What makes scary music so scary? This weekend, I answered that question on Medium, but because today is Halloween, I’ll post an excerpt from it below, explaining one of the reasons why scary music is scary. Visit Medium to read the rest – and find out two other explanations for the scariness of scary music.
Sometimes the use of minor chords and dissonant sounds is enough to evoke a spooky atmosphere. In the Middle Ages, one interval was even referred to as “Devil’s interval”. It refers to the tritone, or augmented 4th. This is the interval between A and E flat, for example, or between D flat and G.
The name Devil’s interval has taken on a life of its own. From the 18th century, people started talking about the interval that was forbidden in medieval times. The name makes it sound mysterious and occult, but it’s likely that it was only called “Devil’s interval” to warn people against using this odd chord that didn’t follow conventional rules of music writing.
The Devil’s interval definitely sounds unpleasant, and does a good job of making scary music sound scary. You can find it in the opening violin chords of Saint Saens’ Danse Macabre.
What makes it so uncomfortable to listen to? It can all be explained with physics. In any two-note chord, each of the individual notes produces a sound wave with a distinct wavelength. This sounds nice when those two sound waves meet again after a one or more of each of their wavelengths. This combination of two waves then creates a new regular pattern. But the two notes that make up the tritone or Devil’s interval have incompatible wavelengths. They don’t meet. Instead of creating a new regular pattern, they form a dissonant sound.