What Is a Tritone? The "Devil's Interval," Explained by Ear

The interval people nicknamed the devil

Somewhere along the way, one interval picked up a reputation no other interval can match. Medieval theorists called it diabolus in musica, the devil in music, and the nickname stuck for centuries. People still repeat the story that the Church outright banned it.

The truth is a little less dramatic and a lot more useful. So here is the plain answer, plus the part the dry theory pages skip: what a tritone actually sounds like, and how to hear it for yourself.

So what is a tritone, exactly?

A tritone is the interval made of three whole tones stacked on top of each other. That is where the name comes from: tri (three) plus tone. Three whole steps, no shortcuts.

If you measure it in semitones, that is six. Six semitones lands you exactly halfway across the octave, which is part of what makes this interval feel so strange. It splits the octave perfectly in half, and no other interval does that.

The same distance has two names depending on how you spell it. Going up, C to F sharp is an augmented fourth. Coming the other way, C to G flat is a diminished fifth. Same six semitones, same sound, two different labels. If you have seen those two terms and assumed they were different things, they are not. They are the tritone wearing two hats.

That is the whole tritone definition in one breath: three whole tones, six semitones, an augmented fourth or a diminished fifth, sitting dead center in the octave. If intervals are new to you, it is worth starting with what an interval is before going deeper here, because the tritone interval makes more sense once you can place it among its neighbors.

Why is it called the "devil's interval"?

Here is where the devil's interval legend needs an honest correction.

The phrase diabolus in musica is real, and the unease around the interval is real too. Medieval and Renaissance musicians genuinely found it awkward. It was hard to sing in tune, it clashed with the smooth, consonant sound their counterpoint aimed for, and it refused to sit still. Voice leading rules of the era steered singers around it.

But the popular internet version, that the Church formally banned the tritone and threatened anyone who played it, does not hold up. There is no edict, no inquisition for the augmented fourth. What existed was a strong stylistic preference that treated the interval as something to handle carefully, not a crime. Calling it "the devil in music" was a memorable way to teach students that this interval was dissonant and needed resolving, not a literal accusation of heresy.

So the reputation is half folklore, half real acoustics. Strip away the myth and you are left with the part that matters: the tritone is restless. It sounds unstable, suspended, like it is leaning toward something it has not reached yet. That tension is the whole point, and it is exactly what you can learn to hear.

What a tritone actually sounds like

Describing a sound in words only gets you so far, so let me hand you songs you already know.

The cleanest example is "Maria" from West Side Story. When Tony sings the name, the leap from "Ma" up to "ri" is an ascending tritone. Bernstein chose it on purpose. It sounds yearning and unresolved, which is the point of the whole song.

The Simpsons theme opens the same way. Sing the words "The Simp-" and the jump from "The" to "Simp" is an ascending tritone. Danny Elfman wanted something that felt a little off and playful, and the tritone delivers it.

For the heavy version, listen to the opening riff of Black Sabbath's song "Black Sabbath." That slow, ominous figure leaning on the tritone is most of what makes early doom metal sound like a storm rolling in.

And if you want the everyday version, listen to a two-tone emergency siren or the low, dread-building stab a film score uses when something is about to go wrong. That sense of alarm is the tritone doing its job.

Notice what all four have in common: tension. Suspense. A feeling that something has to move next. That is the sound you are learning to recognize.

Where the tritone shows up in real music

Here is the shift from spooky trivia to practical reality. You do not just bump into the tritone in a few famous riffs. You hear it constantly, often without naming it.

The most important place is the dominant 7th chord. Take a G7 chord: G, B, D, F. Look at the B and the F. That is a tritone, sitting right inside one of the most common chords in all of Western music. That tritone is the engine of the chord's tension. It is what makes a V chord pull so hard back toward the I, the sense of "this needs to resolve home." Every time a song lands on a satisfying ending, a tritone resolving is usually doing the work underneath.

Blues and jazz lean on this constantly. Dominant 7th chords are everywhere in both, so the tritone is baked into the genre's color, not hidden as an accident. Jazz players take it further with a move called tritone substitution, swapping one dominant chord for another a tritone away because they share that same restless pair of notes. That is a deeper rabbit hole than this page needs, but it is worth knowing the tritone is the reason the trick works at all.

The bigger idea sits underneath all of it: tension and resolution. The interval that sounds "wrong" on its own is exactly what makes the resolution feel right. Without the lean of the tritone, the arrival home would not feel like much of an arrival. The dissonance is not a flaw to avoid. It is the setup for the payoff.

How to train your ear to hear it

Recognizing a song is recall. Recognizing the interval cold is the actual skill, and the two are not the same. Plenty of people can sing the start of "Maria" and still freeze when a tritone shows up out of context.

So here is a simple path. Start with your anchor song and sing the leap until it is automatic. Then make it harder on yourself: have something play a tritone with no melody attached and try to name it before you think. The goal is to move from "that reminds me of Maria" to "that is a tritone" without the detour through the song.

The catch is the tritone rarely fools you on its own. It trips you up when it sits next to a perfect fourth or a perfect fifth, its close neighbors. That is where comparison practice earns its keep. Coco's Span game has you tell two intervals apart by ear, which is exactly how you learn to separate the tritone from the intervals it gets confused with. And since the Maria and Simpsons leaps are both ascending, drilling ascending intervals in Climb lets you hear the tritone rise the same way those melodies do.

If you want the broader method rather than just this one interval, how to recognize any interval by ear walks through the approach, and the interval ear-training path lays out where the tritone fits among the rest.

One honest note on practice. Short and consistent beats long and occasional, every time. Five focused minutes a day, aimed squarely at the interval you keep missing, will outrun an hour-long cram session you do once and forget. Train the thing you get wrong, not the thing you already know.

A note worth keeping

The "devil's interval" is not cursed and it was never really banned. It is just the most restless interval in the octave, the one that splits everything down the middle and refuses to settle.

The strange part is what happens once you can hear it. It stops being a piece of trivia and starts showing up everywhere: in the chord that resolves a pop song, in a siren three streets over, in the riff that gave metal its menace. The devil, it turns out, has been hiding in plain sound the whole time. Go find it.