Halloween is coming up! And while well-executed costumes and scary-looking pumpkins can be frightening enough, the creepy sounds of Halloween can truly scare the bejeezus out of us. But sound is really just vibrations – so why do some vibrations trigger instant fear? 

It seems that it’s all about biology. You see, our brains have evolved to fear what’s called non-linear sounds. Non-linear sounds are sound waves that have a very high amplitude and a higher volume in comparison with other sounds. They often contain frequency jumps, non-standard harmonies, or chaos and noise – and you can produce them by abruptly changing the frequency of acoustic instruments. Non-linear sounds, like the cry of an animal or a human scream, are scary to us because they extend beyond the normal capacity of the vocal cords. And our brains have evolved to understand the abnormality in these sounds, so we instantly know something is wrong or that there’s danger close by. In fact, our brains react to these sounds so fast that even the brain itself doesn’t know what’s going on until after we’ve reacted. That’s simply a survival mechanism.

DID YOU KNOW?
Hearing is a mechanical sense that travels through only five nerves before you react. The process is over before your brain really has understood what happened.

An extensive study has shown that movies, and in particular horror movies, are full of non-linear sounds that aim to make what we’re watching more captivating. Did the moviemakers intentionally use them to scare us? Probably. But one thing’s for sure: even if images can be dead scary, evolutionary biology has caused us to be more scared of certain sounds. So, if you scare easily, be sure to mute the worst audio scenes of your upcoming Halloween flicks... and enjoy! Muahahaha!

References
It’s Okay To Be Smart
Scienceabc.com
Heartlandhearingiowa.com