearly moving chords there, I see a Gb, Fm, Ebm, Db chord in the right hand there. Sure, it seems like a harmonized version of a melody sustaining over an Eb bass (that swings to its fifth). Yet it seems like this all is one "harmony", it doesn't feel like you would need to mark every quarter note as a new chord. And the whole piece more or less works like this. It seems like he's freely moving in one "harmonic field" before moving to the next "harmonic field".

This kind of blew my mind. I was so used to strictly defining a chord through a chord symbol that it didn't really occur to me that this chord was merely only one representation of a "harmonic flield" that existed during its appearance. I started to think in "scale fields" rather than in chords and it was like I had discovered the sorcerer's stone.

Thinking like this gave me the freedom that in a lydian "scale field" I could use any note of that scale to construct chords out of as long as I referenced it back to it's root (e.g. sustaining a bass note that would be the fundamental of that lydian scale).

Here's the opening of my Violin Concerto from 2010 where I used this concept in a very clearly understandable form:

https://soundcloud.com/robin-hoffmann/lydian-dominant/s-F0BGMqfN33q 

This whole section is effectively one "scale field" of a B lydian dominant scale. I literally take the notes from that scale and keep constructing triads or four note chords out of it moving upwards:

Sure, you could also say it is something like Aaug/B, F#m/B, C#/B etc. but that wouldn't be how we hear it. For the listener, that is one specific sounding harmonic field that keeps developing but doesn't change fundamentally. It has a bit the feeling of alternating between tonic and dominant but not really in a way that it shifts the tonality which I found incredibly fascinating when discovering this approach.

And this whole approach doesn't need to happen in such an extent but can also work in small chord progressions like this one (both following examples are a bit rough regarding voice leading but just serve to bring the idea across).

https://soundcloud.com/robin-hoffmann/c711/s-H9olwuLUhgB

The structure in the right hand implies that lydian dominant scale which the plain C7 voicing in the left hand does not. 

You could also colour this chord differently by choosing a different scale:

https://soundcloud.com/robin-hoffmann/c7aug/s-hIwvFGHtnee

You see that in both cases the fundamental harmony is a C7 but with two different scale approaches. A C7 on its own doesn't specify one scale but can work with several different scales. However these two approaches above very clearly narrow the harmonic intent down to just one scale each.

Also note that with the chord changes to F or respective Fm in both cases the scale changes as well. This doesn't happen in all chord progressions, particularly in diatonic progressions you might end up for a long time in the same scale but theoretically, you can switch the scale on every chord, however, it might be desirable in most cases to find rather similar scales between chords so you find ways to connect them to each other.

Of course the longer the "field" sustains, the more you can work with such approaches as above and they do work particularly well on passages that are from the general approach more static in their harmony but still require some motion. 

The bottom line here is to not take a chord symbol as the ultimate defining harmonic guide but just as an implication of what scale material can be used. This whole approach coincides with some of the things that I said in the tutorial series about voicings where the dominance of triadic harmony should be questioned in order to create more fresh sounding harmonies.

However, also understand that the above approach doesn't replace any other approach but expands on it. If you harmonize a children's tune, you would probably not want to apply any "scale field" approach but go for a straight forward approach. But understanding that the scale-chord relationship works in both directions will help to create more colourful and interesting harmonic approaches.

PS: If you don't know the piece Daphnis and Chloe by Ravel that is linked as a Youtube video above, you should invest an hour listening to the whole thing. You will note regret it and also hear a lot of inspirations for film music.