In the past, scientists speculated that certain high-pitched sounds that fall within this Hz range sound so irritating to humans because they are acoustically similar to warning alarm calls in our primate ancestors, and somewhere along the evolutionary roadway humans evolved the innate tendency to find certain sounds emotionally terrifying – part of the “fight or flight” response. Theoretically, this tendency might have been valid, despite the fact that fingernails scratching on a chalkboard have nothing to do with actual predators.
More recent research dilutes the validity of this theory, especially since recent studies on primates found that the animals’ reactions to both high-pitched scraping noises (like nails on a chalkboard) and plain white noise were similar, whereas humans clearly find the high-pitched scraping sounds much more unpleasant.
A simpler hypothesis seems to make more sense – which is that the actual shape of the human ear happens to amplify certain frequencies to a degree that they trigger physical pain. If that’s the case, the repeated sensation of pain associated with these noises may be causing our minds to automatically consider them to be unpleasant.
While researchers in the field of psycho-acoustics continue to study sounds and the brain’s interpretations of them, they may be able to get to the bottom of why certain noises are innately irritating to virtually everyone.
As studies have already proven that noise pollution can exacerbate certain health conditions, including mental health problems such as depression and stress, this newest study may offer insight into the effects of certain frequency sounds on not only people who suffer from emotional disorders, but also on physical disorders such as tinnitus and migraines, in which a heightened perception of unpleasant sounds seems to be at play.
The study’s findings surprised even the researches, as the brain’s emotion centers prove to be more interwoven with noise perception than had previously been known.
On that note, I leave you with a list of the least unpleasant sounds listed in the study, which offers at least one surprise:
2. Baby laughing
4. Water flowing