Scientists have been trying to understand what drives people to be scared of screams more than any other sound for decades and now we just might have an answer.
Senior author of the study, professor of psychology and neural science at NYU David Poeppel has some interesting thoughts on the whole concept of screams and their relation to fear. He states that most people wrongly assume that screams are special because they are loud.
However Peoppel says that there are many other loud noises and also a lot of high pitched ones, but that none have the communication value of a scream. So the main difference between a human or an animal scream and other sounds is that the scream is meant to convey a message.
The team analyzed the sound waves of different types of screams , some of which were collected from YouTube and several movies, since previously gathered information on the subject was scarce. The team also employed the services of “volunteer screamers” which were asked to howl, shriek and yell.
The aim of this data collection on screaming was to find witch aspect is responsible for the natural human reaction to such noises. This reaction is unique and cannot be replicated using other loud sounds or high pitched noises.
The difference between scream and speech was found using a new sound analysis method called modulation power spectrum. This method helped the team separate sound intensity changes and identify a acoustic range which only screams occupy.
The team asserted that a certain quality called “roughness” is what sets screams apart from any other loud sounds. The abrupt change in sound intensity also identified as “roughness” is what makes screams so different from other sounds.
The team analyzed the correlation between “roughness” and human reactions, using several tests involving screams from horror movies and YouTube clips. The volunteers identified the sounds with the highest levels of “roughness” as the scariest, proving that it was this quality that was mainly responsible for setting such sounds apart.
By monitoring the volunteers’ brain activity while they listened to screams and other sounds, the team was able to identify the portion of the brain which reacted differently.
A part of the brain’s medial lobe called the amigdala was seen to react to the increased fear response generated by screams, and is considered responsible for the way we act when we hear a scream.
Screaming is widely used as a method of communication between different species of animals as well as an information delivery system between members of the same species. Thus some of the reactions humans have when they hear screams could be a remnant of the days when we were not yet kings of the food chain.
Photo Credits popmatters.com