Decibel: what is it? Noise levels in decibels: acceptable standards Noise is measured in decibels

There are different noise levels and permissible standards, exceeding which poses a great danger to human hearing.

How is noise measured?

Noise levels, like sounds, are measured in decibels (dB). According to the law of the Russian Federation, there are established standards that cannot be exceeded. In the daytime - no more than 55 decibels, at night - no higher than 45 dB. These are maximum permissible values, since their increase has a negative impact on human health. The nervous system is mainly affected and headaches occur.

Why are high-pitched sounds dangerous?

Noise levels may vary. Some do not exceed the norms established by law and do not interfere with human life. During the daytime, a higher sound level is allowed, but it also has its own limits in decibels. If the norm is exceeded, the person may feel nervous and irritable. Reactions are slowed down, productivity and intelligence decrease.

Noise above 70 decibels can cause hearing impairment. Especially loud sounds have a strong impact on the health of children, disabled people and the elderly. According to studies of the influence of noise on humans, the reaction of the nervous system to an increase in permissible background noise standards begins at 40 decibels. Sleep is disturbed already at 35 dB.

Strong changes in the nervous system occur at noise levels of 70 decibels. In this case, a person may develop mental illness, hearing and vision deteriorate, and even the blood composition may change negatively.

For example, in Germany, almost twenty percent of workers work in noise levels between 85 and 90 decibels. And this led to increased cases of hearing loss. Constant noise that exceeds the norm entails, at a minimum, drowsiness, fatigue and irritation.

What happens to hearing when exposed to noise?

Prolonged or excessively loud background noise can damage a person's hearing system. The most dangerous thing in this case is rupture of the eardrums. Accordingly, hearing decreases or complete deafness occurs. In the worst case scenario, with a loud explosion, the sound level of which reaches 200 decibels, a person dies.

Norms

The maximum noise level in a residential area (at any time of the day) is set in accordance with sanitary requirements. Sound over 70 decibels and higher is harmful not only to the psychological, but also to the physical state of a person. At enterprises, the noise level is regulated in accordance with sanitary standards and hygienic requirements established in the Russian Federation.

The optimal background noise level is considered to be 20 decibels. For comparison, city noise averages 30 to 40 dB. And the maximum permissible for airliners is 50 dB above the ground. Now on many city streets noise levels reach 65 to 85 decibels. But the most common indicators are from 70 to 75 dB. And this is at a standard of 70 dB.

High noise level (dB) is 90. It causes headaches, increases blood pressure, etc. Areas with high noise levels include residential areas near airports, industrial enterprises, etc. In construction sites, the permitted level of increased noise is not must exceed 45 decibels.

The main sources of noise are cars, aviation and railway transport, industrial production, etc. The average background noise on the roads of large cities is from 73 to 83 decibels. And the maximum is from 90 to 95 dB. In houses located along highways, noise can reach from 62 to 77 decibels.

Although, according to sanitary standards, background noise should not exceed 40 dB during the day, and 30 dB at night. According to the Ministry of Transport, approximately thirty percent of the population lives in noise discomfort zones in the Russian Federation. And from three to four percent of citizens are under the aviation sound background.

Low-intensity noise levels from urban traffic that can be heard in residential areas are approximately 35 decibels. This does not cause physiological changes in people. At a sound level of 40 decibels, after ten minutes a change in hearing sensitivity begins. Under the influence of constant noise for fifteen minutes, sensations return to normal. At 40 dB, the duration of restful sleep is slightly disrupted.

In factory production where the press operates, a special muffler is installed on it. As a result, noise is reduced from 95 to 83 decibels. And it becomes below the established sanitary standards for production.

But mostly people suffer from car noise. In cities where there is heavy traffic, the sound background is slightly higher than normal. When powerful trucks pass, the noise reaches its maximum value - from 85 to 95 decibels. But on average in large cities the excess of the permissible norm ranges from 5 to 7 decibels. And only in private sectors does the noise level meet accepted standards.

Technological progress causes an increase in artificial sound background, which in this case becomes harmful to humans. In some industries, the noise level in the room reaches 60 to 70 decibels or higher. Although the norm should be a value of 40 dB. All operating mechanisms create a lot of noise, spreading over a long distance.

This is especially noticeable in the mining and metallurgical industries. In such industries, the noise reaches 75 to 80 decibels. From explosions and the operation of turbojet engines - from 110 to 130 dB.

What do sanitary noise standards include?

Sanitary noise standards include many factors. The frequency characteristics, duration and time of exposure to a loud background sound, and its character are measured. Measurements are carried out in decibels.

