SCREAMS
A sound with its own niche
Normal speech changes at about 4 to 5 Hz. Screams change at 30 to 150 Hz, too fast for the ear to follow, so they sound rough.
Test a sound
THE SCIENCE OF SCARY SOUNDS
Rough sounds
get noticed.
A scream is not just loud or high.
Researchers in Frankfurt, New York and Geneva found that screams flicker in loudness far faster than speech, a quality called roughness. Alarms share it, and film soundtracks borrow it.
30–150 Hz the rough zone
Test a sound- Speech flickers slowly
- Screams flicker fast
- Alarms copy screams
- Roughness grabs attention
THE SHORT ANSWER
It is the flicker,
not the volume.
Roughness is how fast a sound
changes in loudness or pitch.
ALARMS
Alarms land in the same zone
Car and house alarms fell into the same rough range as screams, which suggests alarm makers had captured the modulation of a scream.
See the numbers
FILMS
Soundtracks borrow the chaos
An analysis of clips from more than 100 films found horror films full of harsh, atonal screams, and dramas full of abrupt jumps in pitch.
Read about films
FOUR THINGS TO LISTEN FOR
Hear the roughness
for yourself.
Once you know what roughness is, you start to notice where sound designers put it and where they leave it out.
Compare a voice and a scream
Speech rises and falls gently; a scream has a harsh, buzzing edge. That buzz is fast modulation.
Listen to an alarm up close
Researchers placed car and house alarms in the same rough range as screams. Listen for the harsh, buzzing edge rather than the pitch.
Notice the score, not just the screams
Dramas lean on sudden jumps in pitch; horror leans on harsh, atonal screams.
Watch with and without picture
In a 2012 experiment, added noise made music feel more arousing, but less so once a calm video was playing too.
TWO NUMBERS WORTH KNOWING
Fast flicker,
big reaction.
One number from scream acoustics,
one from a study of film soundtracks.
30–150 Hz
How fast a scream's loudness flickers
Human screams clustered between about 30 and 150 Hz modulation rates, a range separate from speech. Adding roughness to sounds made them easier to detect in several tasks.
SCREAMS · CURRENT BIOLOGY 2015
100+ films
Films whose soundtracks were analysed
UCLA's Daniel Blumstein and colleagues analysed 30-second cuts from more than 100 films across genres, looking for chaotic, unpredictable sounds.
FILMS · BIOLOGY LETTERS 2010
Arnal told Cell Press that adding roughness to alarms might make them faster to process, in the same way a smell is added to natural gas so leaks are noticed.
TEST A SOUND
Is it in the
rough zone?
Pick a sound to see where it sits. The bar shows how far into the rough, alarming range researchers placed it.
Based on Arnal and colleagues, Current Biology (2015), and the Max Planck Society and Cell Press summaries of the study.
IN THE CINEMA
Filmmakers knew
it first.
Researchers analysing film soundtracks found horror films packed with harsh, atonal screams, dramas with abrupt changes in frequency, and adventure films with a surprising number of harsh male screams.
Realistic screams are hard to perform, which is one reason the same recorded cry, known as the Wilhelm scream, has been reused in more than 200 films since 1953. In The Birds, the attacking birds' calls were electronically generated.
Questions
Questions people ask
What is acoustic roughness?
It is the harsh quality a sound has when its loudness or pitch changes very quickly, faster than the ear can break down. In the 2015 scream study, roughness meant modulation between about 30 and 150 Hz.
Are screams just loud, high sounds?
Not quite. NYU's David Poeppel said loudness and pitch are not what make a scream special; screams are modulated in a particular way that sets them apart from other sounds.
Why do alarms sound like screams?
Researchers found artificial alarms in the same rough range as screams. They suggested alarm designers had arrived at the scream's modulation by trial and error.
Do horror films really use different sounds?
A 2010 analysis of clips from more than 100 films found horror soundtracks had many harsh, atonal screams, while dramas used more abrupt jumps in frequency.
Does the picture change how a sound feels?
In a 2012 Biology Letters study, added noise and sudden pitch jumps changed how music felt. With a calm video playing, the video suppressed their effect on arousal, though pleasantness still fell.
Sources
- Max Planck Society: Scream if you have to (2015)
- University of Geneva archive: Arnal et al., Human Screams Occupy a Privileged Niche, Current Biology 2015
- ScienceDaily (Cell Press): What makes a scream a scream (2015)
- Kingston University: Blumstein, Bryant and Kaye, The sound of arousal in music is context-dependent, Biology Letters 2012
- UCLA Blumstein lab: Science News, Chaos makes a scream seem real (2010)
Updated