This is a scientific Americans 60 second science. I'm Karen Hopkins. This will just take a minute.

Got your attention? Thought so. But what is it about a piercing shriek that really turns our heads?

It's what it does to our brains. The acoustical properties of the human scream

poke at the neural circuits that control fear. That's according to a study in the journal Current Biology.

Our every waking moment is filled with noise,

from planes flying overhead

to various creatures scrambling underfoot.

But a heartfelt cry can cut through all that.

So what's so special about the sound of a screech? To find out,

researchers prepared a sampler of screams from YouTube videos, popular films, and excited volunteers.

If that screech sounded familiar, that's because it's the famous Wilhelm's screen,

a stock sound effect heard in everything from Bugs Bunny to Star Wars.

The scientists analysed the acoustical characteristics of the various screams, and they found

that these alarming sounds are not only loud, they're particularly rough. That is, they rapidly change in frequency.

Normal speech is relatively smooth, with frequencies ranging only between 4 and 5

hurts or cycles per second, but a shriek can swiftly fluctuate between 30 and 150

hurts, a range that can make your hair stand on end. When the researchers asked people

to rate how frightening screams were, they found that more roughness meant more terrifying,

and increasing the roughness of the sound corresponded to greater activation of the fear center of the brain.

Only one other noise scored as high as screams in terms of roughness.

Which ironically is enough to make you.

Thanks for the minute.

...