The standards are based on the characteristics of what level of noise, even over a long period of time, does not cause negative changes in the human body. During the day it is no more than 40 decibels, and at night it is no higher than 30 dB. The permissible limit of transport noise is from 84 to 92 dB. And over time, the established background noise standards are planned to be lowered further.

How to determine noise level?

At night, getting rid of loud noise is quite easy. You can call a local police officer or a police squad. But in the daytime, determining the noise level is much more problematic. Therefore, there is a special examination. A special sanitary and epidemiological commission from Rospotrebnadzor is called. And the outgoing noise is recorded in decibels. After the measurements, a report is drawn up.

Noise standards during construction

When constructing residential buildings, developers are required to provide the premises with good sound insulation. The noise should not be more than 50 decibels. This applies to sounds transmitted through the air (working TV, neighbors talking, etc.).

Comparative indicators of permissible noise

Short-term exposure to loud sounds up to 60 decibels is not dangerous for humans. In contrast to systematic noise, which disrupts the nervous system. The following describes the noise levels (in dB) from various sources:

• human whisper - from 30 to 40;
• refrigerator operation - 42;
• elevator cabin movement - from 35 to 43;
• Breezer ventilation - from 30 to 40;
• air conditioning - 45;
• noise of a flying airliner - 140;
• playing the piano - 80;
• noise of the forest - from 10 to 24;
• flowing water - from 38 to 58;
• noise of a working vacuum cleaner - 80;
• colloquial speech - from 45 to 60;
• supermarket noise - 60;
• car horn - 120;
• cooking on the stove - 40;
• noise of a motorcycle or train - from 90;
• repair work - 100;
• dance music in nightclubs - 110;
• baby crying - from 70 to 80;
• Lethal noise level for humans is 200.

From the list it is clear that many sounds that a person encounters every day exceed the permissible noise level. Moreover, only natural sounds are listed above, which are almost impossible to avoid. And if additional decibels are added, then the sound threshold established by sanitary standards is sharply exceeded.

Therefore, rest is important. After working in industries where noise levels are off the charts, it is necessary to restore your hearing. To do this, it is enough to spend as much time as possible in relaxing, quiet places. Outdoor trips are good for this.

How to measure noise in decibels?

The permissible noise level can be measured independently using special items - noise meters. But they are very expensive. And the recording of sound levels is carried out only by specialists, without whose conclusion the acts will be invalid.

As mentioned above, aggressive noise exposure sometimes leads to ruptured eardrums. For this reason, hearing deteriorates, sometimes to the point of complete deafness. Although the eardrum can recover, the process is very long and depends on the severity of the damage.

For this reason, it is recommended to avoid prolonged exposure to noise. From time to time you need to give your ears a rest: be in complete silence, go to the village (dacha), do not listen to music, turn off the TV. But first of all, it is advisable to abandon all kinds of portable music players with headphones.

All this will help preserve our precious hearing, which will always serve faithfully. In addition, silence helps the eardrums recover after injury.

In the last article we touched on the topic of cleaning ears with cotton swabs. It turned out that, despite the prevalence of such a procedure, self-cleaning of the ears can lead to perforation (rupture) of the eardrum and a significant decrease in hearing, up to complete deafness. However, improper ear cleaning is not the only thing that can damage our hearing. Excessive noise that exceeds sanitary standards, as well as barotrauma (injuries associated with pressure changes) can also lead to hearing loss.

To have an idea of ​​the danger that noise poses to hearing, it is necessary to familiarize yourself with the permissible noise standards for different times of the day, as well as find out what noise level in decibels certain sounds produce. In this way, you can begin to understand what is safe for your hearing and what is dangerous. And with understanding comes the ability to avoid the harmful effects of sound on hearing.

According to sanitary standards, the permissible noise level that does not harm hearing even with prolonged exposure to the hearing aid is considered to be: 55 decibels (dB) during the daytime and 40 decibels (dB) at night. Such values ​​are normal for our ear, but, unfortunately, they are very often violated, especially within large cities.

Noise level in decibels (dB)

Indeed, the normal noise level is often significantly exceeded. Here are examples of just some of the sounds we encounter in our lives and how many decibels (dB) these sounds actually contain:

• Spoken speech ranges from 45 decibels (dB) to 60 decibels (dB), depending on the volume of the voice;
• Car horn reaches 120 decibels (dB);
• Heavy traffic noise – up to 80 decibels (dB);
• Baby crying – 80 decibels (dB);
• Operation noise of various office equipment, vacuum cleaner - 80 decibels (dB);
• Noise of a running motorcycle, train - 90 decibels (dB);
• The sound of dance music in a nightclub is 110 decibels (dB));
• Airplane noise - 140 decibels (dB);
• Noise from repair work – up to 100 decibels (dB);
• Cooking on a stove - 40 decibels (dB);
• Forest noise from 10 to 24 decibels (dB);
• Lethal noise level for humans, explosion sound - 200 decibels (dB)).

