New York : Human screams possess a unique acoustic signature that activates the brain’s fear centre and is used exclusively to signal danger or distress, a new study has found, reports PTI.
“If you ask a person on the street what’s special about screams, they’ll say that they’re loud or have a higher pitch,” said study senior author David Poeppel, who heads a speech and language processing lab at New York University. “But there’s lots of stuff that’s loud and there’s lots of stuff that’s high pitched, so you’d want a scream to be genuinely useful in a communicative context,” said Poeppel.
Humans make a variety of meaningful noises. Part of what makes us human is how our ears can distinguish speech patterns made from vowels and consonants, which is a step above being able to identify whether a sound is made by a male or female, or by our species or another species.
Where in the brain we process this information is known, but there was one area that scientists assumed didn’t have much to do with human communication. This is where screams come in. Poeppel’s post doc Luc Arnal, now at the University of Geneva, led a series of studies to analyse the properties of screams.
Because there is no repository of human screams, the researchers used recordings taken from YouTube videos, popular films, and volunteer screamers, who were asked to give their all in the lab’s sound booth.
They plotted the sound waves in a manner that reflects the firing of auditory neurons, and they noticed that screams activate a range of acoustic information that scientists hadn’t considered to be important for communication.
“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,” said Poeppel. “In a series of experiments, we saw [that] this observation remained true when we compared screaming to singing and speaking, even across different languages.