Sound is sound waves that cause vibrations of tiny particles of air, other gases, and liquid and solid media. Sound can only arise where there is a substance, no matter what state of aggregation it is in. In vacuum conditions, where there is no medium, sound does not propagate, because there are no particles that act as distributors of sound waves. For example, in space. Sound can be modified, altered, turning into other forms of energy. Thus, sound converted into radio waves or electrical energy can be transmitted over distances and recorded on information media.
The movements of objects and bodies almost always cause fluctuations in the environment. It doesn't matter whether it's water or air. During this process, the particles of the medium to which the vibrations of the body are transmitted also begin to vibrate. Sound waves arise. Moreover, movements are carried out in forward and backward directions, progressively replacing each other. Therefore, the sound wave is longitudinal. There is never any lateral movement up and down in it.
Like any physical phenomenon, they have their own quantities, with the help of which properties can be described. The main characteristics of a sound wave are its frequency and amplitude. The first value shows how many waves are formed per second. The second determines the strength of the wave. Low-frequency sounds have low frequency values, and vice versa. The frequency of sound is measured in Hertz, and if it exceeds 20,000 Hz, then ultrasound occurs. There are plenty of examples of low-frequency and high-frequency sounds in nature and the world around us. The chirping of a nightingale, the rumble of thunder, the roar of a mountain river and others are all different sound frequencies. The amplitude of the wave directly depends on how loud the sound is. The volume, in turn, decreases with distance from the sound source. Accordingly, the further the wave is from the epicenter, the smaller the amplitude. In other words, the amplitude of a sound wave decreases with distance from the sound source.
This indicator of a sound wave is directly dependent on the nature of the medium in which it propagates. Both humidity and air temperature play a significant role here. In average weather conditions, the speed of sound is approximately 340 meters per second. In physics, there is such a thing as supersonic speed, which is always greater than the speed of sound. This is the speed at which sound waves travel when an aircraft moves. The plane moves at supersonic speed and even outruns the sound waves it creates. Due to the pressure gradually increasing behind the aircraft, a shock wave of sound is formed. The unit of measurement for this speed is interesting and few people know it. It's called Mach. Mach 1 is equal to the speed of sound. If a wave travels at Mach 2, then it travels twice as fast as the speed of sound.
There is constant noise in human daily life. The noise level is measured in decibels. The movement of cars, the wind, the rustling of leaves, the interweaving of people's voices and other sound noises are our daily companions. But the human auditory analyzer has the ability to get used to such noise. However, there are also phenomena that even the adaptive abilities of the human ear cannot cope with. For example, noise exceeding 120 dB can cause pain. The loudest animal is the blue whale. When it makes sounds, it can be heard over 800 kilometers away.
How does an echo occur? Everything is very simple here. A sound wave has the ability to be reflected from different surfaces: from water, from a rock, from walls in an empty room. This wave returns to us, so we hear secondary sound. It is not as clear as the original one because some of the energy in the sound wave is dissipated as it travels toward the obstacle.
Sound reflection is used for various practical purposes. For example, echolocation. It is based on the fact that with the help of ultrasonic waves it is possible to determine the distance to the object from which these waves are reflected. Calculations are made by measuring the time it takes for ultrasound to travel to a location and return. Many animals have the ability to echolocation. For example, bats and dolphins use it to search for food. Echolocation has found another application in medicine. During ultrasound examinations, a picture of a person’s internal organs is formed. The basis of this method is that ultrasound, entering a medium other than air, returns back, thus forming an image.
Why do musical instruments make certain sounds? Guitar strumming, piano strumming, low tones of drums and trumpets, the charming thin voice of a flute. All these and many other sounds arise due to air vibrations or, in other words, due to the appearance of sound waves. But why is the sound of musical instruments so diverse? It turns out that this depends on several factors. The first is the shape of the tool, the second is the material from which it is made.
Let's look at this using string instruments as an example. They become a source of sound when the strings are touched. As a result, they begin to vibrate and send different sounds into the environment. The low sound of any stringed instrument is due to the greater thickness and length of the string, as well as the weakness of its tension. And vice versa, the more tightly the string is stretched, the thinner and shorter it is, the higher the sound obtained as a result of playing.
