What do the top horror movies all have in common?
They all have memorable soundtracks that bring about an instant sensation of terror. Indeed, if you view the films without any sound, they become a lot less scary.
But what is it about the music that makes it terrifying? More specifically, if sounds are just vibrations in the air, what is it about our biology that makes us react with fear?
The Fear Response
In terms of evolutionary biology, there’s an evident survival advantage to the automatic recognition of a dangerous circumstance.
Thinking is time consuming, particularly when you’re staring a ravenous lion in the face. When every second counts, you don’t have the time to stop and process the information deliberately.
Seeing that it takes additional time to process and ponder visual information, the animal brain is wired to respond to faster sound-processing mechanisms—a characteristic that offers survival advantage and has been selected for in the wild.
And that’s precisely what we see in nature: many vertebrates—humans included—produce and react to harsh, nonlinear sounds and vocalizations when frightened. This produces a nearly instantaneous sensation of fear or anxiety.
But what is it about nonlinear sound that makes it frightening?
When an animal screams, it produces a scratchy, irregular sound that extends the capacity of the vocal cords past their typical range.
Our brains have evolved to detect the characteristics of nonlinear sound as abnormal and suggestive of life-threatening circumstances.
The interesting thing is, we can artificially simulate a wide array of these nonlinear sounds to get the same immediate 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 manufacture scarier movies.
Music and Fear
We all know the shower scene from the classic movie Psycho, and it’s definitely one of the most frightening scenes in the history of film.
But if you watch the scene on mute, it loses the majority of its impact. It’s only once you incorporate back in the high-pitched screeching and bone-chilling staccato music that the fear response becomes thoroughly engaged.
To confirm our instinctive aversion to this nonlinear sound, UCLA evolutionary biologist Daniel Blumstein conducted a study assessing the emotional responses to two types of music.
Study participants listened to a collection of emotionally neutral music scores and scores that incorporated nonlinear elements.
As anticipated, the music with nonlinear characteristics aroused the most powerful emotional responses and negative feelings. This response is simply a natural part of our anatomy and physiology.
Regardless of whether Hollywood understands this physiology or not, it knows instinctively that the use of nonlinear disharmonious sound is still the most effective way to get a rise out of the audience.
Want to see the fear response in action?
Listen to these 10 Essential Horror Movie Scores.