There's a reason horror movies are full of bloodcurdling screams instead of bloodcurdling whistling, and now scientists can fully explain it.
Live Science reports that David Poeppel, a psychology and neural science professor at New York University, studied YouTube videos and feature films and even brought in volunteer screamers to study why screaming — as compared to any other loud, disorienting sounds — makes us scared.
"We found that screams occupy a reserved chunk of the auditory spectrum, but we wanted to go through a whole bunch of sounds to verify that this area is unique to screams," Poeppel told Live Science. "In a series of experiments, we saw [that] this observation remained true when we compared screaming to singing and speaking, even across different languages. The only exception — and what was peculiar and cool — is that alarm signals [like car alarms] also activate the range set aside for screams."
As Poeppel and Luc Arnal, lead author who worked on the study published in the science journal Cell Press, told Live Science, the cool science behind this type of sound analysis called the modulation power spectrum, which, according to the Journal of Neuroscience, quantifies the frequency and amplitude modulations in sound that your brain subconsciously recognizes.
Poeppel and Arnal's study sought to investigate the roughness, or the dramatically rising volume, in both natural (human screaming) and artificial (car alarm) signals. The higher the scream's roughness, the more it activates the brain's amygdala, the more in danger a person feels. And, as the report's able to quantify, a scream can scare the bejesus out of someone.
Poeppel's team points out that conversational speech has a relatively low volume, around 4 to 5 hertz. Screams, especially on the super high end, exhibit an electrical signal modulating up to 30 times faster — think Janet Leigh's scream in Psycho all the way up to those wet, nasty yowls in the Saw series.
"Screaming really works," Poeppel told Live Science. "It is one of the earliest sounds that everyone makes. ... This is a way to gain some interesting insights as to what brains have in common with respect to vocalization."
That's why, instead of just being annoyed by your house's smoke alarm, you feel a sense of panic. Which is a real pain in the ass for anyone who has to keep a group of people calm during a fire alarm.