As you can see, most of the noises that we encounter literally every day significantly exceed the permissible threshold. And these are just natural noises that we cannot do anything about. But there is also noise from TV and loud music, to which we expose our hearing aids. And with our own hands we cause enormous harm to our hearing.

What noise level is harmful?

If the noise level reaches 70-90 decibels (dB) and continues for quite a long time, then such noise with prolonged exposure can lead to diseases of the central nervous system. And prolonged exposure to noise levels of more than 100 decibels (dB) can lead to significant hearing loss, including complete deafness. Therefore, we get much more harm from loud music than pleasure and benefit.

What happens to hearing when exposed to noise?

Aggressive and prolonged noise exposure to the hearing aid can lead to perforation (rupture) of the eardrum. The consequence of this is decreased hearing and, as an extreme case, complete deafness. And although perforation (rupture) of the eardrum is a reversible disease (i.e., the eardrum can recover), the recovery process is long and depends on the severity of the perforation. In any case, treatment of perforation of the eardrum is carried out under the supervision of a doctor, who chooses a treatment regimen after examination.

Chapter from the book “Noise” by English engineer Rupert Taylor, R. Taylor “Noise”

Nowadays, everyone has already heard something about “decibels,” but almost no one knows what it is. The decibel seems to be something of an acoustic equivalent of a "candle" - a unit of luminous intensity - and seems to be associated with the ringing of bells (bell means bell, bell in English). However, this is not at all true: the decibel got its name in honor of Alexander Graham Bell, the inventor of the telephone.

The decibel is not only not a unit of measurement of sound, it is not a unit of measurement at all, at least in the same sense as, for example, volts, meters, grams, etc. If you like, you can even measure the length of hair in decibels, which is absolutely impossible do it in volts. Apparently, this all sounds a little strange, so let's try to clarify. Probably no one will be surprised if I say that the distance from London to Inverness is twenty times greater than from my home to London. I can express any distance by comparing it with the distance from my house to London, say to Piccadilly Circus. The distance from London to John-o-Trots is twenty-six times greater than this last distance, and to Australia 500 times. But this does not mean that Australia is 500 units away from anything. All numbers given express only ratios of magnitudes.

One of the measurable characteristics of sound is the amount of energy it contains; The sound intensity at any point can be measured as the flow of energy per unit area and expressed, for example, in watts per square meter (W/m2). When trying to record the intensity of ordinary noise in these units, difficulties immediately arise, since the intensity of the quietest sound that can be perceived by a person with the most acute hearing is approximately 0.000 000 000 001 W/m 2 . One of the loudest sounds that we encounter, not without the risk of harmful consequences, is the noise of a jet aircraft flying at a distance of about 50 m. Its intensity is about 10 W/m2. And at a distance of 100 m from the Saturn rocket launch site, the sound intensity noticeably exceeds 1000 W/m2. It is obvious that it is very difficult to handle numbers expressing sound intensities that lie over such a wide range, regardless of whether we represent them in units of energy or even in the form of ratios. There is a simple, although not entirely obvious, way out of this difficulty. The intensity of the weakest audible sound is 0.000 000 000 001 W/m2. Mathematicians will prefer to write this number this way: 10 -12 W/m2. If this notation is unusual for anyone, let us recall that 10 2 is 10 squared, or 100, and 10 3 is 10 cubed, or 1000. Similarly, 10 -2 means 1/10 2, or 1/100, or 0, 01, and 10 -3 is 1/10 3, or 0.001. Multiplying any number by 10 x means x times multiplying it by 10.

Trying to find the most convenient way to express sound intensities, let's try to present them in the form of ratios, taking the value 10 -12 W/m2 as the reference intensity. At the same time, we will note how many times the reference intensity must be multiplied by 10 in order to obtain the specified sound intensity. For example, the noise of a jet plane is 10,000,000,000,000 (or 10 13) times higher than our standard, that is, this standard must be multiplied 13 times by 10. This method of expression allows us to significantly reduce the values ​​​​of the numbers expressing the gigantic range of sound intensities; if we denote a single increase of 10 times as 1 bel, we get a “unit” to express ratios. Thus, the noise level of a jet aircraft corresponds to 13 bels. Bel turns out to be too large; It is more convenient to use smaller units, tenths of a bel, which are called decibels. Thus, the noise intensity of a jet engine is 130 decibels (130 dB), but to avoid confusion with any other sound intensity standard, it should be noted that 130 dB is defined relative to a reference level of 10 -12 W/m 2.

