Few sounds in music carry as much historical baggage as the tritone. Banned by medieval monks, embraced by jazz musicians, and wielded like a weapon by heavy metal guitarists, this single interval has had one of the most colorful journeys in all of music theory. But beyond the mythology, the tritone is a profoundly important building block of Western harmony. Understanding it will change how you hear chord progressions, resolve tension, and navigate complex music.
What is a tritone exactly?
A tritone is an interval spanning three whole tones, or six semitones — exactly halfway through the octave. From C it lands on F#/Gb. It can be spelled as an augmented 4th (C to F#, which wants to expand outward) or a diminished 5th (C to Gb, which wants to contract inward). The tritone is its own inversion — no other interval does that.
The tritone can be spelled as either an augmented fourth (C to F#) or a diminished fifth (C to Gb). Enharmonically, these are the same pitch on a piano, but they carry different harmonic implications depending on context. An augmented fourth wants to expand outward; a diminished fifth wants to contract inward. This dual identity is part of what makes the tritone so versatile.
One peculiar property: the tritone is its own inversion. If you flip C-F# upside down, you get F#-C, which is still a tritone. No other interval does this. It sits at the exact midpoint of the octave, a kind of harmonic fulcrum.
Why is the tritone called the devil’s interval?
The nickname diabolus in musica comes from medieval music theory. The tritone resisted neat mathematical ratios, was hard to sing in tune, and created unresolved tension that clashed with the spiritual goals of sacred plainchant. Whether any pope literally declared it satanic is debatable, but the discomfort was real, and the name stuck.
Medieval music theory, rooted in the teachings of Guido of Arezzo and later theorists, was built on a system of consonant intervals: octaves, fifths, and fourths. The tritone, which resisted neat mathematical ratios, was genuinely avoided in composition and vocal training. It was difficult to sing in tune, and in the modal system of plainchant, it created unresolved tension that clashed with the spiritual goals of sacred music.
Whether any pope literally declared it satanic is debatable, but the discomfort was real. The interval was considered unstable and problematic, which is why counterpoint rules from the Renaissance onward specifically addressed how to handle it. The name stuck, and centuries later it became a badge of honor for composers who wanted to evoke darkness, tension, or rebellion.
Why does the tritone sound so dissonant?
From a physics standpoint, consonant intervals have simple frequency ratios (octave 2:1, fifth 3:2, fourth 4:3). The tritone’s ratio is approximately 45:32 (or irrational √2 in equal temperament) — the waveforms rarely align, and your ear perceives the misalignment as roughness. But dissonance creates expectation, and expectation is what drives functional harmony.
But dissonance is not the same as unpleasantness. Dissonance creates expectation. When you hear a tritone, your ear demands resolution. That demand is what drives music forward, and it is why the tritone sits at the heart of functional harmony.
How does the tritone work inside dominant 7th chords?
Every dominant 7th chord contains a tritone between its 3rd and 7th. In G7 (G-B-D-F), B to F is a tritone. This internal tritone is the engine of the chord’s tension. When G7 resolves to C: B moves up a half step to C, F moves down a half step to E. The dissonance contracts to consonance — that’s the V-I cadence.
Take G7: G - B - D - F. The interval from B to F is a tritone (three whole tones: B-C#-D#-F, or simply six semitones). This internal tritone is the engine of the chord’s tension. It is what makes G7 feel like it absolutely must resolve to C major.
When G7 resolves to C, the tritone resolves by contrary motion:
- B (the third of G7) moves up a half step to C
- F (the seventh of G7) moves down a half step to E
The dissonance contracts to a consonance. That half-step movement in both voices is what gives the V-I cadence its satisfying, inevitable quality. Without the tritone, dominant chords would lose their gravitational pull.
What is tritone substitution in jazz?
Two dominant 7th chords a tritone apart share the same tritone. G7 contains B-F; Db7 also contains F-Cb (enharmonically F-B). So you can substitute Db7 for G7 when resolving to C major — Dm7-Db7-Cmaj7 instead of Dm7-G7-Cmaj7. The bass moves chromatically (D-Db-C), but the critical tritone still pulls to C and E.
This means you can substitute Db7 for G7 when resolving to C major. Instead of the standard ii-V-I (Dm7 - G7 - Cmaj7), you get Dm7 - Db7 - Cmaj7. The bass line now moves chromatically: D - Db - C. The resolution still works because the critical tritone (B and F) is still present, still pulling toward C and E.
Tritone substitution is one of the defining sounds of bebop and modern jazz harmony. It creates chromatic bass movement, richer voice leading, and a sophisticated harmonic palette. Once you learn to hear it, you will recognize it everywhere in the playing of artists like Charlie Parker, Thelonious Monk, and John Coltrane.
Why is the tritone foundational to metal and rock?
The tritone is a foundational metal sound because of its abrasive, unstable character. Black Sabbath’s self-titled song opens with an exposed tritone (G to Db), deliberately chosen to evoke dread. Metal guitarists play it with heavy distortion to maximize tension — defining thrash, death, and progressive metal. Film composers use it for the same reasons: danger, the supernatural, psychological unease.
On the opposite end of the spectrum, the tritone is a foundational sound in heavy metal and hard rock. The opening riff of Black Sabbath’s self-titled song is built on an exposed tritone (G to Db), and the dissonance was deliberately chosen to create a feeling of dread.
