What do the top-rated horror movies all have in common?
They all have memorable soundtracks that elicit an instant feeling of fear. In fact, if you view the films without any sound, they become a lot less frightening.
But what is it about the music that renders it frightening? 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 evident survival advantage to the instantaneous detection of a risky scenario.
Thinking is time-consuming, 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 deliberately.
Given that it takes longer 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 precisely what we discover in nature: a large number of vertebrates—humans included—emit and react to harsh, nonlinear sounds and vocalizations when frightened. This creates a nearly instantaneous sensation of fear or anxiety.
But what is it about nonlinear sound that makes it frightening?
When an animal screams, it generates a scratchy, irregular sound that extends the capacity of the vocal cords past their normal range.
Our brains have evolved to detect the features of nonlinear sound as abnormal and indicative of hazardous circumstances.
The fascinating thing is, we can artificially emulate a variety of these nonlinear sounds to bring about the same immediate fear response in humans.
So, what was once a successful biological adaptation in nature has now been co-opted by the movie industry to produce scarier movies.
Music and Fear
We all are familiar with the shower scene from the classic movie Psycho, and it’s definitely one of the most frightening scenes in the history of cinema.
But if you watch the scene on mute, it loses most 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 demonstrate our instinctive aversion to this nonlinear sound, UCLA evolutionary biologist Daniel Blumstein carried out a study investigating the emotional responses to two types of music.
Participants in the study listened to a selection of emotionally neutral music scores and scores that included nonlinear properties.
As expected, the music with nonlinear elements aroused the most powerful emotional reactions and negative feelings. This response is simply an element of our anatomy and physiology.
Whether Hollywood comprehends this physiology or not, it appreciates intuitively that the use of nonlinear disharmonious sound is still the best way to get a rise out of the audience.