If the ratio of the intensity of a given sound to a reference intensity is expressed by some less round number, for example 8300, the conversion to decibels will not be so simple. Obviously, the number of multiplications by 10 will be greater than 3 and less than 4, but lengthy calculations are required to accurately determine this number. How to get around this difficulty? It turns out to be quite simple, since all ratios expressed in units of “tenfold increases” have long been calculated - these are logarithms.

Any number can be represented as 10 to some degree: 100 is 10 2 and therefore 2 is the logarithm of 100 to the base 10; 3 is the logarithm of 1000 to base 10 and, less obviously, 3.9191 is the logarithm of 8300. There is no need to keep saying “base 10” because 10 is the most common logarithm base, and unless otherwise specified, that is what is meant base. In formulas, this value is written as log10 or log.

Using the definition of decibel, we can now write the sound intensity level as:

For example, with a sound intensity of 0.26 (2.6 × 10 -1) W/m 2, the intensity level in dB relative to the standard 10 -12 W/m 2 is equal to

But the logarithm of 2.6 is 0.415; hence the final answer looks like this:

10 × 11.415 = 114 dB(accurate to 1 dB)

It should be remembered that decibels are not units of measurement in the same sense as, for example, volts or ohms, and that accordingly they must be treated differently. If two 6 V (volt) batteries are connected in series, then the potential difference at the ends of the circuit will be 12 V. What happens if you add another noise of 80 dB to a noise of 80 dB? Noise with a total intensity of 160 dB? No, because when a number doubles, its logarithm increases by 0.3 (accurate to two decimal places). Then, when the sound intensity doubles, the intensity level increases by 0.3 bels, that is, by 3 dB. This is true for any intensity level: doubling the sound intensity results in a 3 dB increase in the intensity level. In table Figure 1 shows how the intensity level, expressed in decibels, increases when sounds of different intensities are added together.

Table No. 1

Now, having solved the mystery of the decibel, let's give a few examples.

Noise level in decibels

In table 2 provides a list of typical noises and their intensity levels in decibels.

Table No. 2

How can you determine the intensity of a given sound? This is quite a difficult task; It is much easier to measure pressure fluctuations in sound waves. In table 3 shows the sound pressure values ​​for sounds of various intensities. From this table it can be seen that the range of sound pressures is not as wide as the range of intensities: pressure increases twice as slowly as intensity. When sound pressure doubles, the energy of the sound wave should increase fourfold - then the speed of the particles of the medium will correspondingly increase. Therefore, if we measure the sound pressure as well as the intensity on a logarithmic scale and, in addition, introduce a factor of 2, we obtain the same values ​​for the intensity level. For example, the sound pressure of the weakest audible sound is approximately 0.00002 N (newton)/m 2, and in the cab of a diesel truck it is 2 N/m 2, therefore, the noise intensity level in the cab is

Table No. 3

When expressing the sound pressure level in decibels, it should be remembered that when the pressure doubles, 6 dB is added. If the noise in the cabin of a diesel truck reaches 106 dB, then the sound pressure will double and amount to 4 N/m2, and the intensity will quadruple and reach 0.04 W/m2.

We talked a lot about the measure of sound intensity, but did not touch at all on practical methods for measuring this quantity. Measurable characteristics of a sound wave include intensity, pressure, velocity, and particle displacement. All these characteristics are directly related to each other, and if at least one of them can be measured, the rest can be calculated.

It is not difficult to see or feel the vibration of light objects that are in the path of a sound wave. The operating principle of the oscilloscope, the oldest type of sound level meter, is based on this phenomenon. An oscilloscope consists of a diaphragm with a thin thread attached to the center, a mechanical system to amplify the vibrations, and a stylus that records the displacements of the diaphragm on a paper tape. Such notations are reminiscent of the “wavy lines” we talked about in the previous chapter.

This device was extremely insensitive and was only suitable for confirming the acoustic theories of scientists of that time. The inertia of mechanical parts extremely limited the frequency response and accuracy of the device. Replacing the mechanical amplifier with an optical system and using the photographic method of signal recording made it possible to significantly reduce the inertia of the device. In the device improved in this way, the diaphragm thread was wound on a rotating drum, mounted on an axis, to which a mirror was attached, rotating with the drum. A ray of light fell on the mirror; when the mirror was turned in one direction or the other, which occurred as a result of vibrations of the membrane, the beam was deflected, and these deviations could be recorded on photosensitive paper. It was only with the development of electronics that more or less accurate measuring instruments were developed, and to design a modern portable sound level meter we had to wait for the invention of transistors.

