What do the top horror movies all have in common?
They all have unforgettable soundtracks that elicit an instant feeling of terror. In fact, if you watch the films without any sound, they become a lot less scary.
But what is it regarding the music that renders it frightening? More specifically, if sounds are merely oscillations in the air, what is it about our biology that causes us to react with fear?
The Fear Response
With respect to evolutionary biology, there’s an obvious survival advantage to the automatic recognition of a life-threatening scenario.
Thinking is time consuming, especially 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 think about visual information, the animal brain is wired to respond to quicker sound-processing mechanisms—a characteristic that offers survival advantage and has been selected for in the wild.
And that’s exactly what we see in nature: several vertebrates—humans included—produce and react to harsh, nonlinear sounds and vocalizations when frightened. This generates a virtually instantaneous sensation of fear or anxiety.
But what is it about nonlinear sound that makes it scary?
When an animal screams, it produces a scratchy, irregular sound that stretches the capacity of the vocal cords beyond their typical range.
Our brains have evolved to distinguish the qualities of nonlinear sound as abnormal and indicative of life-threatening circumstances.
The fascinating thing is, we can artificially simulate a variety of these nonlinear sounds to bring about the same instantaneous fear response in humans.
And so, what was once a successful biological adaptation in the wild has now been co-opted by the movie industry to produce scarier movies.
Music and Fear
We all know the shower scene from the classic movie Psycho, and it’s probably one of the most terrifying scenes in the history of cinema.
But if you watch the scene on mute, it loses the majority of its impact. It’s only when you add back in the high-pitched screeching and bone-chilling staccato music that the fear response becomes thoroughly engaged.
To reveal our instinctive aversion to this nonlinear sound, UCLA evolutionary biologist Daniel Blumstein carried out a study evaluating the emotional responses to two types of music.
Participants in the study listened to a selection of emotionally neutral music scores and scores that incorporated nonlinear properties.
As expected, the music with nonlinear characteristics aroused the strongest emotional responses and negative feelings. This response is simply a part 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 best 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.