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  • Why Nails Scratching a Blackboard Is So Unbearable?

    Why Nails Scratching a Blackboard Is So Unbearable?

    The sound of fingernails on unpainted clay, chalk on a chalkboard, or a knife on a porcelain plate causes the majority of people to irk, cringe, or squirm, and for many, the sound is almost intolerable. It scratches, scrapes, screeches, and squeals, and it is certain to provide goosebumps. Why are we so sensitive to this sound in particular since the contributing factors to these discords are, in most cases, not harmful?

    Multiple hypotheses 

    Quite a few researchers in the scientific community have already attempted to answer this question and have produced multiple hypotheses as a result. An Ig Nobel Prize was even given for the research that was conducted by the team at Vanderbilt University that was led by psychologist Randolph Blake. The sound of a rake being used to scrape a chalkboard was captured by Blake and his colleagues, who did the scraping in a school. Then, they broke the sound into its different frequency ranges and tried to figure out which frequencies seemed to hurt their ears the most.

    Most painful are the middle-frequency bands

    Surprisingly, it’s not the high, shrill frequencies that are the problem, but rather the frequencies in the middle range. When the researchers eliminated this frequency range from the noise, the majority of the individuals stated that it appeared far less disturbing. On the other hand, Blake and his colleagues heard a striking resemblance between the screaming sound and another sound, which they identified as the alarm call of chimpanzees. This ear-splitting shriek sounds very similar to fingernails scratching over a chalkboard.

    Ancient roots

    Is it possible that our natural reaction to these noises is a holdover from the time when early humans made sounds very similar to those as a kind of warning? In yet another piece of research, researchers from Newcastle University, led by Sukhbinder Kumar, revealed that screeching causes a normal anxiety reaction in the brain. This finding shows, at the very least, the potential. The more irritating the sound of scratching is, the more active the amygdala becomes. The amygdala is the part of the brain that is responsible for the sensation of fear.

    Experiencing a resonance in the ear canal

    Musicologists Michael Oehler and Christoph Reuter were even able to exactly calculate the disagreeable frequency range. According to their research, the frequency range between 2,000 and 4,000 hertz is where it screeches in a really eerie manner. They hypothesize that the form of the human ear, namely the ear canal, may be to blame for this. Resonance effects make the corresponding frequencies louder, and they also make the ear more sensitive in this area than it would be otherwise. This can make the squealing sound so painful that it hurts to hear it.

    However, the relationship between cause and effect is not completely known. For example, did our ears develop to be more sensitive to alarm calls, or do apes and potentially early humans employ the frequency range that is most sensitive to communicate their warnings?

  • Why Do Spicy Foods Hurt?

    Why Do Spicy Foods Hurt?

    Anyone who enjoys spicy curries is familiar with the sensation of having their tongue and mouth region burn and their body suddenly become very heated and sweaty. Tears, stomach cramps, and, in the worst cases, nausea and vomiting could be the result of eating very spicy chili peppers.

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    Yet, why? When we consume spicy food, what happens to our body physiologically?

    Humans have taste buds that pick up on five different flavors: sweet, sour, bitter, salty, and umami, the latter of which is the spicy flavor associated with protein-rich cuisine or soy sauce. When we consume anything salty, for instance, our saliva carries the salt to the taste buds, where it gets detected. On the other hand, the bitterness or sharpness in spicy foods is sensed in a manner unrelated to the tongue’s taste receptors.

    Sharpness is “fooling” our receptors

    Piperine chemical compound in pepper.
    Piperine is a chemical compound in pepper. (Credit: ResearchGate)

    This is caused by the active chemicals in spicy foods, such as the piperine in pepper, the mustard oil in horseradish and mustard, the allicin in garlic, the isoalliin in onions, the gingerol and shogaol in ginger, and the capsaicin in chilies.

    When these molecules reach our tongues, they irritate pain receptors like the so-called TRP channels, which are also responsible for the experience of heat and serve as a burn warning system. The sharp stimulus from bitterness causes not just pain but also heat perception, “fooling” our receptors.

    The sensation of heat

    The nerve cells of the mouth secrete chemical messengers called neuropeptides in response to intense heat impulses, such as capsaicin from chili peppers. These trigger a response in our neural system. The blood vessels widen as a result. This increases heat loss by increasing blood flow to the skin’s surface.

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    However, in severe circumstances, this might cause a reduction in blood pressure and circulation issues.

    The glands also increase their output of fluids like sweat and tears. The evaporation of sweat from the skin results in the cooling of the human body. Since the active substances stay on the tongue after swallowing the spicy food, the resulting effects on the body are prolonged. The “burning” in our lips persists, and we experience an increase in body temperature and sweating.

    The brain, too, has an emotional response to sharpness, producing chemicals like adrenaline and endorphins (the latter of which works as the body’s natural pain inhibitors but can also generate emotions of enjoyment) in response to spicy, sharp foods. Spiciness, in large enough quantities, may even intoxicate us. “Pepper High Effect” is another name for this phenomenon.

    Digestion is also affected

    Capsaicin, which is found in chili peppers, speeds up your metabolism and gets the digestive system working better. This is due to the fact that the active component causes irritation in a variety of different receptors and the stomach lining. This prompts the stomach to contract more forcefully and secrete more gastric acid than normal in an effort to get rid of the heat as fast as possible. The digestion process is sped up as a result.

    The heat from chili peppers has been shown to increase metabolic rate and improve digestion in rodent studies, which may explain why some people report feeling more “full” after eating spicy foods.

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    When added to a high-fat meal, capsaicin prevented weight gain in rats. They were also more active than usual despite the abundance of food. Scientists are investigating whether or not capsaicin may increase thermogenesis (body heat) and hence fat burning.
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    Cons and pros of spicy foods

    In addition to the heated active substances, many spicy meals also include additional ingredients that offer health benefits. Ginger, for instance, is often recommended for those experiencing gas and bloating. Garlic has been linked to lowering blood cholesterol levels and helping manage high blood pressure, while horseradish has been touted for its antimicrobial properties.

    However, not everyone can handle spicy meals despite their health benefits. Spicy foods may irritate the mucous membranes, leading to sickness, vomiting, and even high blood pressure in persons with weak stomachs. Spicy foods may initially be too much for some people, but they may develop a tolerance over time if they are introduced to them gradually. Nonetheless, it’s best to keep kids away from chili and other spicy foods.

    Fat to extinguish everything

    Fat, such as mascarpone, cream, milk, or oil, helps with the burning feel of spicy foods, as the pungent active ingredients are fat-soluble and can combine with the capsaicin on the tongue, for example, to wash down the spiciness if a dish is too spicy and painful. Water usually does not help with the burning feeling from spicy foods since it only distributes the active ingredients on the tongue without actually combining with them.