Essentially, a modern sound level meter is an electronic analogue of an old mechanical device. The first step in the measurement process is to convert sound pressure into changes in electrical voltage; the microphone produces this conversion. Currently, such devices use microphones of various types: condenser, moving coil, crystal, ribbon, heated wire, Rochelle - this is only a small part of all types of microphones. In our book we will not consider the principles of their operation.

All microphones perform the same basic function, and most have a membrane of one kind or another that is driven by changes in pressure in the sound wave. Displacements of the membrane cause corresponding voltage changes at the microphone terminals. The next step in measurement is amplification and then rectification of the alternating current and the final operation is applying a signal to a voltmeter calibrated in decibels. In most of these devices, the voltmeter measures not the maximum, but the “rms values” of the signal, that is, the result of a certain type of averaging, which is used more often than the maximum values.

A conventional voltmeter cannot cover a huge range of sound pressures, and therefore in the part of the device where the signal is amplified, there are several circuits that differ in amplification by 10 dB, which can be switched on in series one after the other. However, an improved model of the old oscilloscope is still widely used. In a cathode ray oscilloscope, the problem of inertia inherent in a mechanical oscilloscope is completely eliminated, since the mass of the electron beam is negligible, and it is easily deflected by the electromagnetic field and draws a curve of voltage fluctuations supplied to the device on the screen.

The resulting oscillographic recording is used for mathematical analysis of the sound wave shape. Oscilloscopes are also extremely useful for measuring impulse noise. As we have already said, a conventional sound level meter continuously determines the RMS values ​​of the signal. But, for example, a sound clap or a gun shot does not generate continuous noise, but creates a single, very powerful, sometimes dangerous for hearing, pressure pulse, which is accompanied by gradually damping pressure fluctuations (Fig. 13). The initial pressure surge can damage hearing or break window glass, but since it is single and short-lived, the root mean square value will not be characteristic of it and can only lead to misunderstanding. Although there are special sound level meters for measuring pulsed sounds, most of them will not be able to register the full root-mean-square value of the pulse simply because they do not have time to operate. This is where the oscilloscope comes into its own, instantly plotting an accurate pressure rise curve so that the maximum pressure in a pulse can be measured directly on the screen.

Rice. 13. Typical impulse noise

Perhaps one of the most significant issues in acoustics is the dependence of the behavior of sound on its frequency. The lower frequency limit of human perception of sound is about 30 Hz, and the upper limit is no higher than 18 kHz; therefore, the sound level meter would have to register sounds in the same frequency range. But here a serious difficulty arises. As we will see in the next chapter, the sensitivity of the human ear for different frequencies is far from equal; so, for example, for sounds with a frequency of 30 Hz and 1 kHz to sound equally loud, the sound pressure level of the first of them must be 40 dB higher than the second. And therefore, the sound level meter readings by themselves are not worth much.

Electronics specialists have taken up this problem, and modern sound level meters are equipped with correction circuits consisting of separate chains, by connecting which you can reduce the sensitivity of the sound level meter to low-frequency and very high-frequency sounds and thereby bring the frequency characteristics of the device closer to the properties of the human ear. Typically, the sound level meter contains three correction circuits, designated A, B and C; correction A is most useful; correction B is used only occasionally; correction C has little effect on sensitivity in the range 31.5 Hz - 8 kHz. Some types of sound level meters also use a D correction, which allows the device to be read directly in PN dB units used to measure aircraft noise. Accurate calculation of PN dB is quite complex, but for high noise levels the level in PN dB units is equal to the dB level measured by a D-corrected sound level meter plus 7 dB; In most cases, jet aircraft noise expressed in PN dB is approximately equal to the dB level measured by an A-weighted sound level meter plus 13 dB.

Nowadays, almost everywhere, the noise level is taken to be equal to the level measured in dB using an A-weighted sound level meter, and is expressed in units of dBA. Although the human ear perceives sound incomparably more refined than a sound level meter, and therefore sound levels expressed in dBA by no means correspond exactly to physiological response, the simplicity of this unit makes it extremely convenient for practical use.

The major disadvantage of measuring loudness in dBA is that it underestimates our response to low-frequency sounds and completely ignores the ear's increased sensitivity to the loudness of pure tones.

One of the advantages of the dBA scale is, in particular, the fact that here, as we will see in the next chapter, doubling the volume roughly corresponds to an increase in the noise level by 10 dBA. However, even this scale gives no more than a rough indication of the role of the frequency composition of noise, and since this characteristic of noise is often extremely important, the results of measurements carried out using a sound level meter must be supplemented with data obtained using other instruments.

