What do the greatest horror movies all have in common?
They all have memorable soundtracks that bring about an instant sensation of fear. In truth, if you view the films without any sound, they become a great deal less scary.
But what is it about the music that makes it terrifying? More specifically, if sounds are merely vibrations in the air, what is it about our biology that makes us respond with fear?
The Fear Response
In terms of evolutionary biology, there’s an obvious survival advantage to the instantaneous identification of a harmful scenario.
Thinking takes time, particularly when you’re staring a hungry lion in the face. When every second counts, you don’t have the time to stop and process the information consciously.
Since it takes more time to process and ponder visual information, the animal brain is wired to react to swifter sound-processing mechanisms—a trait that provides survival advantage and has been selected for in the wild.
And that’s exactly what we discover in nature: a large number of vertebrates—humans included—generate and respond to harsh, nonlinear sounds and vocalizations when alarmed. This yields a nearly instant sensation of fear or anxiety.
But what is it about nonlinear sound that makes it scary?
When an animal screams, it creates a scratchy, irregular sound that extends the capacity of the vocal cords beyond their normal range.
Our brains have evolved to recognize the qualities of nonlinear sound as unpleasant and suggestive of life-threatening situations.
The interesting thing is, we can artificially reproduce a variety of these nonlinear sounds to bring about the same instantaneous fear response in humans.
So, what was once a successful biological adaptation in the wild has now been co-opted by the movie industry to manufacture scarier films.
Music and Fear
We all know the shower scene from the classic film Psycho, and it’s certainly one of the most terrifying scenes in the history of cinema.
But if you watch the scene without sound, it loses the majority of its impact. It’s only once you add back in the high-pitched screeching and bone-chilling staccato music that the fear response becomes fully engaged.
To demonstrate our instinctive aversion to this nonlinear sound, UCLA evolutionary biologist Daniel Blumstein conducted a study assessing the emotional reactions to two types of music.
Study participants listened to a selection of emotionally neutral music scores and scores that incorporated nonlinear elements.
As expected, the music with nonlinear characteristics aroused the most potent emotional reactions and negative feelings. This response is simply an element of our anatomy and physiology.
Whether Hollywood comprehends this physiology or not, it knows instinctively that the use of nonlinear discordant sound is still the most effective way to get a rise out of the audience.
Want to see the fear response in action?
Check out these 10 Essential Horror Movie Scores.