Metal guitarists use the tritone (often called a “flat five” in that context) as a power interval, playing it with heavy distortion to maximize its abrasive quality. Thrash metal, death metal, and progressive metal all lean on tritone-based riffs to create tension, aggression, and an unsettled feeling that defines the genre.
The interval also shows up in film scoring for the same reasons. Whenever a composer wants to signal danger, the supernatural, or psychological unease, the tritone is often the first tool they reach for.
Where else does the tritone appear in everyday music?
In Lydian mode (raised 4th creates a tritone from the root — gives Lydian its bright floating quality, used by film composer John Williams for wonder and adventure). In the blues scale (the b5 “blue note” — the heart of blues expressiveness). In diminished triads (root to 5th is a tritone). It’s quietly everywhere in tonal music.
The Lydian Mode
The Lydian mode (the fourth mode of the major scale) features a raised fourth, creating a tritone between the root and the #4. In C Lydian (C - D - E - F# - G - A - B), the C to F# tritone gives the mode its bright, floating, almost magical quality. Film composer John Williams uses Lydian extensively for themes of wonder and adventure.
The Blues Scale
The blues scale (1 - b3 - 4 - b5 - 5 - b7) places the tritone (the b5, also called the “blue note”) at the center of its sound. That note, hovering between the fourth and fifth, is what gives blues its characteristic tension and expressiveness.
Diminished Chords
A diminished triad is built entirely from minor thirds, and it contains a tritone between its root and fifth. Bdim (B - D - F) has the same tritone as G7. This is why diminished chords often function as dominant substitutes and passing chords.
How do you train your ear to recognize tritones?
Use the reference “Maria” from West Side Story (ascending augmented 4th). Play any note, then six semitones above it on your instrument — listen to the tension, then resolve each note by half step in contrary motion. Isolate the B and F inside G7. Listen for it within any dominant chord pulling to resolution.
- Sing it. The opening interval of “Maria” from West Side Story is a tritone (ascending augmented fourth). Use this reference to internalize the sound.
- Play it on your instrument. Pick any note and play the note six semitones above it. Listen to the tension. Then resolve each note by half step in contrary motion.
- Find it in dominant chords. Play a G7 chord and isolate the B and F. Hear how those two notes create the chord’s restless energy.
- Listen for it in context. When you hear a song that feels like it is about to resolve, listen for the tritone within the dominant chord pulling toward the tonic.
Ready to sharpen your interval recognition skills? Music Genius includes Pitch ID — dedicated ear-training exercises where you practice identifying tritones and every other interval by ear. Pair with Music Intervals Guide and Seventh Chords Explained to go deeper on the harmonic context.
Frequently Asked Questions
What is a tritone in music?
A tritone is an interval spanning three whole tones, or six semitones — exactly halfway through the octave. From C, a tritone lands on F# or Gb. It can be spelled as an augmented 4th (C to F#) or a diminished 5th (C to Gb). Enharmonically the same pitch, these spellings carry different harmonic implications.
Why is the tritone called the devil's interval?
The nickname diabolus in musica ('the devil in music') comes from medieval music theory. The tritone resisted neat mathematical ratios, was difficult to sing in tune, and created unresolved tension that clashed with the spiritual goals of sacred plainchant. Whether any pope literally banned it is debatable, but the discomfort was real — counterpoint rules from the Renaissance specifically addressed how to handle it.
Why does the tritone sound dissonant?
Consonant intervals have simple frequency ratios (octave 2:1, perfect 5th 3:2). The tritone's ratio is approximately 45:32 (or the irrational √2 in equal temperament), so the waveforms rarely align — your ear perceives this misalignment as roughness or tension. But dissonance creates expectation, which is what drives functional harmony.
What role does the tritone play in dominant 7th chords?
Every dominant 7th chord contains a tritone between its 3rd and 7th. In G7 (G-B-D-F), B to F is a tritone. This internal tritone is the engine of the chord's tension — it's what makes G7 feel like it must resolve to C major. When G7 resolves: B moves up a half step to C, F moves down a half step to E. The dissonance contracts to consonance.
What is tritone substitution in jazz?
Two dominant 7th chords a tritone apart share the same tritone. G7 contains B-F; Db7 also contains F-B (enharmonically the same). You can substitute Db7 for G7 when resolving to C major — Dm7-Db7-Cmaj7 instead of Dm7-G7-Cmaj7. The bass moves chromatically (D-Db-C) but the critical tritone still pulls to C and E.
Why do metal bands use the tritone?
The tritone is a foundational sound in metal because of its abrasive, unstable character. The opening riff of Black Sabbath's self-titled song is built on an exposed tritone (G to Db), deliberately chosen to evoke dread. Metal guitarists play the tritone (often called 'flat five') with heavy distortion to maximize its tension — defining thrash, death, and progressive metal.
Where else does the tritone appear in music?
Inside dominant 7th chords (and the V-I cadence they create). In the Lydian mode (raised 4th creates a tritone between root and #4 — film composer John Williams uses it constantly for wonder). In the blues scale (the b5 'blue note'). In diminished triads (the b5 is a tritone from the root). It's quietly everywhere in tonal music.
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