Mediants in Music - A Powerful Tool

The term mediant refers to the third scale-step above and below your point of reference. If we started on the tonic, then scale steps three and six (that's three scale steps down from the tonic) become your mediants. Usually, a major triad has two minor triads as mediants and the other way around. Mediants are easy-to-use yet powerful building blocks in composition as they can reinforce a tonal center or even modulate to new ones.

Mediants in Scale-Step Theory

Mediants have a secure musical connection to their tonic, which they orbit around. As usual, we want to start things off efficiently and practically. So, let's have a look at the C major scale and write out the triads on top of the scale tones.

Don't be confused that we spread the scale over two octaves. In the next step, we'll need to go down from the tonic so that you can see the relation in scale-steps more quickly, and therefore, we've included two octaves.

Let's make the tonic our point of reference for the moment. We are going to change this later in this article, but we want you to understand the intervallic relation before we move further. Mediants live in a distance of a Diatonic third above and below the tonic. We can see very quickly that we end up getting an A minor and an E minor triad if we started on C tonic.

Let's filter out all the other scale steps that we are not using for now. If we played the tonic and its two related mediants alternately, then it becomes clear that we have to change one tone at a time to make the transition from the tonic to a mediant and back. In other words, two tones remain the same and don't move at all.

That's a strong musical connection right here! Look at the graphic below, which shows how to voice-lead between the tonic and the mediants.

Mediants on the Circle of Fifths

You realized that we said the "RC5 gives us all the information we need to define a tonal center and its mediants", right? Well, this is not generally true but conditional. The relative minor key works as long as we build a major triad on the tonic of the connected major key. But what happens if we picked a minor triad instead?

Major and Minor Mediants

Let's leave the RC5 for now and come back to a concept that we also mentioned already: "We have to change only one scale tone in our original triad to turn it into a mediant structure"!

Starting from a major triad, we either moved scale tone five up to six or the root down to scale tone seven. That's a universal concept and will work with minor triads the same way. So, let's put it to the test and see what we'll get.

To keep things simple for the moment, we want to limit the mediant structures to plain major or minor triads. That means that we want to avoid augmented or diminished triads for the moment. So, if we started in C minor, the most apparent chords that we can create by changing the exact scale tones that we did in major are Ab major and Eb major.

Let's have a closer look at what we just did here. Starting from major, we moved the top note two chromatic steps up or the bottom note one step down.

In minor, we did the same movements, but in the opposite direction. The high note moves up one chromatic step, and the root note walks down two steps. In the picture below, you can see how major and minor complement each other via reflection.

It might not feel as such, but we are knee-deep in Interval Theory already. For the future, you want to remember that major and minor triads are reflections of one and another - this is also true for their mediants as they originate from their mother triads.

Creating Mediants via Formula Extension

Let's explore the power of Interval Theory even a bit more, and for that, we want to get rid of any scale or musical key for now. Let's regard the triads as abstract vertical structures and describe them via the distances in chromatic steps from bottom to top.

This all results in a major triad being a 4+3 and minor one being a 3+4 (when we start on the root tone of each triad). The picture below shows how we get to these numbers.

When starting from the root tone, triads always consist of those building blocks of 3s and 4s. That is equally true for major and minor.

If we used these two numbers to create a more extended sequence that alternates between 3s and 4s, we get to the mediants naturally. This might sound very complex to you at first, but let me explain what that means, and you'll recognize how simple the concept is.

And yes, it works the same way if we started on a minor triad instead.

This method lets you pick your mediants to any triad very quickly - no matter the scale, the root, even the tone, or the musical key! Actually, it provides a lot of freedom in composition. You just want to focus on the distances between the notes in chromatic steps, and you'll automatically get to the correct pitches!

Using Mediants to Modulate

As long as you stick to the nearby mediants, your tonal center will remain stable and robust. You might already know that, in Interval Theory, every root tone can act as a temporary tonal center, no matter the key. That's exactly how we want to use mediants to modulate to other tonal centers.

Start on any triad and construct the mediants around it (using whatever method works for you). Let's make one of those orbiting triads our new point of reference so that we can create another set of mediants on it and so on.

Slowly but surely, we will move through all of the 12 tones available to us; and you can stop that sequence at any point.

The reason why this method works so smoothly is that we always change only one note a time. It's quite simple for the audience to follow the progressions as two tones can be held over into the following chord. But the truth is that you can use this process to modulate to ANY tonal center. Let's have a listen to the following example.

And you don't even have to write out the entire progression because we can see the result already on the Circle of Fifths! Every other step in this sequence creates a plagal cadence and equals one step on the RC5. It's almost like we've created a more detailed version of the Circle of Fifths. Here's the same example like above but this time, the steps from the RC5 are highlighted.

Showing the Mediants in Action

We've reached the moment where we want to get into some actual music. Now that we know a bit of theory behind mediants and how to construct them, let's hear how they sound in a musical context.

As usual, let's start nicely and slowly by writing out a quick sketch based on the methods explained in this article. Why don't we begin this musical adventure on a D minor triad and go down in a mediant-relation?

You can clearly see how the distances between the triad root tones alternate between 4s and 3s. Actually, below we are looking at a sketch that was written by Alex Gostin. He is a member of our Academy and a fantastic composer from Australia.

We think that showing actual results from members is very precious and gives a transparent picture of what happens inside the Academy. It's not the theory that connects people, but the music that comes out of it.

Alex could have continued this pattern forever, and it would have sounded great. But he decided to get out of it by breaking the alternating pattern after the Bb minor triad when he moved into the final G major chord.

Again, this was just his starting point. Now, let's add more complexity to the sketch before we go into the orchestration. Whenever you work with triads, don't forget that substitute tones are right around the corner and available at all times! They can add a bit of color vertically (by bringing in some of the higher overtones) and also some horizontal movement. Here are the most common scale-tone substitutions that you can instantly use to spice up your sketch.

And here's how Alex modified his sketch using substitute tones. The benefit of using the Formula Extension is that the progression always sounds very musical, and it frees you from the limitations of sticking to a key - you really get the best from both worlds, the Diatonic system, and Interval Theory.

Next, let's have a listen to the orchestrated version of that sketch in the video below. Alex did an excellent job using the brass section to generate power and a heroic feel. Also, the strings reinforce the progression and even raise the energy level by bringing in a motor.

It's fascinating how Alex moved from a D minor (that was his starting point) to the G major triad at the end using all of these mediants. He simply could have gone from D to G directly, but instead, he decided to take the listener on a much more adventurous journey through harmony.

That's a brilliant demonstration of how to turn a basic authentic cadence into something way more sophisticated. And on top of the musical aspect, that's also a great technique of how you can expand two bars of music into eight (without putting any creative pressure on yourself).

A word of Inspiration

Now that we know how major and minor mediants line up, try to interchange all of the mediants to the same tonic. You'll be surprised about the harmonic changes and emotional shifts that you can create this way.

In the Diatonic system, those changes are rather complicated to explain as you'll have to leave the scale and maybe even your tonal center, but as long as you stick to your (imaginary) tonic, be aware that all the mediants exist. This point of view will help you to simplify your decision-making and lead you to new musical places that are not easy to find by sticking to Diatonic thinking.

Summary

Whenever you come across simple triads in your chord progressions, never forget that their mediant structures are also available. You can use those to either reinforce your current tonal center or to modulate to new musical places. It's your decision, and it comes down to the musical story that you want to tell. Just as a quick summary, here's what we've covered in this article.