The tritone offers a unique opportunity for songwriters. While possibly not as attractive as other more “consonant” intervals like major or minor thirds, perfect fourths, fifths, or major sixths, the tritone (aka augmented fourth or diminished fifth) is ubiquitous in popular music.

There are numerous examples of tritones in music, television, and movie themes. For example, the theme from South Park is littered with tritones in the guitar riff. The main theme from the Simpsons prominently features a tritone. The famous prog-rock band Rush also uses the tritone in their hit “YYZ.”

You rarely hear a tritone stand alone in contemporary pop, but it is immediately recognizable when you do. More frequently, you find tritones hidden inside a chord progression. Every dominant seventh chord (C7 or F7, for example) contains a tritone interval between the 3rd and ♭7th degrees of the chord. The blues scale includes a tritone interval, and there are many examples of major chords with tritones as well. The tritone is a multi-purpose interval, with many more dimensions than its devilish reputation might suggest.

What exactly is a Tritone?

What exactly is a tritone? Good question! A tritone is an interval equal to six half-steps. Remember that an interval is the distance between any two notes. We measure intervals in half-steps (or semitones). To get up to speed on reading sheet music you might want to check out this article we wrote on the topic.

One half-step is the distance from one note to the next. For example, C to D♭ is one half-step, E to F is one half-step, and G to G♯ is one half-step. Here are some examples of tritones on the staff:

Inside of every major scale, there is one naturally occurring tritone between the 4th and 7th degrees of the scale:
The tritone is also the even division of the octave. Remember, there are 12 notes in equal temperament and 12 notes inside of one octave. Furthermore, the interval of 6 semitones evenly divides the octave into two pieces. Crazy, right?

You can verify this for yourself on the circle of fifths. Take our previous examples, C to F♯, E to B♭, G to D♭, and B to F, and locate their positions on the circle. You will find they are exactly opposite one another.

If you just play these two tones together, you might find the sound unpleasant and somewhat unstable. You might feel like the tones want to pull to a more complete resolution point. This insight gives us a clue about its uses and why its history.

That Interval is a Devil!

Despite its benign nature, the tritone has a dubious history in Western music. If we travel back in time to the Middle Ages, we will find that the Church primarily controls the music in Europe. Most people’s lives revolved around their religious faith. The Catholic Church made a serious effort to spread itself throughout Europe via a unified form of music, known today as Gregorian chant after Pope Gregory. One result of this effort was that most people experienced music primarily at Church, and the Church employed many musicians to compose music for services and other events.

This near-exclusive power over creative expression meant the Church could dictate taste almost completely. It is hard to know for certain, but we know that the first explicit disapproval of the tritone came from Italian music theorist Guido of Arezzo. At the time, Guido had devised a popular system of organizing chords, which was also a new invention.

Guido replaced the note B♮ (B natural) with B♭ to avoid the tritone naturally occurring in the C major scale between F and B. Was this distaste for the tritone a reflection on the larger attitudes regarding the fine arts in 17th century Europe? Most likely. However, the tritone’s devilish reputation extended into the 18th century when given the unfortunate title diabolus in musica or the devil in music.

Who knows to what extent the Church banned composers from using this interval. According to Musicologist Anthony Pryer, the tritone “…was recognized to be a problem in music right back to the 9th Century [and] a natural consequence, and so they banned it [and] had rules for getting around it. I don’t think they ever thought of it as the Devil dwelling in music.”

The Hands of the Devil

Now that we have some important theory and some useful history about the nature of the tritone, how can we use its mystical powers in our music? Great question!

As we discovered earlier, we rarely hear the tritone as a standalone interval. However, as with everything in music theory, there are many examples to the contrary. One such example is the classic Black Sabbath tune, “Black Sabbath.”

One might listen to this and think that it is precisely what the Church was trying to ban all those centuries ago!

The tritone interval exists inside of every dominant 7th chord. The tritone interval is what gives the dominant 7th chord such a strong resolution to the I chord in a chord progression. Check out this example below:

In this example, the tritone occurs in the top two notes of the G7 chord. The F in the G7 chord resolves down to E in the C major chord, and the B in the G7 chord resolves up to C in the C major chord. This cadence sounds complete and finished but also cliche and trite in the wrong context. If you are a real nerd, you will also notice that the above example has parallel fifths, another no-no for the Church. But that is a topic for another day.

The tritone also exists in the blues scale. The blues scale is a minor pentatonic scale with a flat five scale degree added. Check it out notated below:

There are many other chords besides the dominant 7th chord that contain tritones. Here are a few examples.

Major 7th ♯11

One of the most ephemeral and magical of all chords, the major 7th ♯11 chord contains a tritone between the root and the ♯11th scale degree. Here is a quick dose of theory: if you know about alterations and extensions, you will know that the 11th scale degree is the 4th scale degree one octave higher. Thus, it follows that a chord with a ♯11th scale degree will have a tritone because the augmented fourth is another word for the tritone. Make sense?

Check out some examples below of major 7th ♯11 chords and see if you can work any of these into your next tune! You will find they don’t sound very devilish at all.

Minor 7th ♭5

A darker, more romantic chord, the minor 7th ♭5 chord contains a tritone between the root and the ♭5 scale degree. The formula for a minor 7th ♭5 chord is 1 – ♭3 – ♭5 – ♭7, and the chord is naturally occurring from the 7th degree of the major scale. In the key of C major, this means the corresponding chord is B minor 7th ♭5. We spell this chord B – D – F – A. It looks like this on the staff:
You can go way deep with these chords and find many ways to use and substitute them for dominant 7th chords. Mess around and use your imagination to find new and interesting sounds because no one is in control of your creativity but you!

Conclusion

Despite its devilish history, the tritone is a wonderful and intriguing interval with many uses. The tritone is equal to six half steps and splits the octave perfectly in half, which you can discover by studying the circle of fifths. Many chords and scales include a tritone, such as dominant 7th chords and the blues scale, and many riffs and melodies incorporate a tritone somehow. Check it out, learn its mysteries, and find new ways to create with it!