If there’s one interval in music theory with a reputation, it’s the tritone. Sometimes called “the devil’s interval”, this strange, tense sound has fascinated (and unsettled) musicians for centuries. But what is a tritone? How do you recognise it? And why is it such a powerful tool for composers, songwriters and improvisers?
Let’s break it down - step by step. With real-world examples to spark your ears and plenty of tips for using it in your own music. Ready to dive in?
At its core, a tritone is a musical interval spanning three whole tones (hence the name). On a piano, that means six semitones from your starting note and rests in between a perfect fourth and a perfect fifth.
Try this with just the white notes: play a F, then hit an B. Hear that uneasy, restless sound? That’s a tritone - F to B is six semitones apart, which makes it a tritone.
In classical music, it’s also called:
Same sound, two names. You’ll see both in sheet music depending on the harmonic context.
But here’s the thing: the tritone doesn’t just sound unusual. It feels unusual. There’s an inherent tension in this interval that almost begs to be resolved. Which is why it can be found in songs throughout musical history.
There’s a reason people once called it diabolus in musica (“the devil in music”). In the Middle Ages, tritones were considered too dissonant for sacred music and were limited by the laws of counterpoint. Some even claimed composers were banned from using them. Truthfully, this was likely exaggerated - but it makes a great story. When the era of Baroque and Classical music arrived, many composers accepted the tritone into their musical compositions, using it in more controlled ways then you may hear in musical eras to come.
Now technically speaking, the dissonance comes from the tritone’s position right in the middle of the octave. It splits the octave perfectly in half, creating a symmetrical, ambiguous sound. Your ear can’t easily tell whether it wants to resolve up or down. That ambiguity creates a delicious musical tension.
Once composers realised the tritone’s power, they ran with it. You’ll hear it everywhere in western music and beyond - from classical masterpieces to metal riffs and jazz standards. And it’s not limited to those genres either. Use of the tritone can often creep into film scores - especially horror and thriller soundtracks - adding an eerie, spine-tingling quality. You’ll also find them in blues turnarounds and even pop music, where they’re used for a splash of drama or surprise.
Here are some iconic examples to train your ear:
Maria – West Side Story (Leonard Bernstein) The first three notes of Maria outline a simple but effective shape:
the tonic (1), the tritone (#4), and the perfect fifth (5).
The leap to the tritone creates tension, which resolves immediately on the fifth. This gives the melody a sense of lift and drama that matches the emotion of the song.
Purple Haze – Jimi Hendrix The opening guitar riff uses a tritone to create that signature edgy vibe. It’s a classic example of how rock musicians embraced the interval’s rebellious energy.
Black Sabbath – Black Sabbath The ominous tritone in the main riff defined the sound of heavy metal. Tony Iommi leaned into its “evil” reputation, and it worked.
Jazz standards and tritone substitutions Tritone substitutions are a hallmark of jazz harmony. They work by replacing a dominant chord with another dominant chord a tritone away. Both chords share the same tritone interval internally, so the substitution creates smooth voice leading and adds chromatic interest to a progression. For example, in Dream A Little Dream Of Me, you’ll hear tritone subs (Cmaj7 to E♭ instead of A) creating unexpected chord progressions that feel both sophisticated and tasteful.
You don’t need to be a music theory expert to start playing around with tritones. Let’s break it down step by step:
The tonic is the “home” chord of a key - the one everything feels like it wants to return to (like C major if you’re in the key of C).The dominant is the chord built on the fifth note of the scale (like G in the key of C), and it naturally creates tension that wants to pull back to the tonic.
Spot them in chords.Take a dominant seventh chord - like G7. Inside that chord, there’s a tritone between the third and seventh notes. That’s the secret sauce that makes it sound tense and ready to resolve back to the tonic chord (C major in this case).
Try a tritone substitution.Here’s a fun one: swap a dominant chord with another dominant chord that’s a tritone away. So instead of G7, you’d play Db7. It still leads back to C, but with a cooler, jazzier twist.
Add tension to melodies.Want your melody to sound dramatic or unexpected? Try jumping between two notes that are a tritone apart. It’s a bold move that grabs attention.
And remember: the best way to really hear and feel what a tritone does is to practise it. Get hands-on and let your ears lead the way.
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The tritone may have a spooky nickname, but it’s nothing to fear. In fact, it’s one of the most expressive tools in music. Learn to hear it and use it - and you’ll open up a whole new palette of emotional possibilities in your music.
Remember: theory isn’t just about rules. It’s about freedom. And with a little practice (the fun kind), you’ll be bending the “devil’s interval” to your will.
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