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:
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.
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:
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:
Major 7th ♯11
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.