It is based on the conversion of sound wave energy into electrical energy. In this case, the current strength and the nature of the sound are directly dependent. Inside any microphone there is a thin plate made of metal. When exposed to sound, it begins to perform oscillatory movements. The spiral to which the plate is connected also vibrates, resulting in an electric current. Why does he appear? This is because the microphone also has built-in magnets. When the spiral oscillates between its poles, an electric current is generated, which goes along the spiral and then to a sound column (loudspeaker) or to equipment for recording on an information medium (cassette, disk, computer). By the way, the microphone in the phone has a similar structure. But how do microphones work on landlines and mobile phones? The initial phase is the same for them - the sound of the human voice transmits its vibrations to the microphone plate, then everything follows the scenario described above: a spiral, which, when moving, closes two poles, a current is created. What's next? With a landline telephone, everything is more or less clear - just like in a microphone, the sound, converted into electric current, runs through the wires. But what about a cell phone or, for example, a walkie-talkie? In these cases, the sound is converted into radio wave energy and hits the satellite. That's all.
Sometimes conditions are created when the amplitude of vibrations of the physical body increases sharply. This occurs due to the convergence of the values of the frequency of forced oscillations and the natural frequency of oscillations of the object (body). Resonance can be both beneficial and harmful. For example, to get a car out of a hole, it is started and pushed back and forth in order to cause resonance and give the car inertia. But there have also been cases of negative consequences of resonance. For example, in St. Petersburg, about a hundred years ago, a bridge collapsed under soldiers marching in unison.
When we think about future technologies, we often overlook a field where incredible advances are happening: acoustics. Sound turns out to be one of the fundamental building blocks of the future. Science is using it to do incredible things, and you can be sure we'll hear and see a lot more in the future.
This system was developed as a more environmentally friendly alternative to modern refrigerators. Unlike traditional models that use chemical refrigerants to the detriment of the atmosphere, a thermoacoustic refrigerator works well with inert gases like helium. Since helium simply leaves the atmosphere if it suddenly enters it, the new technology will be more environmentally friendly than any other on the market. As this technology develops, its designers hope that thermoacoustic models will eventually surpass traditional refrigerators in all respects.
Like many technologies, this one was discovered by accident. Robert Soloff was working on ultrasonic sealing technology when he accidentally touched the tape dispenser on his desk with his probe. Eventually, the two parts of the dispenser were welded together, and Soloff realized that sound waves could bend around the corners and sides of hard plastic to reach the internal parts. Following the discovery, Soloff and his colleagues developed and patented an ultrasonic welding method.
Since then, ultrasonic welding has found wide application in many industries. From diapers to cars, this method is used everywhere to join plastics. Recently, they have even been experimenting with ultrasonic welding of seams on specialized clothing. Companies like Patagonia and Northface already use welded seams in their clothing, but only straight ones, and they are very expensive. Currently, hand sewing is still the simplest and most versatile method.
Security specialist Dragos Rui got the idea after he noticed something strange with his MacBook Air: after installing OS X, his computer spontaneously downloaded something else. It was a very powerful virus that could delete data and make changes at will. Even after uninstalling, reinstalling and reconfiguring the entire system, the problem remained. The most plausible explanation for the immortality of the virus was that it resided in the BIOS and remained there despite any operations. Another, less likely theory was that the virus used high-frequency transmissions between the speakers and microphone to manipulate data.
This strange theory seemed incredible, but was proven at least in terms of possibility when the German Institute found a way to reproduce this effect. Based on software developed for underwater communications, scientists developed a prototype of a malicious program that transferred data between laptops not connected to the Network using their speakers. In tests, laptops could communicate at a distance of up to 20 meters. The range could be expanded by linking infected devices into a network, similar to Wi-Fi repeaters.
The good news is that this acoustic transmission occurs extremely slowly, reaching speeds of 20 bits per second. While this is not enough to transmit large packets of data, it is sufficient to transmit information such as keystrokes, passwords, credit card numbers and encryption keys. Since modern viruses can do all this faster and better, it is unlikely that the new speaker system will become popular in the near future.
Doctors already use sound waves for medical procedures like ultrasounds and breaking up kidney stones, but scientists at Michigan State University have created an acoustic scalpel that is precise enough to separate even a single cell. Modern ultrasonic technologies make it possible to create a beam with a focus of several millimeters, but the new instrument has an accuracy of 75 by 400 micrometers.
The general technology has been known since the late 1800s, but the new scalpel is made possible by using a lens wrapped in carbon nanotubes and a material called polydimethylsiloxane, which converts light into high-pressure sound waves. When properly focused, sound waves create shock waves and microbubbles that exert pressure on a microscopic level. The technology was tested by removing a single ovarian cancer cell and drilling a 150-micrometer hole into an artificial kidney stone. The authors of the technology believe that it could finally be used to deliver drugs or remove small cancerous tumors or plaques. It can even be used for painless operations, since such an ultrasound beam can avoid nerve cells.
