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What do the top horror movies all have in common?

They all have memorable soundtracks that bring about an immediate sense of terror. As a matter of fact, if you watch the films without any sound, they become a lot less scary.

But what is it about the music that makes 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

With respect to evolutionary biology, there’s an obvious survival advantage to the immediate acknowledgment of a dangerous circumstance.

Thinking is time consuming, especially 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.

Considering it takes longer to process and think about visual information, the animal brain is wired to respond to swifter sound-processing mechanisms—a trait that offers survival advantage and has been selected for in the wild.

And that’s precisely what we discover in nature: several vertebrates—humans included—produce and respond to harsh, nonlinear sounds and vocalizations when alarmed. This creates a virtually instantaneous sensation of fear or anxiety.

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

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

Our brains have evolved to discern the qualities of nonlinear sound as abnormal and indicative of dangerous circumstances.

The interesting thing is, we can artificially replicate a wide array of these nonlinear sounds to bring about the same instant 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 produce 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 cinema.

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

To demonstrate our natural aversion to this nonlinear sound, UCLA evolutionary biologist Daniel Blumstein conducted a study assessing the emotional responses to two types of music.

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

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

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

Want to witness the fear response in action?

Listen to these 10 Essential Horror Movie Scores.

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