If the sound of nails scraping across a chalkboard makes you clench your teeth and curl your hands into fists, you’re not alone. In fact, it’s one of many sounds out there that the majority of people just can’t stand to hear. What is about them that makes us cringe?

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As it turns out, there are actually a few factors at play, and some of them could even be indicative of a more serious sound-related disorder that can make even the calmest person explode with anger.

Why do certain sounds make us tick?

To put it simply, the annoyance lies in the source of the sound and the shape of our ear canals. In the past, research explained that the sounds we tend to hate often lie right in the middle of frequencies that are audible to humans. However, the big hole in this research is that it didn’t identify which specific frequencies they were and what about them made us hate hearing them. To fill in the gaps, two musicologists named Christoph Reuter and Michael Oehler set out to figure out why.

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First, they had a group of listeners take a test in which they ranked certain sounds they heard. The sounds of nails dragging against a chalkboard and the sound of chalk scraping against slate were consistently the most hated sounds among the participants. They then modified the sounds that participants disliked the most, removing or changing their frequencies, tones, and pitches.

They also told some participants what the sounds really came from, while they told others that the sounds were extracted from musical compositions. The listeners were then asked to rate the sounds again, this time while their vital signs were monitored for any signs of stress.

Surprisingly, it changed their opinions.

Overall, the listeners gave better ratings to sounds they were told came from musical compositions. However, researchers also took note of their skin’s electrical conductivity as they listened and gave their ratings, and found that it consistently changed for sounds the listeners previously said were unpleasant, even when they verbally said they found the modified sound to be less unpleasant than others.

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This change was even more consistent when the listener heard a sound they actually rated as unpleasant, meaning that unpleasant sounds can actually cause physical symptoms.

Their research determined that the sounds that consistently hurt human ears fall into the 2,000 to 4,000 hertz range. They found that removing frequencies in this range made listeners rate the sound as more pleasant, as well as removing tonal portions of a sound.

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The shape of our ear canals come into play because research has shown that they typically amplify frequencies within that range of 2,000 to 4,000 hertz, among others, making them sound worse to us than they actually are.

Another musicologist named Richard Kopiez, of Germany’s Hanover University, says the study provides a lot of insight into how context can play into whether or not someone enjoys music. For example, someone might not love the music they’re hearing at a concert, but they may still be able to appreciate it because they can see where it’s coming from.

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“The audience enjoys the performance because of the knowledge about the (artistic) origins of a sound, although the physiological response remains the same as for uncomfortable sounds,” he said.

True hatred of certain sounds is a little different, though.

Have you ever heard someone chewing with their mouth open and wanted to knock their fork out of their hand? Or maybe it’s that they’re just breathing too loudly and it’s suddenly all you can focus on. For most people, these are just annoying things that we can usually get over without making a scene but, for others, hearing things like this can actually make them violent.

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It’s part of a disorder called misophonia, a condition that is defined by a hatred of sounds. While some might think those with the disorder are just being dramatic, research has shown that those with misophonia actually have a different structure to their brain’s frontal lobe than those who don’t.

One study revealed that the activity in the brains of sufferers noticeably changed when they heard a sound they considered to be a trigger for their condition, and that differences within their brain’s emotional control mechanism is what causes them to react the way they do.

However, the condition isn’t always severe.

For some people with misophonia, which is also referred to as selective sound sensitivity syndrome, the reaction is mild. They may just feel slightly anxious, uncomfortable, or even mildly disgusted. Sometimes, they might remove themselves from the situation entirely to escape the noise. In more severe cases, though, they might experience:

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-Intense feelings of anger, rage, or hatred

-Full-blown panic attacks and fear

-A crawling sensation on their skin

-An intense, sometimes violent, desire to stop whatever is making the noise

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In some cases, whether mild or severe, the sufferer even reacts to visual cues, like someone shaking their foot or rubbing their hand up and down their arm repeatedly. Unfortunately, it’s not a disorder that will typically go away, though people with it have figured out plenty of ways to get around it, like using inner-ear devices that provide constant, soft background noises.