Frequencies, like intensities, are measured on a logarithmic scale, and the doubling of the number of oscillations per second is taken as the basis. Since, however, the range of frequencies is less wide than the range of intensities, the number of tenfold increases is not calculated, decimal logarithms are not used, and sound frequencies are always expressed by the number of oscillations, or cycles per second. The unit of frequency is one oscillation per second, or 1 hertz (Hz). Determining the sound intensity for each frequency would require an infinite number of measurements. Therefore, as in musical practice, the entire range is divided into octaves. The highest frequency in each octave is twice the lowest. The first, simplest stage of frequency analysis of sound is measuring the sound pressure level within each of 8 or 11 octaves, depending on the frequency range of interest to us; When measuring, the signal from the output of the sound level meter is fed to a set of octave filters, or to an octave bandpass analyzer. The word “band” indicates a particular portion of the frequency spectrum. The analyzer contains 8 or 11 electronic filters. These devices pass only those frequency components of the signal that lie within their band. By turning on the filters one at a time, you can sequentially measure the sound pressure level in each band directly using a sound level meter. But in many cases, even octave analyzers do not provide sufficient information about the signal, and then they resort to more detailed analysis, using half or one-third octave filters. To obtain even more detailed analysis, narrow-band analyzers are used, which “cut” the noise into bands of constant relative width, for example 6% of the average frequency of the band, or into bands with a width of a certain number of hertz, for example 10 or 6 Hz. If the noise spectrum contains pure tones, which often happens, their frequency and amplitude can be accurately determined using a discrete frequency analyzer.

Typically, sound analyzing equipment is very bulky, and therefore its use is limited to laboratories. Quite often, the sound to be examined is recorded via a microphone and amplification circuits of the sound level meter on a high-quality portable tape recorder, using control signals for calibration; the recording is then played back in the laboratory, sending a signal to an analyzer, which automatically draws a frequency spectrum on a paper tape. In Fig. Figure 14 shows spectra of typical noise obtained using octave, one-third octave and narrowband (6 Hz band) analyzers.

Rice. 14. Sound analysis using octave, one-third octave and 6 Hz filters.

However, to measure noise, it is not enough to know the volume level and frequency of the sound. If we talk about environmental noise, it consists of many individual noises of various origins: these are the noise of street traffic, aircraft, industrial noise, as well as noise arising from other types of human activity. If you try to measure the noise level on the street with a conventional sound level meter, you will find that this is an extremely difficult task: the sound level meter needle will continuously fluctuate over a very wide range. What should be taken as the noise level? Maximum countdown? No, this figure is too high and insignificant. Average level? This would be possible, but it is extremely difficult to estimate the average value for any specific period of time, and in order to keep the needle within the scale, you will have to continuously change the gain levels of the sound level meter.

Table No. 4

There are two generally accepted methods for taking into account noise level fluctuations that allow this level to be expressed numerically. The first method uses a so-called statistical distribution analyzer. This device records the relative proportion of time during which the measured noise level is within each of the scale steps, located, for example, every 5 dB. The results of these measurements indicate the fraction of the total time during which each sound level was exceeded. By plotting the numbers presented in table. 4, by connecting the points with a smooth line and establishing the levels that were exceeded 1, 10, 50, 90 and 99% of the time, we can give a satisfactory description of the “noise climate”. These levels are designated as follows: L1, L10, L50, L90 and L99. L1 gives an idea of ​​the maximum value of the noise level, L10 is a characteristic high level, while L90 seems to show the background noise, that is, the level to which the noise decreases when a temporary lull occurs. Of great interest is the difference between the values ​​of L10 and L90; it indicates the extent to which the noise level varies in any given place, and the greater the fluctuations in noise, the greater its irritating effect. However, the L10 level itself is a good indicator of the disturbing effect of traffic noise; this indicator is widely used in measuring and forecasting traffic noise, and taking it into account, the amount of state compensation for victims of noise from new highways and roads is determined (see Chapter 11). So, L10 is the sound level, expressed in dBA, which is exceeded for exactly ten percent of the total measurement time.

