Why is the sound of scraping glass with metal uncomfortable?

Because there is an upper and lower limit to the frequency of sound that the human ear can receive.

This sound is about to exceed the upper limit, so people can't stand it.

This sound is similar to the sound made by a certain type of monkey when it perceives a dangerous situation, so there is a theory that it is one of the conditioned reflexes left over from the evolution of humans to avoid danger. The sound of fingernails scratching on the glass chalkboard is indescribably annoying. In the United States, this sound is called "blackboard screech."

What is it that makes people feel uncomfortable when they hear it? Work on this poignant sound began in 1988 at the Neuroscience Institute at Northwestern University. Sound is the vibration of air, and the number of times a wave is formed by vibration in one second is called "frequency number", and the unit is expressed in hertz (Hz).

For example, the sound of a large grandfather clock is low and the frequency is low, while the scream of a jet before takeoff has a high frequency number. The human ear can hear the sound of 20Hz 20000Hz.

The study of the sound of scratching a blackboard begins with the analysis of its frequency structure. Sounds in nature are formed in a concentration with many frequency numbers, and the first reason that can cause people's hearing unpleasantness is the high frequency number. So, the sound of the high frequency number was removed from the sound of the blackboard, but the harsh feeling remained.

Next, focus on the sound with a slightly lower frequency number, and remove the sound with a frequency number in the range of 1000Hz and 2000Hz (the sound of 1000Hz is probably close to the highest range of soprano bel canto), and the result is that the uncomfortable sound is gone. Experiments were also carried out on the magnitude of the sound, in which there was no causal relationship. Therefore, the cause of the hearing discomfort is not the highest frequency in the blackboard sound.

Comparing this sound with the sounds of nature, it was surprising that a monkey's scream (alarm sound) when it sensed that the situation was critical was very similar to the scratching sound of this glass chalkboard. After accepting the results of this experiment, it is speculated that the creepy uncomfortable feeling we feel after hearing this sound may be the "ancient memory" of us humans when we first learned to walk on two legs, that is, the ancient memory that awakened our long-dormant "danger nearby". That is, human beings still have such a conditioned reflex in the process of evolution.

Furthermore, analyzing the screams that people make when they see the horror scenes in the movie, it is said that the frequency of the screams is very similar regardless of the country. It seems that this unpleasant feeling is common, and there may be a major issue that is intertwined with our human origins.

Legend has it that when our ancestors did not know how to express themselves in words, they would make a sound of frequency like scraping glass with metal to warn them of danger, so people would feel uncomfortable hearing such sounds.

Because the human ear will produce such a feeling for a certain frequency of sound, and the sound produced by scraping glass with metal is like this, its frequency is very high, generally speaking, this phenomenon is normal.

Sounds like scraping metal and screaming are uncomfortable mainly due to the high frequency of such sounds, which can be accepted by the human ear at a frequency of 20-20k hertz.

It's the same as you don't want to eat in the toilet.

All in all, the main reason why humans can't accept these sounds is because these sounds can change people's heart rate, blood pressure and other indices.

Why do some humans feel uncomfortable when they hear the sound of a knife scraping glass? Is there any scientific justification?

Because the frequency of the "comfortable" sound that humans can accept is 20Hz-20000Hz, the sound of knives scraping glass and fingernails scraping blackboards exceeds this range, which is a real noise, and humans will be very uncomfortable when they listen to it, and even irritable and irritable.

Because this sound is very sharp, that is, the frequency of this sound is very high, and humans are particularly sensitive to sounds of this frequency, so they will feel very uncomfortable, so they feel very uncomfortable.

Because the vibration frequency generated by the knife scraping the glass is received by the eardrum, due to the special structure of the brain, the eardrum feels uncomfortable with this frequency and feels uncomfortable, and at the same time, the psychological suggestion deepens this feeling.

When people hear a sharp sound, the activity of the almond body will be particularly active, and the feeling of scratching the heart and liver, anxiety and irritability that we feel is also derived from this. The more mainstream and more credible explanation for this situation is the instinct inherited from human evolution and written in genes. It may be that in ancient times, such high-pitched sounds were used to warn of danger, or were similar to the cries of some natural predators, so people now feel disgusted and nervous when they hear similar sounds.

The ancestors of human beings were not as strong as we are now, they have always lived in fear in the face of nature, because the living environment is full of dangers, so they have to pay attention to all kinds of threats from nature at any time, and when they find that the crisis is coming, they will use this warning sound to warn their fellow people to stay away from danger. Obviously, the more sensitive people are to such warnings, the easier it is to survive. Therefore, in the process of survival of the fittest, the surviving human ear canal structure has become more and more sensitive to this sound.

When we hear a similar sound, the body immediately produces all kinds of adverse reactions, which is a manifestation of human instinct. It can be seen that every goosebump we get carries memories from the other side of time and space.

Sounds of this frequency, corresponding to the wavelength of sound waves, are close to, or approximately equal to, the scale of a certain spatial structure of the human auditory senses, so that the resonance causes mechanical vibrations, and it is this vibration that produces the experience of injury. The actual shape of the human ear amplifies some of the frequencies so that it actually causes pain, so we automatically think that this noise is an unpleasant association. But what about good noise?

Researchers found that the sound of running water, thunder, and baby crying were the most unpleasant, and applause was the most pleasant. This sound is very similar to the sound of flesh and bone tearing, and it is possible to tell what surface something sharp is scratching without looking, and all living things have an instinct to stay away from sharp and sharp things.

