Scream Study Identifies Unique Acoustic Properties

Human screams have a unique acoustic property that triggers the brain’s fear center more effectively than almost any other sound.
A study at New York University tested a variety of noises and the effect they cause in brain activity.
The study found that screams are distinguished by an acoustic quality known as “roughness” – the rate at which the volume of a sound changes.
In normal spoken conversation, volume cycles around four to five times per second, or 4-5 Hertz.
The roughness of screaming is much higher, between 30-150Hz.
The rising and falling volume is so rapid that it is not perceived as such, but is ultimately what makes screams sound so shrill and unpleasant.