Why Do People Feel Irritated by Screeching Sound on Metal/ Blackboard?

Unpleasant sounds more often trigger negative responses. Think of the time when you start spinning your fork around the spaghetti to enjoy the full-filling platter. And accidentally, it scraps your plate even before you get a chance to grab one or two spaghetti strands.

As a result, the unpleasant sound you hear ultimately distracts your mood. While this was just an example of the screeching sounds that negatively impact your brain, the human nails can also produce scraping noises.

Fingernails on Blackboard: Differentiating between Sounds and Noises

Have you ever wondered why the sound of nails on chalkboards or metals produces an offensive (or even painful) impact on your brain? Scientists claim that there are a few noises that the human brains describe as a negative response. Ever since the 20th century, numerous studies got conducted concerning sounds and noises.

Through a piece of research, the sounds got isolated between high, middle, and low frequencies. Surprisingly, when the middle frequencies were isolated and studied, the sound produced had a resemblance with a warning cry of a chimpanzee. Thus, the waves associated with the primate cries are similar to the mid-frequency sound waves by fingernails on the blackboard.

The human reaction to the sounds has its roots in the predator-feeling instincts ever since the dawn of evolution. The range of frequency (2000-5000 Hz) happens to be the range whereby human ear canals resonate. It results in transmitting the sound more effectively. Professionals claim that it hits the frequency range where human ears are sensitive. That’s how it’s expected to be a stronger response.

Sounds in this particular frequency will active the level of the amygdala. As far as the amygdala goes, it’s a part of the human brain that is associated with fearful responses. As a result, it triggers in the auditory cortex and increases its activity.

Mental Response to the Screeching Sounds on Metal or Chalkboard

Your mind interprets sound with a unique approach. These sounds can get translated via one regulatory process, better referred to as the reticular activating system. It’s right in the brain stem, and it can listen continually throughout the delta-wave sleep.

It helps in determining the predominant aspect of sounds in accordance with waking cortex or the body from a deep sleep. Scraping sounds on a chalkboard elicit emotional responses. These trigger tendencies from those fight or flight responses eventually act as one primary self-defensive mechanism of the body.

Shocking Truth about the Sound of Metals

When metal gets rubbed against another, it’s sure to produce an awful sound. Thinking of the scraping sound in your mind can only make you cringe, isn’t it? One reason might be because these sound frequencies resemble the sound of alarm calls of monkeys or chimpanzees. Another reason why people find it an offensive sound is because humans can hear from 150 to 7,000 Hz.

The Last Call

So, the next time you hear the sound of an electric drill, nails/chalk on a board, fork on a plate, or knife on a glass, remember there’s a reason why these are sounds you hate!


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