What you need to know about 13s

13s are unique - that's one octave and one half-step. It can stick out very quickly in compositions but also provides many opportunities. It's essential to know its unique character to use it most efficiently. It's time for dissonance!

Note: Please note that there are many musical demonstrations in the audio version of this episode, which are not accessible in the transcript.

13 - The Special Interval

Today, I want to talk about an extraordinary interval. I know this sounds like not all the intervals are unique, but one of them really sticks out a bit more and needs some special treatment in composition and orchestration.

It's interval 13. That's one octave and a half-step or, in short, 13 half-steps. Now, what makes this interval unique, and why should we treat it more carefully?

Well, let's not dance around but cut to the chase directly. The short answer is that it's not part of the Overtone series, and therefore, it sticks out easily and grabs the listener's attention because of its dissonant sound. I want to share a quick insight with you.

At the Academy, we often refer to this interval as the "producer's interval". Usually, producers care the most about making a product as good and valuable as possible since this maximizes their ROI, the return on investment. Anyway, most producers I've come across so far have not been very gifted musically, no offense intended. Still, one thing that every producer could catch quickly was interval 13!

Again, it's not a natural interval from the Overtone Series. So, it doesn't appear to the fundamental. That's why we're calling it the "producer's interval" as well, as even non-musical producers recognize it. So, before we go any further, let me play you this interval on the piano. First, we'll listen to a C note, then the Db one octave above, and then both tones together. Watch out for the dissonance.

Using the Dissonance in Composition

The question is: "How should we treat this interval in composition then?" Should we simply avoid it? It depends on the context, and I want to give you two different scenarios that practically show when it works and when it doesn't.

1st Situation - Line Writing

Let's talk about line writing. Whenever you have several lines or melodies that weave together, you want to watch out for 13s vertically. For singers, they are tough to intonate, and it probably won't sound good - so, before everybody blames the composer because the piece sounds weird.

Just try to catch those 13s beforehand and compensate for them. However, there's one exception to this guideline, and that is very strong lines. The moment your melodies make perfect sense on their own, the horizontal force becomes more robust and even stronger than the vertical connection to other parts. And that all is just based on how we perceive music. We can produce monophonic lines very easily using our voice, and that's why our brain is more interested in remembering lines in general.

So, before we look at the second scenario, I want to give you some concrete action steps.

1 - Pick a scale and a root tone.
2 -
Write a melody in your singable register.
3 -
Just follow scale tones for now, and don't write more than eight bars in total.
4 -
Write a second line below it, using a different rhythm and other scale tones.

So now, you have two independent lines moving against each other. Check the vertical distances between the notes and check for 13s. Actually, the chances are high that you'll hear them right away, but if you don't, go through the notes one at a time and check the vertical distances between the lines. You can even bring in a few 13s purposely, just for the fun of it, so you'll get to hear them.

If you've never done a quick test like that before, please do yourself a favor and try it right now or at least today.

Here's even a pro tip for you:
Don't let this "producer's interval"-thing mislead you. If the context allows for dissonance, 13s can be lovely and even very practical. Try to imagine a soundtrack for a thriller or horror movie without any dissonance. It just doesn't feel right as the given context asks for a particular sound palette.

So, the solution is not to altogether avoid it but to become aware of it.

2nd Situation - Chords

The second scenario describes a different context, and that is harmony. If you are familiar with Jazz theory, then I'm pretty sure you've used a flat ninth chord in your writing already. And even if you've never heard the term "flat ninth chord", don't worry. Let's make it concrete and pick C as our root tone. A flat ninth chord over C would give you the tones: E, G, Bb, and Db - those are the following chord tones to the C root: 3, 5, -7, and -9.

This doesn't sound bad, actually, but let me quickly remind you about that 13. The moment we remove the harmony tones, the dissonance becomes more obvious again.

It works as a chord, though. And that's just because of scale tone -7 in that structure. Although interval 13 does not appear in the Overtone series, we can create a proper musical context that embraces that sound. It even can resolve very naturally.

Generally speaking, dissonance equals instability, and we can use this instability for musical storytelling - make it part of your storyline and guide your audience through the story elegantly.

So, harmony embraces this interval. It can bring some nice colors to the palette.

Pro-Tip for Interval Theory:
Let's bring in more intervallic thinking and see how we can connect a 13 to other intervals. Every isolated interval can appear in two positions. I know that might need a second to sink in.

The 13 exceeds the octave, right? So, what happens when we bring down the Db one octave? Well, it creates a 1-interval against the C below. And if we took the C note and put it up one octave, we get an 11-interval.

Don't get confused with those numbers. It's actually all the same interval but played in closed harmony, that's within the octave, and in open harmony, that's more than the octave. In simple words, 1s, 11s, and 13s are the same and share similar qualities and musical connections. They are all connected and offer great musical opportunities to the composer.


This was quite a bit of information. That's why I want to give you a quick summary. 13s can become a disturbing factor in tonal line writing. They can stick out and grab the audience's attention in the wrong way because of their dissonance.

Now, if that's something that fits into the context, fantastic, just be aware of it.

13s work nicely as flat ninth chords in those jazzy progressions. So, 13s can add dissonance or spice and offer a tonal resolution simultaneously.

In conclusion, I suggest you pay some attention to 13s in your writing and make a conscious decision about whether or not you want to use them in a given context. They can work very elegantly and enhance your musical storytelling.

I hope you enjoyed this episode, and I'm already looking forward to welcoming you back quite soon.


Take your time and play around with interval 13 on your preferred instrument. Put the two situations described in this episode to the test and see how you can make it work in your compositions.

Author: Frank Herrlinger