For years, scientists have wondered why the body reacts differently to sharp piercing screams of terror and now a new study – published in the journal of Current Biology – solves the mystery: experiments conducted explain how high-pitched screams affect the amygdala – an almond shaped organ located in the medial temporal lobe of the brain responsible for processing feelings of fear and sense of danger.
Perhaps, the most defining moments of any horror, thriller movie are ear-splitting, bone-chilling screams and shrieks which make fainted-hearted people head for the exit doors.
“There’s been so much attention paid to understanding speech and song that we’ve really ignored this much more innate vocalization until now,” says Tecumseh Fitch, an evolutionary biologist and cognitive scientist at the University of Austria, who was not involved in the work.
A neuroscientist at the University of Geneva, Luc Arnal, revealed that a scream is definitely different from other sounds because of the “roughness”, an acoustic quality that sets it apart. However, he noted that why the brain finds high screams unpleasant and unsuitable is not so clear.
According to Arnal, normal sound patterns have around 4-5 Hertz of roughness, but that of screams is around 30-150 because they modulate pretty fast.
Using recorded screams used in certain horror movies, volunteers were asked to listen to these screams and tell how sharp, piercing, and distressing they were in order to determine the highest and most frightening scream, which would undoubtedly contain the highest roughness.
To fully understand the pitch and effect of the screams on the brain, the researchers monitored electric activity in the brain of the volunteers using a functional magnetic resonance technique just as the participants listened to the screams.
“And lots of other things are loud and high-pitched,” said neuroscientist David Poeppel of New York University. “It turns out that screams occupy a part of the soundscape that had previously been assumed to be irrelevant to human communication. If you ask someone which [direction] a sound came from, they’ll be faster and much more accurate if it’s a scream,” Poeppel said. “Now, we think that’s because the brain is uniquely tuned to screams.”