Since sound is simply the compression and expansion of gases in air, and therefore movement, it can be a viable source of energy. Scientists are experimenting with the ability to charge your phone while it's in use - while you're making a call, for example. In 2011, scientists in Seoul took zinc oxide nanorods sandwiched between two electrodes to extract electricity from sound waves. This technology could generate 50 millivolts simply from the noise of traffic. That's not enough to charge most electrical devices, but last year engineers in London decided to create a device that produces 5 volts - enough to charge a phone.
While charging phones with sounds may be good news for chatters, it could have a major impact on the developing world. The same technology that made the thermoacoustic refrigerator possible can be used to convert sound into electricity. The Score-Stove is a stove and refrigerator that extracts energy from the biomass fuel cooking process to produce small amounts of electricity, on the order of 150 watts. It's not much, but it's enough to provide energy to the 1.3 billion people on Earth who don't have access to electricity.
This device includes a microphone attached to the computer. When someone speaks into a microphone, the computer stores the speech as a recording on repeat, which is then converted into a barely audible signal. This signal is transmitted through a wire from the microphone to the body of anyone holding it, and produces a modulated electrostatic field that causes tiny vibrations if the person touches something. The vibrations can be heard if a person touches someone else's ear. They can even be transmitted from person to person if a group of people are in physical contact.
For best results, the algorithm requires that the number of frames per second in the video be higher than the frequency of the audio signal, which requires a high-speed camera. But, at worst, you can take a regular digital camera to determine, for example, the number of interlocutors in the room and their gender - perhaps even their identities. The new technology has obvious applications in forensics, law enforcement and spy warfare. With this technology, you can find out what is happening outside the window by simply taking out your digital camera.
Although this cape may not prevent eavesdropping, it can be useful in places where the object needs to be hidden from acoustic waves, such as a concert hall. On the other hand, the military has already had its eye on this camouflage pyramid, since it has the potential to hide objects from sonar, for example. Because sound travels underwater much the same way as through air, acoustic cloaking can make submarines undetectable.
By focusing two ultrasonic beams on a target, the object can be pushed towards the source of the beam, scattering the waves in the opposite direction (the object will appear to bounce on the waves). Although scientists have not yet been able to create the best type of wave for their technology, they continue to work. In the future, this technology could be used directly to control objects and fluids in the human body. For medicine it may turn out to be indispensable. Unfortunately, sound does not travel in the vacuum of space, so the technology is unlikely to be applicable to control spaceships.
The technology was originally designed to apply force to your skin to facilitate gesture control of certain devices. A mechanic with dirty hands, for example, might flip through the owner's manual. The technology needed to give touchscreens the feel of a physical page.
Because this technology uses sound to produce vibrations that reproduce the sensation of touch, the level of sensitivity can be changed. 4-Hz vibrations are like heavy raindrops, and 125-Hz vibrations are like touching foam. The only drawback at the moment is that these frequencies can be heard by dogs, but the designers say this can be fixed.
Now they are finalizing their device to produce virtual shapes like spheres and pyramids. True, these are not entirely virtual forms. Their work is based on sensors that follow your hand and generate sound waves accordingly. Currently, these objects lack detail and some precision, but designers say that one day the technology will be compatible with a visible hologram and the human brain will be able to put them together into one picture.
Based on materials from listverse.com
The idea of singing water came to the minds of the medieval Japanese hundreds of years ago and reached its peak by the mid-19th century. Such an installation is called “shuikinkutsu”, which loosely translated means “water harp”:
According to the video, shukinkutsu is a large empty vessel, usually installed in the ground on a concrete base. There is a hole in the top of the vessel through which water drips inside. A drainage tube is inserted into the concrete base to drain excess water, and the base itself is made slightly concave so that there is always a shallow puddle on it. The sound of the drops reflects off the walls of the vessel, creating a natural reverberation (see picture below).
Shuikinkutsu in section: a hollow vessel on a concave concrete base at the top, a drainage tube to drain excess water, a backfill of stones (gravel) at the base and around it.
Shuikinkutsu have traditionally been an element of Japanese garden design and rock gardens in the spirit of Zen. In the old days, they were placed on the banks of streams near Buddhist temples and houses for the tea ceremony. It was believed that after washing one’s hands before the tea ceremony and hearing magical sounds from underground, a person tunes into an elevated mood. The Japanese still believe that the best, purest-sounding shuikinkutsu should be made from solid stone, although this requirement is not observed these days.