Typically, traffic noise fluctuates in a very specific way, so the L10 level serves as an independent, fairly satisfactory indicator of noise, although it only partially represents the statistical picture of noise. If the noise changes randomly, as, for example, occurs when railroad, industrial, and sometimes airplane noise overlaps, the distribution of noise levels varies greatly from point to point. In such cases, it is also advisable to express all statistics in one number. Attempts have been made to invent a formula that includes the entire noise picture, including the scope of noise fluctuations. Such indicators include the “transport noise index” and “noise pollution level,” but the most common indicator is a special kind of average value, denoted Leq. It characterizes the average value of sound energy (as opposed to the arithmetic averaging of levels expressed in dB); sometimes Leq is called the equivalent level of continuous noise, because numerically this value corresponds to the level of such strictly stable noise at which, over the entire measurement period, the microphone would receive the same total amount of energy that enters it with all the irregularities, bursts and emissions of the measured fluctuating noise. In the simplest case, Leq will be, for example, 90 dBA if the noise level was 90 dBA all the time, or if the noise was 93 dBA for half the measurement time and completely absent the rest of the time. Indeed, since doubling the intensity or energy of noise leads to an increase in its level by 3 dB, then in order to keep the total amount of energy constant when doubling the noise intensity, the duration of its action should be halved. Similarly, we obtain the same value of Leq = 90 dBA at a noise level of 100 dBA, if it operates for one tenth of the same period of time. Measuring electricity consumption using an electric meter is done in a similar way. In practice, periods of constant noise levels and periods of complete absence do not occur often, and therefore it is quite difficult to calculate Leq. This is where distribution tables like table come to the rescue. 4, or specially designed automatic meters. The Leq index has two disadvantages: when averaging, short bursts of high-level noise make a larger contribution than periods of low-level noise; In addition, an increase in the number of maxima has little effect on the value of Leq. For example, if averaging the noise from 100 trains per day, the equivalent level is Leq = 65 dBA, then when the number of trains doubles, Leq increases by only 3 dBA. In order for the value of Leq to increase in the same way as doubling the volume (that is, as if increasing the level by 10 dBA) of the noise created by each of the trains, their number would have to be increased 10 times. And yet, despite some inferiority, the Leq scale represents the best universal measure of noise currently available. In England it will gradually become as widespread as it is on the continent. It is now being used in England to measure noise exposure to industrial employees.

Another measure is also used, which is essentially much more similar to Leq than it might seem at first glance: this is the standard noise index, unfortunately all too familiar to those who live near large airports. The scale of normalized noise indices is used to characterize the average maximum noise levels of aircraft, expressed in PN dB (the so-called “perceived sound level”, see Acoustic Dictionary), and since it starts from a level of 80 PN dB (about 67 dBA), the value 80 is subtracted from the average maximum level. Theoretically, if only one aircraft produces noise during the measurement, the value of this index will be exactly equal to the average maximum level in PN dB minus 80. With each doubling of the number of aircraft, 4.5 units should be added to this number, and not 3, as for the Leq scale. Although the formula for this index looks somewhat overwhelming, above we were able to actually fully characterize it. If individual aircraft noise peak levels differ by only a few dB, the average value can be calculated arithmetically. Otherwise, noise level values ​​expressed in dB will have to be converted back to intensity values, which requires a table of logarithms and a clear head!

There are many other measures, scales and indices for measuring noise, including phons, sones, nois, various derivatives of PN dB and a number of other criteria, not counting all the international versions of the noise standard indices scale. There is no need to describe other units and indicators. It should be noted that in the USA, the Leq indicator is used to measure noise in the workplace, but when the time of exposure to noise doubles, they add not 3 dB to its value, as in Europe, but 5 dB. Otherwise, dBA, L10 and Leq are applied equally throughout the world.

The state of the Russian Federation provides an hour-long period during which it is prohibited to make noise, listen to music and carry out repair work in residential buildings. Plus, the peace and quiet of citizens is protected during the day and at night. There is also the concept of permissible noise level. The noise level in an apartment (its maximum permissible standards in decibels) is especially relevant for residents of apartment buildings living in large cities. Here, unacceptable noisy behavior can come not only from neighbors. When loud sounds cause concern, even at permitted times, if the maximum permissible noise level is exceeded, every citizen of the Russian Federation has the right to conduct an examination and bring the offender to justice. For example, neighbors may be listening to music through amplifiers too loudly, or there may be construction going on under their windows.

The noise level of any sound is measured in decibels. The legislation of the Russian Federation establishes a standard of 55 decibels during the day and 45 decibels at night. These maximum permissible standards should in no case be exceeded, since exposure to increased noise has a negative impact on human health. In particular, the nervous system suffers and headaches occur. Therefore, it is important to know how to act in such cases.

Rules of law

The maximum permissible noise level in residential premises during the day and night is established not by the codes of the Russian Federation, but by sanitary authorities. No matter how many decibels the outgoing sound makes, whatever the source, a mark of seventy and above is already considered harmful to the physical and psychological state of citizens. And if you can deal with violators at night by calling the local police officer, when, for example, neighbors are listening to music loudly. It will be more problematic to deal with the situation during the day, without special expertise. This can be done by calling employees of the sanitary-epidemiological station or a commission from Rospotrebnadzor. In any case, the complaint will be officially recorded, and after the necessary measurements have been taken, a report will be drawn up.

