Washington DC: Neuroscientists have identified the "acoustic signature" of screams, suggesting that we are able to generate sounds reserved exclusively for signaling distress.
David Poeppel, a professor in New York University, said that everybody screams and everybody has an intuition about what constitutes screams, that they are loud and high-pitched.
However, screams have their own acoustic niche separate from other sounds.
While, like some sounds, they may be high-pitched and loud, screams are modulated in a particular way that sets them apart from the rest.
The researchers identified the nature of a particular acoustic characteristic that is specific to screams.
Poeppel explained that screams have trait called "roughness," which refers to how fast a sound changes in loudness and said that a standard measure of sound amplitude modulation-how loudness changes in speech-is Hertz (Hz), or cycles per second. Normal speech rates are typically between four and five Hz, but for roughness, the rate is between 30 and 150 Hz-a remarkably higher rate.
The research team conducted both experiments and analyses that measured sound modulation and identified which parts of the brain were active while listening to screams and other sounds.
The findings show that screams occupy a privileged acoustic niche that, because they are separated from other communication signals, ensures their biological and ultimately social efficiency-we use them only when we need them.
The findings are published in the journal Current Biology.