Why Screams Are Rough On The Brain

New research pinpoints the acoustic ingredient that gives screams their terror.

Charles Q. Choi, Contributor

(Inside Science) -- Bloodcurdling screams in horror movies often send tingles down people's spines, even though they know such shrieks are fake. Now scientists have discovered the key ingredient of screams that activates the brain's fear circuitry. Inventors may have unknowingly copied this hair-raising acoustic feature into alarms found in cars and houses.

Screaming is apparently innate in origin. Many animals do it too, which suggests that the harsh sound is ancient in origin, and it may be an ancestor of more complex forms of communication. Screams can also be key to survival. They can either call for help or warn others of a life-threatening emergency.

However, surprisingly little research has investigated human screams, said study lead author Luc Arnal, a cognitive neuroscientist at the University of Geneva in Switzerland.

"I started being interested in screams when a friend of mine told me that the sound of his newborn's screams were hijacking his brain," Arnal explained.

Conventional thinking suggested that what sets screams apart from other sounds are their loudness or high pitch. However, many sounds that are loud and high-pitched do not raise goosebumps like screams can, the researchers noted.

To find out what makes human screams unique, Arnal and his colleagues first used their lab's sound booth to record four different kinds of sounds from 19 volunteers: screams, screamed sentences, meaningless sounds such as "ahhh," and sentences spoken in a normal tone of voice. "The recording part was a lot of fun," Arnal recalled. "One part of the recording session consisted of screaming sentences like 'Get the f--- away!'" He added the screams sounded realistic enough to spur unsuspecting students nearby to want to call the police.