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Why Do Certain Sounds Make Our Skin Crawl ?


Why Do Certain Sounds Make Our Skin Crawl ?

 Does the sound of nails scraping at a board or running a fork on a glass plate bother you? Sure enough, just reading these words causes you to feel goosebumps! This leads us to wonder why our bodies behave like this when we hear certain sounds?!

 you are not alone! These and other sounds are universally hated, and there is a biological explanation behind this.

1-Why can't we bear the sound of nails scraping at the board? 

Why can't we bear the sound of nails scraping at the board?

 In 2012, scientists conducted a study where they asked people to rank a list of sounds according to how annoying they were.

 The sounds that reached the top included a knife on the glass, nails on the board, a fork on the glass, and loud screams.

 All of these sounds have a basic similarity, high pitch! It is said that the number of times something happens is its frequency. Likewise, the number of vibrations caused by a sound wave is its frequency. More vibrations correspond to a higher pitched sound.

 Humans can hear sounds in the frequency range between 20 Hz and 20,000 Hz. The frequencies of the above sounds range from 2000 Hz to 5000 Hz. And our ears seem to be most sensitive to this range of sound frequency.

 While the study subjects listened to these sounds, the scientists measured real-time activity in their brains with functional magnetic resonance imaging (fMRI).

 A functional magnetic resonance imaging (fMRI) scan shows activity in the brain by measuring changes in blood flow in the brain.

 An active part of the brain uses more oxygen, which leads to increased blood flow to that specific area.

 The scientists observed that sounds such as scraping nails on a board and scraping a knife against glass caused high activity in two areas of the brain - the auditory cortex and the amygdala.

 As we learned earlier, the auditory cortex is the part of the brain that helps us understand the  sounds we hear every day.

 The amygdala is a small, pocket-like structure known as the "emotional center" of the brain. The amygdala functions in response to the action of hit and run, which is essential for survival.

2-Why do these sounds give us goosebumps?

Why do these sounds give us goosebumps?

 Of all the sounds mentioned, screaming is the only sound that is produced as a "normal" response to a situation.

 Humans are programmed to respond to yelling as if it were a matter of life or death, because in the past it happened so often!

 The calls for help or calls for help made by our primitive ancestors were similar to the sound of a scream.

 Screaming, like any other sound, consists of multiple frequencies. In another study, scientists isolated the different frequencies of intense noises (i.e., screams) and asked individuals to rank them according to the discomfort they caused.

 Surprisingly, it was not the loudest screaming tones that were the most painful to listen to, but the middle frequency tones.

 The frequency of the nail claws on the board exactly matched the average frequencies of the scream. Hence, scientists speculated that the sounds of scraping nails on a board or scraping a fork on a board were setting off the same alarm bells in our heads as a scream, even though our visual cues tell us that nothing is threatening around us.

Why do these sounds give us goosebumps?

 In general, we can say that the goosebumps that get us when hearing the mentioned sounds and others that share the same frequency range is part of the nature of the brain to warn us of danger, and it is the way our bodies have maintained since the Paleolithic humans to respond to danger and prepare for it.

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