Harmonic Function: What you need to know (part 1)

In this post, we’re going to look at how to use the circle of 5ths as a guide for determining where a chord wants to move and why it wants to move there. Having a good grasp of this concept at a basic level will be helpful later on when incorporating more complex chords and in understanding modulation.

I’ll be using roman numerals and chord symbols to explain how this works, as well as the common names used to identify a note or chord’s position in the harmonic hierarchy. The image below contains all the information you’ll need to know, but we’ll be looking at it in a completely different order in the process. We’re going to see that the distance between notes and chords when considering how they function is much greater than when we think of them according to their position in a scale.

basic harmonic language

Tonic and Dominant

Everything will begin and end with the tonic and nothing gets to the tonic without first passing through the dominant. A general rule for what we’ll be doing is that from where ever we leap to from the tonic, we have to find our way back by moving counterclockwise through each subsequent step along the circle of fifths. This first one is easy, but it’s also the most important.

tonic dominant

For each new function that gets introduced, along with an illustration of how it appears on the circle of 5ths, we’ll also look at how it’s written in a progression using the appropriate roman numerals and chord symbols. I recommend playing through these examples in what ever manner you like and any instrument of your choosing.

tonic dominant progression

The tonic and dominant chords above establish that we are in the key of C, which means that all the chords that follow will reflect that and will not have any accidentals. If you’re going to play these on the piano, that means that all the chords will fall only on white keys; nice and easy.

Supertonic

Now, from the tonic, we’re going to jump a little further to the supertonic. Even though we refer to this as the two chord and its root appears to be directly above the tonic in a scale, this is not how it got its name. The supertonic is named as such because it is a perfect 5th above the dominant, where as the tonic falls a perfect 5th below. So in functional terms, our ‘D’ is actually separated from ‘C’ by the interval of  a 9th, the distance of two perfect 5th, and not a 2nd.

supertonic

So we leap to the supertonic, but have to pass through the dominant in order to get to the tonic. This progression is usually referred to as a ii-V-I (two-five-one) and is frequently used in jazz music as a means of modulation between keys.

supertonic progression

Submediant

The further we get, we begin to see more similarities between chords. As we move next from the tonic to the submediant, we see that they have two notes in common. Even though the root from one to the other might look like a 6th, or a 3rd in its inversion, the functional distance is now three perfect 5ths from the tonic.

submediant

With each jump from the tonic, we’re extending the progression further along the circle of 5ths. We’re also strengthening the resolve of the tonic and its role as the tonal center, as if the further away we go, the more momentum and determination there is to end up there. This progression can be referred to as a six-two-five-one.

submediant progression fix

And for its name, where the prefix super implied something above, sub implies below. The submediant is located a perfect 5th below our next chord.

 Mediant

The mediant, like the submediant before it, also shares two notes with the tonic; but not the same two. The relative distance between the mediant and the tonic is only a 3rd, or a 6th in its inversion, but it’s a much further harmonic distance when looking at them on the circle of 5ths. Although not perfectly, the mediant gets its name because it falls between the tonic and dominant.

mediant

Also called a three-six-two-five, this progression is commonly used in jazz as a way to create an extended ‘outro’ to a tune. Because the mediant shares two notes with the tonic, it’s able to retain the same sense of key but with less finality. Also called a turn-around, this progression only resolves to the tonic following the final passing of the dominant chord; it can go on for a quite a long time.

mediant progression

Leading tone

The chord built on the leading tone is the only diminished triad we’ll find in all of this mess. But we’ve also already seen it, though slightly disguised; it makes up the upper half of the dominant seventh chord. In fact, its the diminished 5th interval that makes the dominant chord so dominant. On its own, it’s the only triad in a major key where the 5th is not perfect. 

leading tone

In sound and in name, the root of this triad is leading to the tonic. As the last note of an ascending major scale, it’s a name that is well-deserved. As a triad, and in the grand scheme of harmonic function, however, the leading tone has to find the tonic by descending according to its place on the circle of 5ths just as all the others do.

leading tone progression

You may be inclined to think otherwise about the leading tone, but it’s not the furthest that one of our chords has to travel before reaching the tonic; that distinction can go to the next and final chord.

Subdominant

As the prefix in its name suggests, the subdominant is located a perfect 5th below the tonic. It’s not related to the tonic in the same way the other chords are. While we could say that all the other chords belong to the tonic key, we could not say that about the subdominant. It would be much more accurate to say that the tonic belongs to the subdominant key instead. We’ll get into more detail about that in the future, but even looking at where the subdominant falls on the circle of 5ths should begin to raise some questions as to how it fits in with the others.

subdominant

After falling to the subdominant, then its straight across to the leading tone to continue the descent of perfect 5ths  that eventually resolves back to the tonic one last time. And it’s worth mentioning now that just as the mediant lies in between the dominant and tonic, so to does the submediant to the tonic and the subdominant.

subdominant progression

Conclussion

Everything we’ve done here can and should be learned for all the other major keys. We tend to think that ‘C’ always has to be at the top of the circle of 5ths, but to help in visualizing these progressions it might be a good idea to draw the circle of 5ths with other notes in the upper most position instead.

Like I mentioned at the beginning of this post, understanding this concept is the key to understanding more complex progressions and modulations. In other words, this is not the only way to get around the circle of 5ths.

7 comments

  1. Wow. Some really good thoughts here. Many of these things I knew before, but this is a fresh (at least to me) way to present this information. Definitely easy to grasp, perhaps even for my high school kids. The previous post is well, also.

    Looking forward to the rest of the series! Cheers.

    1. Thank you for reading and for the comment.

      Yes, the subdominant is somewhat of an anomaly. Western music uses letter-names in regards to pitch, which simplifies an otherwise complex system in a manner that is largely misleading; I intend to elaborate more on this soon.

      I recommend the book Harmonic Experience by W. A. Mathieu for a good way to start looking beyond any general assumptions.

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