In the laboratory, sounds become mysterious and beautiful. What is often taken for granted in the outside world, transforming into sound waves and frequencies, changes scientific ideas.
Here sounds change their structure, reveal incredible properties and are found in unexpected places. Sound can also have amazing effects on the human brain. Today we will tell you about ten interesting scientific discoveries related to sound.
10. Sounds can explain the process of anesthesia
Traditionally in medicine, it is believed that nerve cells "talk" to each other using electrical impulses. They are signal channels through which the command is transmitted from the brain to the hand to wave a brush or pet the cat. This does not sound convincing to physicists. The laws of thermodynamics state that electrical impulses must generate heat, but this is not observed in the human body. Physicists have proposed another hypothesis: nerves do not transmit electricity, but sound waves. Not all scientists agree, but it could explain a long-standing medical mystery.
Anesthetic drugs have been around for a long time, but there is still no firm conviction as to how they manage to reduce the sensitivity of the body. Nerve cells have membranes. To transmit audio messages, they must be at a temperature corresponding to the normal temperature of the human body. It is possible that anesthetic drugs alter the intracellular temperature, making the membranes unable to transmit sound waves containing pain signals.
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9. The visual system can be associated with the auditory
Another experiment with monkeys made everyone open their mouths. The monkeys were trained to touch the spot of light every time it appeared on the panel. When the spot was bright, the monkeys did it with ease; when the spot was dull, the monkeys began to experience difficulty. However, when the appearance of the faint spot was accompanied by a sharp sound, the monkeys touched it so quickly that there was only one explanation - the brain could use the sound to see better.
This is contrary to traditional ideas about the nervous system. It used to be thought that the auditory and visual parts of the brain were not connected to each other. However, targeted observation of 49 visual neurons in monkey brains proved otherwise. In the presence of a sound signal at the dim spot, the neurons behaved as if the eyes were seeing brighter light than they actually were. The reaction time was so fast that only the presence of a direct connection between the auditory and visual parts of the brain could explain this.
This interconnection of sensory systems may explain the improvement in vision in the deaf and the frequent presence of acute hearing in the blind. An area of the brain that was previously responsible for the lost property is re-targeted to another area.
8. New method of blood analysis
Blood tests are the cornerstone of making a correct diagnosis, but they are difficult. Common blood testing techniques can take a long time, samples can be damaged and there is a risk of infection. Laboratories are difficult to transport.
Recently, a new method has emerged that reverses all of this. Blood can now be tested with sound waves and a quick and accurate result is obtained. When scientists want information about a patient's condition, they hunt for exosomes. These tiny messengers secreted by cells can tell a lot about the health of the body and its disorders.
The new technique is based on the separation of cells, platelets, and exosomes using sound vibrations at different frequencies. The blood is exposed to acoustic vibrations for a very short time, which prevents damage to the sample.
The use of sound for blood analysis offers great possibilities. Rapid diagnosis, tests of previously hard-to-reach organs, refusal in many cases from a previously required biopsy are just a few of the advantages. One of the most valuable features is that testing can be carried out using a portable kit that can be used in everything from ambulances to isolated villages.
7. Response to levitation
Aeronautics enthusiasts have tried to overcome gravity in every possible way, from magnets to lasers. It turns out the answer is sound waves. In 2014, the University of Scotland discovered that they could probably be used to lift objects.
Sound waves create pressure on the environment, in our case, on the air. This pressure can be used to create levitation. However, scientists failed to create a working device.
The problem turned out to be traditional. To overcome gravity, waves must be emitted in a specific order. To keep an object in a horizontal stationary position or make it move in the desired direction, it is necessary that the pressure on all points is the same. This requires extremely complex mathematical calculations.
Recently, another group of scientists used special software and data from Scottish researchers to create a magical specimen. They found three combinations and even successfully created a three-dimensional sound field using 64 tiny speakers.
The field, called "acoustic hologram", successfully keeps polystyrene balls in the air. Using three different combinations of sound, the researchers were able to make the balls stick together, stand still, or stay within a cage of sound vibrations.
6. Sound can extinguish fire
At first, teachers at George Mason University in Virginia refused to believe in the success of their two students. Two future engineers decided to extinguish the flame with sound waves. Previous research on this issue piqued their interest and desire to come up with the first sound extinguisher.
Since they were electronics engineers and programmers, not chemists, at first they received mostly ridicule instead of support. But 23-year-old Seth Robertson and 28-year-old Viet Tran still continued their tests, under the guidance of a single professor and sometimes with their own money.
They quickly abandoned music, as the waves were too chaotic to extinguish the fire. The main idea of this method is to block access to the fire to feed it with oxygen. This was done when low-frequency vibrations in the range from 30 to 60 hertz were applied to the fire.
Sound vibrations create a rarefied area with little oxygen. The lack of oxygen makes the flame go out. To create a portable fire extinguisher, a lot of work is required, you need to test the fire extinguisher on different types of fuel and forms of ignition. But the opening opens the door to better extinguishing media that do not leave behind toxins like conventional fire extinguishers.
