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What do the top horror movies all have in common?

They all have memorable soundtracks that arouse an immediate sensation of fear. In fact, if you watch 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 makes us react with fear?

The Fear Response

In regard to evolutionary biology, there’s an evident survival advantage to the immediate detection of a deadly circumstance.

Thinking takes time, especially 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 contemplate 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 discover in nature: several vertebrates—humans included—produce and react 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 beyond their normal range.

Our brains have evolved to discern the characteristics of nonlinear sound as abnormal and suggestive of hazardous circumstances.

The fascinating 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 a successful biological adaptation in the wild has now been co-opted by the movie industry to produce scarier movies.

Music and Fear

We all know the shower scene from the classic film Psycho, and it’s certainly one of the most terrifying scenes in the history of cinema.

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

To confirm our instinctive aversion to this nonlinear sound, UCLA evolutionary biologist Daniel Blumstein conducted a study evaluating the emotional reactions to two types of music.

Study participants listened to a selection of emotionally neutral music scores and scores that included nonlinear elements.

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

Regardless of whether Hollywood comprehends 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 see the fear response in action?

Listen to these 10 Essential Horror Movie Scores.

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