By the middle of the twentieth century, the art of constructing shuikinkutsu was almost lost - only a couple of shuikinkutsu remained throughout Japan, but in recent years interest in them has experienced an extraordinary rise. Today they are made from more affordable materials - most often from ceramic or metal vessels of a suitable size. The peculiarity of the sound of shuikinkutsu is that in addition to the main tone of the drop inside the container, due to the resonance of the walls, additional frequencies (harmonics) arise, both above and below the main tone.
In our local conditions, you can create shuikinkutsu in different ways: not only from a ceramic or metal container, but also, for example, by laying it directly in the ground from red brick along method of making Eskimo igloos or cast from concrete according to t technology for creating bells– these options will sound closest to all-stone shuikinkutsu.
In the budget version, you can get by with a piece of large-diameter steel pipe (630 mm, 720 mm), covered at the top end with a lid (thick metal sheet) with a hole for water drainage. I would not recommend using plastic containers: plastic absorbs some sound frequencies, and in shuikinkutsu you need to achieve their maximum reflection from the walls.
Prerequisites:
1. the entire system must be completely hidden underground;
2. The base and filling of the side sinuses must be made of stone (crushed stone, gravel, pebbles) - filling the sinuses with soil will negate the resonant properties of the container.
It is logical to assume that the height of the vessel—more precisely, its depth—is of decisive importance in the installation: the faster a drop of water accelerates in flight, the louder its impact on the bottom will be, the more interesting and fuller the sound will be. But there is no need to reach the point of fanaticism and build a missile silo - a height of the container (a piece of metal pipe) of 1.5-2.5 times the size of its diameter is quite sufficient. Please note that the wider the volume of the container, the lower the sound of the main tone of the shuikinkutsu will be.
Physicist Yoshio Watanabe studied the characteristics of the reverberation of suikinkutsu in the laboratory; his study “Analytic Study of Acoustic Mechanism of “Suikinkutsu”” is freely available on the Internet. For the most meticulous readers, Watanabe offers, in his opinion, the optimal dimensions of traditional shukinkutsu: a ceramic vessel with a wall 2 cm thick, bell-shaped or pear-shaped, a free drop height of 30 to 40 cm, a maximum internal diameter of about 35 cm. But the scientist fully allows any arbitrary dimensions and shapes.
You can experiment and get interesting effects if you make a shuikinkutsu like a pipe within a pipe: insert a pipe of a smaller diameter (630 mm) and a slightly smaller height inside a steel pipe of a larger diameter (for example, 820 mm), and additionally cut several holes in the walls of the inner pipe at different heights with a diameter of approximately 10-15 cm. Then the empty gap between the pipes will create additional reverberation, and if you are lucky, then an echo.
A lightweight option: during pouring, insert a pair of thick metal plates 10-15 centimeters wide and a height higher than half the internal volume of the container vertically and slightly at an angle into the concrete base - due to this, the area of the internal surface of the shukinkutsu will increase, additional sound reflections will arise, and, accordingly, a little The reverberation time will increase.
You can modernize the shuikinkutsu even more radically: if you hang bells or carefully selected metal plates in the lower part of the container along the axis of falling water, then you can get a euphonious sound from the drops hitting them. But keep in mind that in this case the idea of shuikinkutsu, which is to listen to the natural music of water, is distorted.
Now in Japan, shuikinkutsu is performed not only in Zen parks and private properties, but even in cities, in offices and restaurants. To do this, a miniature fountain is installed near the shuikinkutsu, sometimes one or two microphones are placed inside the vessel, then their signal is amplified and fed to speakers disguised nearby. The result looks something like this:
A good example to follow.
Shuikinkutsu enthusiasts have released a CD containing recordings of various Shuikinkutsu created in different parts of Japan.
The idea of shuikinkutsu found its development on the other side of the Pacific Ocean:
This American “wave organ” is based on conventional long-length plastic pipes. Installed with one edge exactly at the level of the waves, the pipes resonate from the movement of water and, due to their bending, also act as a sound filter. In the Shukinkutsu tradition, the entire structure is hidden from view. The installation is already included in tourist guides.
The next British device is also made from plastic pipes, but is not intended to generate sound, but to change an existing signal.
The device is called the Organ of Corti and consists of several rows of hollow plastic pipes fixed vertically between two plates. Rows of pipes act as a natural sound filter similar to those installed in synthesizers and guitar “gadgets”: some frequencies are absorbed by the plastic, others are repeatedly reflected and resonate. As a result, the sound coming from the surrounding space is transformed randomly:
It would be interesting to put such a device in front of a guitar amp or any speaker system and listen to how the sound changes. Truly, “...everything around is music. Or he can become one with the help of microphones” (American composer John Cage). …I’m thinking of creating a shuikinkutsu in my country this summer. With lingam.
