Jack-o-lantern in window

What do the best horror movies all have in common?

They all have memorable soundtracks that elicit an instantaneous feeling of terror. In fact, if you watch the films without any sound, they become a great deal less scary.

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

The Fear Response

With respect to evolutionary biology, there’s an obvious survival advantage to the instantaneous recognition of a deadly scenario.

Thinking takes time, 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 consciously.

Since it takes additional time to process and ponder visual information, the animal brain is wired to react 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 find in nature: many vertebrates—humans included—generate and react to harsh, nonlinear sounds and vocalizations when alarmed. This produces a nearly instantaneous sensation of fear or anxiety.

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

When an animal screams, it produces a scratchy, irregular sound that stretches the capacity of the vocal cords beyond their normal range.

Our brains have evolved to recognize the qualities of nonlinear sound as abnormal and suggestive of life-threatening circumstances.

The fascinating thing is, we can artificially reproduce a wide array of these nonlinear sounds to get the same immediate fear response in humans.

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 probably one of the most terrifying scenes in the history of cinema.

But if you watch the scene without sound, it loses the majority of its impact. It’s only once you add back in the high-pitched screaming 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 evaluating the emotional reactions to two types of music.

Participants in the study listened to a selection of emotionally neutral scores and scores that contained nonlinear properties.

As predicted, the music with nonlinear characteristics elicited the strongest emotional reactions and negative feelings. This response is simply an integral part of our anatomy and physiology.

Whether Hollywood comprehends this physiology or not, it appreciates instinctively that the use of nonlinear discordant sound is still the most effective way to get a rise out of the viewers.


Want to observe the fear response in action?

Check out these 10 Essential Horror Movie Scores.