Music Theory: The Tritone

Ever heard a sound in music almost too gruesome to bear? Or been haunted by a disturbing harmony in a horror movie? Chances are you have been made the victim of what is commonly referred to as “the devil’s interval”—the tritone.

The tritone is built of two notes six half steps apart (you can also think of this as three whole steps). The tritone is unique in a number of ways, not least of which is that it is scientifically the worst sounding simple interval. When a tritone sounds, the unique soundwaves of each note collide chaotically to create what we call “beating.” Other intervals, such as the perfect fourth, create soundwaves that line up more seamlessly to create a pleasant sound with less beating. We call these pleasant intervals with less beating “consonant” and unpleasant intervals with more beating “dissonant.”

Another curiosity of the tritone is its symmetry. The tritone is the only interval that inverts to itself. For instance, C and F# form a tritone when C is on the bottom. Any other interval would change if we moved C to be above F# on the top of the interval (this is called inversion, which we’ll cover later); however, we can count and find that the distance is the same, whether C is on the bottom or the top. From this, we can also realize that the tritone is the halfway point of the octave. If we had two Cs and wanted to find the middle of that octave, we would end up finding F#—the tritone.

You may be wondering why we would ever need to know about such a disgusting sound. When could this possibly come in handy? Well, hold your horses. Whether you know it or not, tritones are found all over popular music. Chances are they show up more than once in your favorite songs. The reason for that is a little beyond us at the moment, but consider a few general examples: In the blues, tritones are a foundational part of every single chord, giving them the crunchy tension that makes the blues so compelling; rock and roll (being a descendant of the blues) utilizes tritones heavily as well; you can even find tritones in whatever fresh pop album drop you’re listening to. In short, tritones are a universal source of tension that all musicians use to manipulate the emotions of their music.

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So far as listening examples go, there are only two melodic examples of tritones that are commonly referenced (remember, tritones are primarily found in harmony rather than melody). For you Simpsons fans out there, listen to the theme song closely… you’ll find a tritone between “The” and the first syllable of “Simpsons.” If you don’t watch the Simpsons, then perchance you’ll take better to a musical theater example (because that logic is flawless); harken back to West Side Story’s glory days and sing a bit of the hit song “Maria.” In fact, don’t even finish singing her name; the tritone lives between “Ma” and “ri.” Happy singing!

Reference Chart for Interval Ear Training

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