3.3. Household noise and vibration
Noise is a combination of sounds of varying intensity and frequency that occur during mechanical vibrations.
Currently, scientific progress has led to the fact that noise has reached such high levels that they are no longer just unpleasant to the ear, but also dangerous to human health.
There are two types of noise: airborne (from the source to the place of perception) and structural (noise from the surface of vibrating structures). Noise in air travels at a speed of 344 m/s, in water – 1500, in metal – 7000 m/s. In addition to the speed of propagation, noise is characterized by pressure, intensity and frequency of sound vibrations. Sound pressure is the difference between the instantaneous pressure in a medium in the presence of sound and the average pressure in its absence. Intensity is the flow of energy per unit time per unit area. The frequency of sound vibrations is in a wide range from 16 to 20,000 hertz. However, the basic unit of sound rating is sound pressure level, measured in decibels (dB).
Recently, the average noise level in large cities has increased by 10–12 decibels. The reason for the noise problem in cities is the contradiction between transport development and city planning. High noise levels are observed in residential buildings, schools, hospitals, recreational areas, etc.; the consequence of this is an increase in the nervous tension of the population, a decrease in efficiency, and an increase in the number of diseases. Even at night in an apartment in a quiet city, the noise level reaches 30–32 dB.
Currently, it is believed that noise up to 30–35 dB is acceptable for sleep and rest. When working at an enterprise, noise intensity is allowed within the range of 40–70 dB. For a short time, the noise can rise to 80–90 dB. At an intensity of more than 90 dB, noise is harmful to health and the more harmful it is, the longer its exposure. Noise of 120–130 dB causes ear pain. At 180 dB it can be fatal.
As an environmental factor in the home, noise sources can be divided into external and internal.
External is primarily the noise of city transport, as well as industrial noise from enterprises located near the house. In addition, it could be the sounds of tape recorders that neighbors turn on at full volume, violating the “acoustic culture.” External sources of noise are also sounds, for example, from a store or post office located below, the sounds of airplanes taking off or landing, as well as electric trains.
External noise, perhaps, should include the noise of the elevator and the constantly slamming front door, as well as the crying of a neighbor’s child. Unfortunately, the walls of residential buildings are usually poorly soundproofed. Internal noises are usually inconsistent (except for sounds produced by television or playing musical instruments). Of these variable noises, the most unpleasant is the noise of incorrectly installed or outdated plumbing fixtures and the noise of a working refrigerator, which is automatically turned on from time to time. If there is no soundproofing mat under the refrigerator or shelves are not secured inside, then this noise can be quite significant - short-term, but strong enough to ruin a person’s mood. A person is disturbed by the noise from a working vacuum cleaner or washing machine if the design of these devices is outdated and does not meet accepted requirements, including the permissible noise level.
Renovation in your or your neighbor’s apartment is a cacophony of sounds. Particularly unpleasant are the sounds of an electric drill (modern concrete walls are very difficult to penetrate) and the sharp sounds of a hammer blow. Among internal noises, the sounds of radio devices occupy a special place. In order for music to be enjoyable (what kind of music is another matter), its level should not be higher than 80 dB, and its duration should be relatively short. From an environmental point of view, it is unacceptable if the TV or radio is turned on at high volume and runs for a long time. An acquaintance of the author told his neighbor, who was constantly talking about something, that he loved the radio because he could always turn it off. Constant use of the player is dangerous. Not only do the sounds of the player disrupt the functioning of the eardrums, but they also create circular magnetic fields around the head, disrupting the functioning of the brain.
Each person perceives noise individually; it depends on the person’s age, state of health and environmental conditions. The organs of hearing can adapt to constant or repeated noise, but this adaptability cannot protect it from pathological changes in hearing, but only temporarily postpones the timing of these changes.
The damage that loud noise causes to hearing depends on the pitch and frequency of sound vibrations and the nature of their changes. When hearing deteriorates, a person begins to hear high sounds worse first, and then low ones. Exposure to noise for a long time can negatively affect not only hearing, but also cause other diseases in the human body. Excessive noise can cause nervous exhaustion, mental depression, peptic ulcers, and disorders of the cardiovascular system. Elderly people feel the effects of noise especially strongly. People involved in mental work experience a greater impact of noise than physical work, which is associated with greater fatigue of the nervous system during mental work.
Household noise significantly impairs sleep. Intermittent, sudden noises are especially unfavorable. Noise reduces the duration and depth of sleep. A noise of 50 dB increases the time it takes to fall asleep by an hour, sleep becomes more shallow, and after waking up you feel tired, headache and palpitations.
