Halloween Hearing: Why Do Certain Sounds Scare Us?

What do the top horror movies all have in common?

They all have unforgettable soundtracks that bring about an instantaneous sensation of fear. Indeed, if you view the films without any sound, they become a great deal less frightening.

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

The Fear Response

In regard to evolutionary biology, there’s an evident survival advantage to the automatic acknowledgment of a deadly situation.

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 longer to process and ponder visual information, the animal brain is wired to react to quicker sound-processing mechanisms—a trait that offers survival advantage and has been selected for in the wild.

And that’s precisely what we see in nature: several vertebrates—humans included—generate and respond to harsh, nonlinear sounds and vocalizations when frightened. This results in a nearly instantaneous feeling 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 past their normal range.

Our brains have evolved to distinguish the qualities of nonlinear sound as abnormal and indicative of life-threatening situations.

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

And so, what was once an effective biological adaptation in nature 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 certainly one of the most terrifying scenes in the history of film.

But if you watch the scene without sound, it loses most of its affect. It’s only when you add back in the high-pitched screeching and bone-chilling staccato music that the fear response becomes fully engaged.

To confirm our natural aversion to this nonlinear sound, UCLA evolutionary biologist Daniel Blumstein carried out a study examining the emotional reactions to two types of music.

Study participants listened to a selection of emotionally neutral music scores and scores that incorporated nonlinear properties.

As expected, the music with nonlinear elements elicited the most powerful emotional responses and negative feelings. This response is simply an element of our anatomy and physiology.

Regardless of whether Hollywood comprehends this physiology or not, it knows intuitively that the use of nonlinear disharmonious sound is still the best way to get a rise out of the viewers.

Want to see the fear response in action?

Listen to these 10 Essential Horror Movie Scores.