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Harmonic Relativity & Chord Relationships
#improvisation #harmony #music-theory #isomorphic-instruments #relative-pitch #composition
6 min read
Limits of classical Harmonic Theory
The standard way harmony is taught in Western pedagogy would gravitate around the Tonal Framework, Roman Numerals, Functional Harmony and Cadences.
In this system, music centers on a key, defined by a home pitch called the tonic and its corresponding major scale.
Chords built on each scale degree define the standard chord set available for progressions. Those chords are labeled using Roman Numerals corresponding to their scale degree position in the key.
In the key of C, the I chord would be C, V would be G, ii would be Dm.
Functional harmony adds a notion of each chord having a role to play within a key. Some chords are restful (tonic), others set up tension and lead away (predominant), and yet others are so tense they need to resolve to the tonic (dominant).
Building from there, you get cadences — the resulting movements from one chord to another. V to I, the authentic cadence, creates a strong sense of resolution, whereas a IV to I plagal cadence is often described as softer or more reflective.
At its core, this is a closed system. It juggles seven diatonic chords, with some considered more stable than others, and proposes a sense of natural flow, where certain chords seem to “want” to resolve to others.
It served anyone from Handel and Vivaldi to Brahms well, and we can hear how much structure was added to music thanks in part to the development of this system. The sense of tonal hierarchy and directional harmonic flow became far more pronounced.
The core criticism I have is simple: it is much too narrow a system.
Music evolved beyond the Common Practice Period. The system finds itself ill-suited to describe even earlier music from the Renaissance and Medieval periods that were built on a modal understanding of harmony. It similarly struggles with Romantic, Impressionistic, or Modernist works — and jazz routinely ventures so far outside its confines that it becomes barely recognizable.
Contemporary practices show that the framework can be stretched with tools such as secondary dominants, borrowed chords, modal mixtures, and pivot chords. Yet the deeper you dig, the more working within it feels like constant patching and retro-fitting. We’re forcing awkward labels onto naturally emerging harmonic ideas instead of accepting them as they are.
In other words, we’re teaching a local grammar as if it were a universal language.
This system should really be thought of as Common Practice Period harmonic theory rather than a general framework for all of music.
Strict adherence to it can lead to formulaic, predictable results — similar rules tend to produce similar music. But deviating from it is cognitively demanding: one must keep track of shifting key centers, modulations, and second- or third-order detours.
A useful harmony system should not treat chromaticism, modal mixture, or tonal ambiguity as exceptions, but as core features of musical expression. In practice, the traditional model often breaks down when tested against real-time improvisation or expressive scoring.
The state of affairs calls for a fundamental re-framing, not yet another patch.
Chord Relationships promises
There exists a different, simpler, and more universal organizing framework for harmony that I’d like to share.
Credits where they’re due: I learned it from composer J. Jay Berthume in his presentation “Harmonic Relativity”, which I highly recommend watching — it can be quite eye-opening.
At its core, this system is a phenomenological taxonomy: it describes what actually occurs in music rather than prescribing what should happen.
It is also atomic — instead of trying to explain why entire progressions work, it focuses on the smallest unit of harmony: the movement from one chord to the next.
These movements act like lego bricks, freely recombined and arranged to create larger structures. The approach is genre-agnostic and remarkably flexible.
It also describes harmony in relative terms rather than absolutes, matching the relative nature of human hearing. This is crucial, because our perception of harmony depends on motion and relationship, not on fixed tonal references.
For that reason, the system proves especially useful to game and film composers, as well as improvisers, who see harmonic gestures as direct pathways toward the emotional effects they want to evoke in listeners.
Notation
The Chord Relationship is the fundamental unit of this system and can be abbreviated as “CR.” A CR represents the movement from one chord to the next.
Its notation is made of three distinct parts:
- the quality of the departure (root) chord,
- the interval separating the two chords,
- the quality of the target chord.
Chord qualities are drawn from a set of four basic triads — major, minor, diminished, and augmented. These were chosen because they remain the foundation of most contemporary harmony, while keeping the system simple and workable.
They are abbreviated with their familiar shorthand letters: M, m, d, and A.
The interval between chords is described using Roman numerals such as ♭V, II, ♭III, IV, and so on.
Put together, a Chord Relationship looks like this:
M III M, M ♭II M, m IV M, m ♭III m, m VII M.
You’ll notice right away that there is a finite number of possible CRs.
With 4 potential qualities for the root chord, 4 for the target chord, and 12 possible intervals between them, we get 4 × 4 × 12 = 192 total CRs.
Of these, only 33 can be derived from the diatonic scale (3 of which are static CRs and not especially noteworthy).
Those remaining 30 make an excellent starting point when first exploring the system — simple enough to handle, yet broad enough to reveal its expressive potential.
In essence, this framework maps all possible chord-to-chord movements in an organized way.
It doesn’t dictate what should be done — it simply lays out the harmonic landscape available to explore.
Emotional colors
To illustrate what makes this system as useful as it is, let’s take a look at some colorful CRs.
Example 1 – M ♭II M
Here is M ♭II M.
It often feels spicy, Spanish or Mexican, warm, tense, fiery, flamenco-like.
Whenever you want to evoke that flavor, you can turn to this CR — in improvisation or composition alike.
All you’d need is a major chord moving a minor second upward into another major chord.
Example 2 – M III M
M III M has a completely different energy — lush, radiant, surreal, majestic, bright.
Once you recognize that sound and associate it with a feeling, it becomes a reliable tool in your harmonic vocabulary.
Example 3 – m VII M
m VII M might feel melancholic, yearning, tragic, or resigned — yet still dignified or faintly luminous.
Example 4 – m ♭III m
In contrast, m ♭III m conveys a deeper, heavier kind of tragedy — darker, more poignant, even a sense of doom.
The differences can be subtle, which is why listening and feeling each CR is essential.
This system emphasizes emotional effect above theoretical labeling: there’s no layer between your intent and the harmonic gesture that delivers it.
Stringing CRs together
Building a progression
So how would one write a chord progression using Chord Relationships?
You simply:
- Pick a set of CRs that match the emotional color you’re after.
- String them together — a CR that ends on a major chord must be followed by one that begins with major; if it ends on minor, the next starts with minor.
That’s it.
As long as the CRs align emotionally, the resulting progression will reliably elicit the feeling you intend — at least from a harmonic standpoint.
Example 1 – Tender and Melancholic
Let’s create a tender-sounding progression, something with a bit of melancholy and attachment.
Here’s a set of CRs that match that idea:
m ♭VI M, M VII m, m ♭VII M, M VI m.
Combining them gives us the following:
And with a simple melody added for contour:
Example 2 – Unease and Wonder
Now let’s try something contrasting: a sound that conveys friction, wonder, and unease.
The CRs I’m hearing are:
m ♭V M, M ♭VI M, M ♭III m, m VII M.
Each of these has an interesting, slightly unstable character.
Here’s a progression using them:
And with melody:
Hopefully it doesn’t sound cliché, but instead remains on target emotionally — illustrating how effective this approach can be for scoring or expressive improvisation.
Closing thoughts
This article is running long and time is running short, so I’ll leave it here for now.
I’ll make sure to revisit the topic soon to add complementary information and explore further applications of this system.