Sound waves with a frequency below 16 hertz are called infrasound, and above 20,000 Hz - ultrasound; they are not audible, but they also affect the human body; for example, a household fan can be a source of infrasound, and the squeak of mosquitoes can be an ultrasound source. Sound reduces not only hearing acuity (as is commonly believed), but also visual acuity, therefore, a vehicle driver should not constantly listen to music while driving. Intense sound increases blood pressure; People do the right thing by isolating sick people in the house from noise. Besides, the noise just causes normal fatigue. Work performed in conditions of noise pollution in the environment requires more energy than work in silence, i.e. it becomes more difficult. If the noise is constant in time and frequency, it can cause neuritis, while at the beginning sensitivity to sounds of a certain frequency is removed: at 130 dB ear pain occurs, at 150 dB - hearing damage at any frequency. The author's neighbor lost almost all her hearing after working in a textile factory for 25 years.
To protect people from the harmful effects of noise, it is necessary to standardize its intensity, spectral composition, duration of action and other noise characteristics.
During hygienic standardization, the acceptable noise level is set at a level at which no changes in the physiological parameters of the human body are detected for a long time.
For people in creative professions, the recommended noise level is no more than 50 dBA (dBA is the equivalent value of the sound level taking into account its frequency); for highly qualified work related to measurements - 60 dBA; for work requiring concentration – 75 dBA; other types of work – 80 dBA.
These levels are determined for production, but it is not recommended to exceed them at home.
Sanitary standards for permissible noise in the premises of residential and public buildings and in residential areas establish standard sound pressure levels and sound levels for the premises of residential and public buildings, for the territories of microdistricts, hospitals, sanatoriums, and recreation areas.
An important role in the fight against noise pollution belongs to the control system and methods for measuring the actual noise level. Currently, in large cities of Russia, noise monitoring is carried out in certain points of the city, and noise maps are compiled. To assist the sanitary service, special permanent commissions have been formed to combat urban noise.
The establishment of sanitary standards for acceptable levels and the nature of noise makes it possible to develop technical, planning and other urban planning measures aimed at creating a favorable noise regime.
The presence of standards and knowledge of the actual situation in relation to places where noise intensity occurs and sources make it possible to plan measures to combat noise and impose the necessary requirements on enterprises, construction sites and various types of transport.
To measure the noise level in everyday life, it is best to recommend the small-sized sound level meter ShM-1. This device can be purchased at a hardware store or at environmental companies (for example, Ecoservice). The procedure for operating the devices is given in the accompanying documentation.
There are a number of options for reducing noise levels in cities and towns. General measures to combat intense noise in production include the design of low-power machines and the use of silent or low-noise technological processes; development and use of more effective insulating materials in the construction of industrial and residential buildings; installation of noise barriers of various types, etc.
Various urban planning measures offer great opportunities to protect the population from noise. These include: increasing the distance between the source and the protected object; use of special noise protection strips for landscaping; various planning techniques, rational placement of noisy and protected objects in microdistricts.
Green strips between the roadway and residential buildings contribute to the concentration of noise levels (and carbon oxides).
The fight against household noise can only be successful when a person demonstrates maximum “acoustic culture.”
What methods of dealing with household noise can be recommended to residents?
Just as for other types of radiation, methods of protecting humans from the harmful effects of noise are protection by time and distance, reducing the power of the sound source, insulation and shielding. But here, as with no other influences, social protection also plays a role, or rather, compliance with the norms of people living together.
In terms of the importance of the noise protection method, it seems that we need to start by reducing its power. As a rule, external noise cannot be reduced on your own, unless you move to another, quieter area of the city. But not all city residents can escape the noise of traffic (including, for example, the noise of airplanes and trains). It is easier to deal with sound hooligans (young lovers of loud music, usually located in children's playgrounds) up to the point of calling the police after 11 pm. The exception is the graduation party, when at the end of May, throughout the night, according to an established tradition, the sounds of modern music are heard with the volume of a taking off airliner (more than 100 dB). Exceptions include explosions of firecrackers on holiday nights, especially New Year's Eve. But here an ordinary resident will not be able to do anything, no matter how tired he is during the day. The only way out is to go outside and launch the rocket yourself. Elevator noise can be partially reduced by contacting the housing office with a request to carry out repairs and maintenance of the elevator's power equipment. If the home is located on the top floor, noise and vibration from the elevator can be protected only by shielding (soundproofing) the wall adjacent to the elevator. The impact of external door slamming can be prevented by installing a modern, low-noise door or, in the old-fashioned way, by gluing rubber gaskets to it, for example. You can protect yourself from the crying of a neighbor’s child or from the results of family squabbles in three ways: hang a carpet on an adjacent wall (although this is not fashionable), move the bedroom to a quiet room (i.e. create a quiet relaxation area) or use an individual means of protection against noise - earplugs (or cotton swabs in the ears). Now you can buy inexpensive and very effective foreign earplugs in workwear stores.
