What is the devil’s interval in music – The tritone?

Have you heard of the ‘Devil’s Interval’ in music? Did you ever wonder where the name ‘Devil’s Interval’ came from? Also known as the tritone, it is an interval that is extremely dissonant. So much that it was avoided by music composers for hundreds of years. In fact, it was even banned by the church.

What is the tritone?

Essentially, a tritone interval contains notes that are three toes apart. Or in other words, the notes are six semitones apart hence perfectly dividing the scale into two equal parts. This means that in a single diatonic scale, there would be only a single tritone. This would occur between the fourth and the seventh degrees. So in the case of the C major scale, the tritone would be F and B. Similarly, in the case of G major, the tritone would be C and F.

If you are into music theory, you would know for sure that every particular mode in music corresponds to a particular mood (flavor/character). For instance, the Lydian and the Ionian mode gives off a happy and joyful vibe. On the other hand, Phrygian and Dorian mode gives off a sad and gloomy vibe.

The mode system works quite efficiently for all notes in a scale until, the note B. Named as the Locrian mode, it happened to be the only mode not having a perfect fifth as the fifth degree in the scale. Instead, it was an augmented fourth or a flattened fifth hence giving rise to a triton.

Due to the dissonant nature of the tritone, the Locrian scale was rare to be used. So in order to find a way out, composers kind of tampered with to B-F interval that had a devilish sound to it. This marked the birth of B flat and F sharp.

The major reason why pitches give off a harmonious feel is that harmonious pitches carry a frequency ratio. For instance, two notes that are an octave apart carry a frequency ratio of 2:1 making both the pitches highly consonant. Apart from 2:1, the 3:2 ratio is yet another consonant one which refers to the perfect fifth interval.

Coming back to the tritone, it carries a frequency ratio of 64:65 or 45:32, which depends on your tuning. Nevertheless, this frequency ratio gives rise to an interval that is simply unpleasant to hear and has an altogether satanic/devilish vibe to it. Despite that, the tritone has found its way into modern mainstream music where it is used in impressive ways.

Was the devil’s interval (tritone) banned?

It is said that the tritone was totally banned by churches, and use of it in church music could actually result in a punishment as it was looked down upon. Perhaps this is where this interval got its name i.e. the devil’s interval.

However, it is likely that the churches and religious dwellings had banned the tritone due to purely musical reasons, and not because people believed it was a work of the devil. Provided, that this is not just another rumor.