Jack-o-lantern in window

What do the top horror movies all have in common?

They all have unforgettable soundtracks that arouse an instantaneous sensation of fear. In fact, if you watch the films without any sound, they become a lot less frightening.

But what is it regarding the music that renders it terrifying? More specifically, if sounds are just oscillations in the air, what is it about our biology that causes us to respond with fear?

The Fear Response

With respect to evolutionary biology, there’s an evident survival advantage to the instantaneous recognition of a risky 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.

Considering it takes additional time to process and contemplate visual information, the animal brain is wired to respond to quicker sound-processing mechanisms—a characteristic that provides survival advantage and has been selected for in the wild.

And that’s exactly what we see in nature: numerous vertebrates—humans included—generate and react to harsh, nonlinear sounds and vocalizations when frightened. This creates a virtually instant sensation of fear or anxiety.

But what is it about nonlinear sound that makes it alarming?

When an animal screams, it creates a scratchy, irregular sound that stretches the capacity of the vocal cords past their typical range.

Our brains have evolved to distinguish the features of nonlinear sound as abnormal and indicative of hazardous circumstances.

The intriguing thing is, we can artificially simulate a wide array of these nonlinear sounds to bring about the same instantaneous fear response in humans.

And so, what was once an effective biological adaptation in the wild has now been co-opted by the movie industry to manufacture scarier films.

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 film.

But if you watch the scene without sound, 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 conducted a study investigating the emotional reactions to two types of music.

Participants in the study listened to a collection of emotionally neutral music scores and scores that included nonlinear elements.

As predicted, the music with nonlinear elements aroused the most potent 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 discordant sound is still the best way to get a rise out of the audience.


Want to observe the fear response in action?

Listen to these 10 Essential Horror Movie Scores.