This topic will be presented in multiple parts as separate blog posts. Part I will start out with a very simple concept and in subsequent Parts the concepts will gain in complexity and build on one another.
In Part I we will look into a very simple concept of chord function and explore what the alternatives are for that function and different ways to think about chord function. If you have studied this concept as part of traditional classical music theory or as part of jazz theory what I’m going to share won’t track 100 percent. The reason being:
Popular music for the most part doesn’t follow those paradigms 100 percent. Classical music theory uses the Bach Chorales as a model and presents a set of rules for chord movement and individual chord part movement. Jazz theory involves a much more complex harmonic language than most popular music makes use of. So what I’ve done is taken some of the concepts from both these traditions and adapted them to the musical language used in folk, pop, rock, blues, fusion, and other popular styles.
Two examples come immediately to mind:
Firstly, in the Blues the Tonic (I7) is a Dominant 7 chord, and so are the Subdominant (IV7) and Dominant (V7). This sets up a totally different chord movement tendency. A lot of pop and rock music has blues influence so you end up with this type of chord usage.
Secondly, if you listen to the early rock music from the 60’s it is obviously a mixing and matching by ear of 1st position guitar chords (C, G, D, Dm, A, Am, E, Em, C, etc…) the result is a harmonic language that formed the early rock song sound and is now totally in our ears as a natural sounding harmonic language. Chord function is circumstantial and there are some “head scratchers” from a Classical Theory perspective.
This blog post assumes a fundamental understanding of chord symbols (CM7, Gm7, F#7, etc…) and chord change notation using Roman Numerals ( I IV ii7 V7, etc…).
If you are unfamiliar with the concepts of Chord Symbol Notation here is a link to an excellent article on the web that you can reference.
OK so let’s get started.
The chords in the key of C major are:
C or I = Tonic
Dm or ii = Supertonic
Em or iii = Mediant
F or IV = Subdominant
G or V = Dominant
Am or vi = Submediant
B(dim) or vii(dim) = Based on the Leading Tone
Chords in a given key fall into three primary categories or “Functions“. They are:
In the simplest form they map to (major key):
Tonic = the I chord
Subdominant = the IV chord
Dominant = V chord
In the key of C major:
Tonic = C
Subdominant = F
Dominant = G or G7
A massive amount of rock music is made up of those chords.
So what about the other chords in the key of C major?
So here’s a picture of how the seven chords of a major key fit into the three primary Functions:
C or I, Em or iii, Am or vi Function as Tonic
F or IV, Dm or ii Function as Subdominant
G or V, B(dim) or vii(dim) Function as Dominant
Here is the key concept:
The chords of a given function are interchangeable.
This is a super simple concept and one that is taken to a mind numbing extreme in Jazz Theory. The concept is called Chord Substitution. The idea is that for any chord in a given progression you can swap out another chord from the same Function group.
Here’s a kind of dumb example but one everyone will immediately recognize in C Major:
We swap Am for C in measure 2 and Dm7 for F in measure 3.
Here’s another example:
In this one we swap Em7 for C and Dm7 for F in measure 2.
We swap Am7 for C in measure 3 and Em7 for C in measure 4.
These are super simple examples and are just meant to demonstrate the concept and obviously don’t represent killer chord progressions.
You can take this simple idea and expand on it by in a number of ways. I’ll be exploring several of these in future Parts/Posts on this topic.
Here’s a very simple one you can try:
Change the quality of any given chord. Change from major to minor, add a 7th or a 9th, or a 6th, etc… Once you start working with the idea of chord substitution it will become part of your compositional process. It is just another tool in the toolbox to Add Variety To Your Chord Progressions.
Give this idea a try and let me know if if you find it helpful by “liking” the post and leave a comment. It would be cool to hear from you.
Thanks for reading this post.
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Let’s all go out there and make some music.