5. Sound changes taste
Low frequency sounds not only extinguish fires. They also give food a bitter taste. At the other end of the scale, their high-frequency counterparts add a bit of sweetness.
The reason for this is not entirely clear, but numerous experiments in laboratories and restaurants have confirmed that sounds affect taste. The researchers called this "taste modulation." Sounds seem to add bitterness or sweetness to almost everything from cake to coffee.
This unusual effect does not affect the taste buds as such. Sounds seem to influence how the brain perceives taste information. The high or low notes of the frequency make him pay more attention to the sweet or bitter flavor of the food.
Noise can also negatively affect appetite. A 2011 study showed that background noise can play a big role. If it is too loud, people feel less salt and sweetness and do not enjoy their food. This explains why noisy restaurants can have bad food and why airlines have a bad reputation in this area.
4. Symphonies of data
Mark Ballora grew up in a musical family. Later, during his doctoral studies, he became interested in turning information into music. He took up sonification - the translation of dry data into sound waves.
Over the next two decades, Ballora created songs that contained data from several studies, including the energy of a neutron star, the body temperature cycles of Arctic squirrels, solar radiation, and tropical storms.
When creating the next symphony, Ballora first gets acquainted with the information and the subject of research. Then he selects sounds that match the numbers and nature of the study.
The swirling sounds correspond to a tropical storm. The solar wind, set to music, created a melody of "changes and flickers". Although this has not become widespread in the scientific world, sonification has received some recognition in astronomy.
At the South African Astronomical Observatory in Cape Town, blind astrophysicist Wanda Merced listens to the received data. She discovered that stellar explosions produce electromagnetic waves when particles exchange energy as a result. Her sighted colleagues missed it because they only looked at the graphs.
3. Cocktail party effect
When the researchers decided to study a phenomenon called the "cocktail party effect", they turned to patients with epilepsy, since they already had the necessary objects to observe - electrodes around their brain.
The electrodes were designed to record brain activity during seizures, but seven patients agreed to participate in the cocktail party study. It lies in the fact that in a very noisy environment, a person is able to concentrate on a strictly defined conversation. Scientists wanted to understand how the brain works in conditions of active noise interference.
Each subject listened to the same recording amid noises, unable to understand the speaker's speech. They then listened to a clear version of the same sentence, followed by another noisy recording. Incredibly, this time all the subjects understood the speaker. Brain activity showed that they weren't faking it.
During the first test (with a distorted recording), the areas of the brain responsible for hearing and speech remained inactive. But during the rest of the auditions, they worked. As it turns out, the reason for our ability to follow conversations at a noisy party lies in the incredible and lightning-fast plasticity of the brain.
As soon as the brain recognized the words, it began to react differently to the second distorted sentence. He fine-tuned the auditory and speech systems, which allowed him to determine the source of speech and filter out noise.
2. "Pink noise"
Among people with insomnia, the term "white noise" is sometimes synonymous with a restful night's rest. The brain's ability to ignore minor sounds - like fan noise - helps many fall asleep. But several independent studies have shown that there is something better for restful sleep - pink noise. “White noise” is sound with uniform power at all frequencies, while “pink” is a mixture of sounds in which the signal strength is inversely proportional to its frequency. A light in which the same conditions are met appears pink, which is what gave the noise a similar name.
Pleasant sounds of the wind, rustling leaves, or the sound of rain pounding on a roof can reduce brain activity. As a result, sleep becomes deeper and more restful. Chinese researchers found that "pink noise" lulls 75% of volunteers. When they tested naps, they found that those who slept to pink noise recovered 45 percent better than others.
For seniors, this can be good news. Aging leads to fragmentary sleep, which is responsible for memory loss. A group from the American University tested people over 60 years old, exposing some of them during sleep to "pink noise". In the morning, a memory test was performed. Those who have never been exposed to pink noise performed three times worse.
1. There are people who hate sound
For those who love pink noise or rock concerts, it may seem unrealistic to meet someone who cannot enjoy the sweet sounds. Those who sweat and suffer from heart palpitations when they hear certain noises.
While some might think these people are pretending, scientists in the UK have found that intolerance to sound is a real medical diagnosis. This disease is called misophonia and is associated with a brain abnormality. People with this condition have smaller and weaker frontal lobes than everyone else.
Two groups of people listened to sounds while scientists studied their brain activity. In the first group there were misophonia sufferers, in the second - no. Unpleasant sounds stimulated the central lobe of the brain in all subjects, regardless of the group. This area of the brain, among other things, is responsible for emotions and responses to a challenge to fight.
However, misophonics' brains reacted more intensely and produced physical symptoms of stress such as heart palpitations and sweating. Interestingly, the activity of the central lobe directly depends on the presence of anomalies in the frontal lobe.
Translated by Dmitry Oskin