It’s easier with internal noise: electrical appliances must be modern (i.e., quiet). But, unfortunately, they are often very expensive. The refrigerator, washing machine and vacuum cleaner - indispensable attributes of technological progress - should, if possible, be turned on for a short time, at minimum power and away from sick children. This is protection by time, distance and reduction in the power of the wave radiation source. It is also advisable to install the refrigerator and washing machine on a rubber mat, which will protect residents not only from noise and vibration, but will also provide an additional degree of electrical insulation. A serious noise problem in the home is radio equipment (TVs, radios, radios). But here the owners can not only weaken the attack, for example, of children on their eardrums, but also promptly and radically eliminate the source of noise by turning it off. It depends on the “acoustic culture” of the apartment’s residents.
Some older people cannot tolerate loud, harsh sounds. For example, a disabled veteran of the Second World War, one of the first to use Katyushas, takes knocks very painfully, declaring that he heard them too much when mines exploded.
As for plumbing, unfortunately, taps often leak (which also causes economic damage to the state, since in Russia water consumption is 2–2.5 times higher than abroad, and we still cannot switch to using meters water). Foreign ball valves are very convenient, they make almost no noise and do not leak. The owner must carefully monitor the plumbing and prevent breakdowns. The noise of water in the drain tank is successfully reduced by installing a rubber hose on the float regulator, but most often it is blown off by a stream of water, and residents, without looking into the tank, wonder why the drain has become so noisy that it wakes up household members at night. It is inadvisable to open taps unnecessarily, both because it is noisy and because the tap vibrates, and therefore drinking water is overused. The noise in the pipes of the building is eliminated with difficulty and only by specialists and mainly irritates the residents of the upper floors. To solve this problem, sometimes it is enough to contact the plumbers of the housing office so that they can eliminate air locks in the water supply network.
As for protection by distance, it is advisable to move the refrigerator into the hallway, and the washing machine into the bathroom, which, unfortunately, is not always possible when the kitchen, bathroom and hallway are small.
The apartment must have at least one room without radiation (including a room without noise) - this quiet and safe zone will increase the lifespan of people living in the apartment.
Apartment renovation is, of course, a force majeure event (apartment-scale emergency). People whose houses are being renovated are noticeably different from other people: they are nervous, tired and pale. The noise of repairs (the roar and vibration of a drill, the knocking of hammers, the noise of parquet machines) contributes to this condition. Fortunately, this emergency situation is relatively short-lived.
Unlike other radiations that pollute the household environment, noise can be beneficial and even comfortable. The author means the sound of sea waves, winds in the forest, birdsong and the sound of rain if you are in shelter, and, of course, music (soft, melodic and best of all classical).
I remember one pedagogical experiment conducted by the author in college. When replacing a lesson on world culture, the author allowed students to do their own thing (copying notes, quiet conversations, doing crossword puzzles), but quietly, at 40 dB, turned on a tape recorder with a recording of a Mozart symphony. After the lesson, several students asked to rewrite this recording, despite their love of pop music.
In nature and in production, there is another type of wave - vibration. Fortunately, it is not typical for housing, except for the vibration of a refrigerator, washing machine or fan. It is much worse if there is a thermal power plant or a shallow metro station nearby. The main method of combating vibration is the use of dampers (vibration absorbers), which can be carpets, rugs and rubber mats.
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Atmospheric acoustics studies mainly the propagation of sound in a free atmosphere. Experience has established that sound travels much further downwind than against the direction of the wind or when there is no wind. This is explained by the transfer of wind sound (it is known that the speed of air movement in the wind is insignificant relative to the speed of sound), and thus the speed of air movement above the surface of the earth is noticeably less than at a certain height. In this regard, the sound waves in the direction of the wind are slightly inclined with their upper parts forward, and therefore the sound is pressed to the ground, which creates an amplification of the sound. Sound waves traveling against the wind fly away, and therefore the sound beam moves away from the ground.
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In general, distortion of the path of a sound beam, due to its different sound refraction in the air, caused by changes in temperature and wind speed at different altitudes, can lead to the sound source being surrounded by a zone of silence, beyond which the sound returns.
