Why are we so annoyed by the scraping of iron on glass or the creak of foam? In general, this cannot even be called irritation, when perceiving certain sounds, a person seems to twitch, goosebumps run through his skin and he begins to feel very uncomfortable.
The answer to this question lies in our brains. In the very depths of the human brain, under the occipital lobes, the cerebellum ("small brain") is hidden - one of the most ancient brain structures. He is in charge of coordinating movements, regulating balance and maintaining muscle tone. This part of the brain is "inherited" by us from very, very ancient ancestors and functionally connects the brain with the spinal cord and "works" absolutely automatically, that is, it is not controlled by consciousness.
One of the parts of the cerebellum is the amygdala. This curious formation is embedded in the limbic system of the brain - the very structure that is responsible for our emotions.
Specifically, the amygdala itself, it turns out, regulates the most ancient "basic" emotions associated with survival: anger, fear, pleasure, - allows you to distinguish the threat from other people and life situations and stores emotionally colored memories. It is she who is responsible for our phobias and panic attacks, as well as for heroism and friendliness.
The amygdala is associated with the cerebral cortex, in particular with its auditory area. Therefore, it is able to distinguish and evaluate (in terms of the presence or absence of a threat) sounds and "give out" responses.
Especially clearly and well the amygdala "distinguishes" unpleasant sounds. This is understandable: an unpleasant sound, as a rule, means a threat, and an ancient brain structure sharpened for survival reacts exactly that way. Moreover, it reacts automatically, without recourse to consciousness. And since the cerebellum, which is responsible for movement, is very close, the notorious goosebumps (reflex, that is, unconscious contraction of small muscles) can become a response.
Well, now let's get back to the creak of polystyrene, the grinding of iron on glass, nails on the board and other unpleasant sounds. As scientists have established, all sounds that people consider unpleasant lie in the mid-frequency range: from 2 to 5 thousand hertz. It is they who, with special force, affect the ancient brain structure - the cerebellar amygdala, literally resurrecting the most ancient emotions.
Why? Because it is in this range that the "speech" of predators lies. For example, a cheetah roars and meows at a frequency of 2, 000 to 6, 000 hertz, a cougar from 2, 000 to 4, 000 hertz, a leopard from 3, 000 to 4, 000 hertz.
So, from the point of view of scientists, the grinding of iron on glass, the creak of foam plastic and other unpleasant sounds remind the brain (or rather, its most ancient structures) the cries of predators.
Since the development of various structures of the brain (including the cerebellar amygdala) is different for different people (the size, presence and density of white matter and even blood supply are very different), then the reaction to these sounds can be seriously different. From indifference and slight discomfort to feelings of fear and panic.
And finally, the 5 most annoying sounds for people:
- Foam squeak
- Microphone screeching
- Chalk creak on board
- Balloon squeak
- Grinding of metal (nails) on glass
What sounds annoy you?