One is that this kind of offensive sound will change the conductivity of human beings, blood pressure, heart rate and other related indexes, and it is precisely because of the changes in these indices that human beings will unconsciously produce uncomfortable reactions, in fact, this is not only a matter of hearing, but also related to a person's nervous system; 2: As we all know, human beings have gone through a long period of evolution to get to where they are today, and in the process of evolution, there are many voices that carry out warning transmissions, and the above voices are extremely similar to them, so human beings will subconsciously feel inexplicably uncomfortable and afraid of these sounds.

Because the frequency of this sound is very high, and this high frequency is close to the frequency of the heartbeat, and the sound produced is similar to noise, so it is uncomfortable.

Such a sound will affect the conductivity of human beings, and it will also affect blood pressure, which will produce an uncomfortable feeling.

Because the sound frequency of the knife scraping the glass is generally between 2000 and 5000 Hz, and this frequency is the frequency range of Zheng Hupi's ears to make Shengduo's hearing very sensitive, so many people will be very uncomfortable.

It is envious that this sound will prick or irritate the nervous system of the brain, and then it will feel very uncomfortable. And it will also change some indicators of the shirt, and then it will feel very uncomfortable.

Actually, it's a psychological reaction. It's also possible that the sound makes you feel sensitive. Fierce attacks on old lead will send signals to your nervous system. You will feel very irritable. Attendant.

It's because some people's eardrums are relatively thin, so they are very sensitive to some sharp sounds, including me.

There is also a kind of person who is naturally uncomfortable with this kind of sound, for example, when I hear the sound of metal sliding on the cement road, I feel the innermost feeling of the teeth, this is not a disease, this is the natural reaction of our body, sometimes we hear a very high frequency of screams, and we will also feel uncomfortable. Generally, such a person will not be able to cook, because when cooking, the shovel or spoon will collide with the pot, which will make a sound, making the person unable to cook.

In addition, having this uncomfortable feeling is our psychological effect, and it is generally the first time we feel uncomfortable. Then it will form a memory in our brain, and then it will be time to hear it again. We will feel uncomfortable again because of the last situation, in fact, sometimes it is just our psychological effect, as long as we can overcome our own heart, then we will not feel uncomfortable next time.

This is a very normal psychological condition, don't worry too much, everyone has their own times when they don't adapt, so as long as we adapt, then we will come out of this shadow. The main thing is that our human body is a very wonderful thing, and it should be the most sophisticated instrument in the world, so if we are a little dissatisfied, we will be uncomfortable. Just try to make our psyche as strong as possible.

Sound is transmitted through air vibrations, and metal friction vibrations of this frequency make people's eardrums very uncomfortable, so they can't stand it. Whether the sound is good or not is a question of vibration frequency. For example, humans can't hear infrasound, but vibrations of this frequency can kill people invisibly. ‍‍

In daily life, we often hear some sounds, such as fingernails scratching the blackboard, metal or foam rubbing glass, teeth slipping, etc., it will be from the physical to the psychological all-round torture, so what is the reason for this phenomenon? <>

Researchers found that the frequency of these crashing sounds is between 2000hz-5000hz, the frequency of this sound is higher, higher than the normal range that humans can bear, there are two boundaries in physiology, one is the sound frequency that we can usually bear, and the other is the sound frequency that we can't bear, and the body will automatically divide the sound frequency that can't be tolerated into noise, which will make the human brain, will subconsciously produce irritability and resistance. So we hate this high-frequency sound. The frequency of this vibration, although high, is close to the frequency at which our heart beats. Surprisingly, the structure of the human ear canal resonates at this frequency, which can amplify this audio, which means that the human ear is very sensitive to sound at this frequency.

When the human ear receives this sound, it will trigger the auditory cortex and the amygdala in the brain, and the communication signal between these two areas rises sharply, this amygdala is the part of the human brain that specializes in processing negative emotions, when he is triggered, people will show anxiety, nausea, fear, trembling, irritability and other adverse reactions, compared with various sounds in nature, it was found that this sound is very similar to the primate warning sound, so a conclusion was drawn, The reason why we have this reaction is probably the conditioning mechanism left over from our ancestors in the process of evolution. <>

I don't know how my teeth are structured, and when I chew something, it's the sound of a knife scraping glass. You can't stop people from eating! I had to endure it, and it was very uncomfortable.

Because the sound of the knife scraping the glass is particularly harsh, and it is so harsh that people feel uncomfortable. In addition, the sound of the knife scraping the glass is too high in decibels, which seriously affects the eardrum, so it will feel particularly uncomfortable.

Because some people listened to the sound of a knife scraping glass, vibrating their eardrums, and the eardrums vibrated and felt very uncomfortable.

This is a problem with our own ears, when our ears hear this harsh sound, it can trigger its internal communication signal to rise suddenly, making the body feel very uncomfortable.

This is closely related to the nervous system, and I am like that, and it is very uncomfortable to think about that situation in my head, and I should avoid that kind of situation.

The sound of a knife slicing through glass sounds harsh and gives you goosebumps when it comes to scraping the thin layer of skin on top of an apple.

I'm in the same situation, every time I hear a sound like a blackboard with my fingernails, I feel very uncomfortable and I can't stand it!!

Because knives and glass are both harder substances, when two harder substances come into contact with each other, there will naturally be a harsh sound.

Because this sound is harsh, it is noise, and the ears will feel uncomfortable when they hear this noise.

The rattling sound is not good! Makes nasty sound waves.