The propagation of sound in free air has a number of features. Due to which in thermal conductivity and viscosity in the atmosphere, absorption sound waves will be higher in frequency in sound and lower in density in air. Consequently, these sharp sounds or explosions become muffled over greater distances. The audible sounds at very low frequencies (known as infrasound) have periods of a few seconds to a few minutes that are not greatly attenuated and can travel thousands of kilometers and can even circle the earth several times. This is necessary to be able to detect nuclear explosions, which are a powerful source for such waves.
These are important problems in atmospheric acoustics related to the phenomena that occur during the propagation of sound in the atmosphere, which from an acoustic point of view is the movement of an inhomogeneous medium. Temperatures and densities in the atmosphere decrease with increasing altitude; At higher altitudes the temperature rises again. With these regular irregularities, they are variations in temperature and wind, which depend on meteorological conditions, as well as random turbulent pulsations from various.
Because speed The wind will be controlled by the air temperature, then the sound is "carried" by the wind, so that the heterogeneity mentioned has a stronger effect on sound propagation. Flexible sound rays-refractions which are happening from sound, as a result of which sound-ray deflects and can be returned to the earth's surface, thus forming an acoustic audibility zone and a silence zone; sound dispersion and attenuation occur in turbulent anomalies, strong absorption at high altitudes, etc.
Atmospheric acoustics is necessary for solving a complex inverse problem in acoustic sound from the atmosphere. The distribution in temperature and wind at high altitudes will be obtained from measurements, but in time and direction upon arrival from sound waves created by the ground level of the explosion or from the explosion.
To obtain research on turbulence, you need to know the temperature and speed winds which are determined by measuring the time propagation of sound over short distances; to achieve the required precision ultrasonic frequencies that will .
Problem distributionindustrial noise, in particular, which originate from the shock waves produced by the movement of a supersonic jet, has already become extremely important. If atmospheric conditions are favorable for focusing these waves, then the pressure at the first level can reach values that are dangerous to human health.
Various sounds of natural origin are also observed in the atmosphere. Long rumbles of thunder occur due to the large length of the lightning discharge and therefore when the sound waves are refracted they travel along different paths and arrive with different delays. Some geophysical phenomena such as auroras, magnetic storms, strong earthquakes, hurricanes, and sea waves are sources of sound, in particular infrasonic waves. Their research is important not only for geophysics, for example, for timely storm warnings. Various sound noises that are produced either by the collision of vortices with various objects (whistle due to the wind) or by the vibrations of certain objects in the air flow (whistle of wires, rustling of leaves, and so on).
Particularly remarkable are the phenomena observed during huge explosions, such as, for example, in Moscow in 1920. The sound of the explosion was heard at 50 km, then at 50 and up to 160 km there was a zone of silence. Then the sound was heard again. Such phenomena are explained by the reflection of sound from the boundary, where air begins to be noticeably absent, and the so-called hydrogen atmosphere begins. These questions are not yet final.
The phenomenon of echo, which is often multiple, is explained by the reflection of sound from large surfaces, for example, forests, mountains, walls of a large building, and the like. To have more or less correct reflection of waves of any kind (sound, light, on the surface of water), it is necessary that the roughness of the reflecting surface have dimensions that are small compared to the wavelength of the energy incident on them, and that the dimensions of the reflecting surface itself be large compared to the length waves. That is why a wall of frequent and dense trees reflects sounds well, the wavelength of which is usually about 0.5-2 m.
Atmospheric acoustics provides the knowledge and tools to describe the propagation of sound in the atmosphere. To address outdoor noise problems, particularly noise from aircraft, road vehicles, trains and wind turbines, sound propagation is an important link between source and receiver. It is part of the functional chain between noise effects and noise effects on people (eg sleep disturbance, irritation, health impairment). Although modern noise forecasting tools are governed by national and international standards (eg ISO), scientific models of sound propagation are much more complex and capable of describing meteorological and topographic influences in detail. However, these models are quite complex in terms of computational resources, both in terms of time and storage. The use of these models is therefore limited to scientific applications (studies of processes and relationships, for example to obtain parameterizations) and selected practical problems.
However, the science of atmospheric acoustics still has great potential for new applications and further development. The availability of more powerful computers in the future will open up applications for larger ranges and higher frequencies. A further expansion of applicability is expected from the introduction of improved numerical .
Some of the material is translated from: https://encyclopedia2.thefreedictionary.com/Atmospheric+Acoustics
https://link.springer.com/chapter/10.1007/978-3-642-30183-4_13
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