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In addition to the reproduced noise in residential buildings from neighbors, there is also such a thing as compliance by the developer with standards when constructing residential buildings and premises. According to the laws of the Russian Federation, the sound insulation of an apartment building should not exceed fifty decibels. This refers to noise that is transmitted through the air. For example, conversations between neighbors, the usual operation of a TV behind the wall, etc. If the established acceptable standards are violated, the developer will face a rather large fine after filing a complaint from residents and conducting all examinations.

Why is increased sound dangerous?

Whatever the reason, and no matter how long the extraneous sounds last, exceeding the permissible noise in decibels, both during the day and at night, this interferes with rest, work, and study. It has a very negative effect on the human body. Such an impact can have unpleasant consequences:

In addition, in the Russian Federation it was found that the influence of sounds above seventy decibels increases the risk of accidents and leads to hearing loss. This impact has a particularly negative impact on young children, women, citizens of retirement age, and the disabled.

Comparative indicators of permissible noise level in decibels:

You can also note that being briefly exposed to noise up to sixty decibels is not dangerous, but systematic noise above sixty will lead to disturbances and disorders of the nervous system.

How is it measured?

Measuring the permissible noise level in residential buildings on their own is problematic for many citizens of the Russian Federation, since special devices for such measurements - sound level meters - are very expensive, and cannot be called an essential item. In addition, it makes no sense to buy such a device simply because independently recorded data will not be accepted by any institution. Specialists must draw up the acts.

The need to check whether disturbing noise exceeds permissible standards and to complain about violators does not arise very rarely. For example, it could be not only noisy neighbors, but also a club, karaoke bar, or other entertainment venue located next to the house or in the house itself. In this case, you need to contact specialists from government or private structures of the Russian Federation, who will measure the sound in a given apartment of a residential building. In this case, such a measurement will be carried out more than once, ideally twice during the day and twice at night. The closed and open window will also be taken into account.

You can contact specialists to measure the level of permissible noise standards during the day and at night if ordinary sounds from the street penetrate into the apartment of a residential building and cause discomfort. This is done in order to check whether sound insulation standards are met during the construction of a residential building. If this fact is proven, repair work to improve sound insulation will have to be carried out by developers.

Whoever conducts the examination in the Russian Federation in residential premises, then a legal document is drawn up with all the recorded information. This document can be used when filing a lawsuit.

Why is expertise needed?

Exceeding the permissible noise standard for residential buildings in the Russian Federation is one of the main factors of environmental pollution. This means that this indicator must be regularly monitored in order to avoid deterioration in health. The Sanitary and Epidemiological Station has developed a number of regulatory documents that determine the degree of danger of noise, both in residential premises and on the street, in industries, medical and educational institutions. In the daytime and at night these are different indicators; by the way, during the day they are higher.

Table of permissible noise levels for air conditioning and ventilation systems

Control in different areas is carried out by different services. The State Inspectorate deals with noise at work. At the workplaces of other organizations, the supervisory authority is the Labor Inspectorate, but the sanitary and epidemiological service itself checks the permissible standards in residential premises.

Please note

Increased noise in residential buildings, especially if it is regular, at night or during the day, cannot be ignored. Because sooner or later it will affect human health. Whether it is the sound of music from neighbors, discos in a neighboring building, repair work using electric tools, it does not matter.

Before hiring a noise level measurement specialist, it is worth checking whether they are licensed to do this activity. Before the start of cooperation, albeit short-term, an agreement must be drawn up between the experts and the customer. After taking measurements, it is important to make sure that the documents contain the correct information. And only after receiving a document about the examination performed, you can contact the sanitary-epidemiological service or Rospotrebnadzor directly. As a last resort, if this does not produce any results, you need to go to court.

When neighbors constantly listen to loud music, especially at prohibited times, it is advisable to call the local police officer. Record violations, write statements and draw up an act of violation. If you go to court, these documents will be needed.

Often citizens, especially city residents, complain about excessive noise in apartments and on the street. It is especially annoying (the noise) on weekends and at night. And during the day there is little joy from it, especially if there is a small child in the apartment.

Both experts and the Internet are unanimous in their advice - you need to call the local police officer. But before contacting a law enforcement representative, it is necessary to at least roughly understand the noise levels at which such treatment is justified, and which is only an irritating factor, but is not prohibited.

Permissible noise levels in residential premises

It is regulated by legislative acts, according to which the time of day is divided into periods and for each period the permissible noise level is different.

• 22.00 – 08.00 period of silence, during which the specified level should not exceed 35-40 decibels (this is where this indicator is considered).
• From eight in the morning to ten in the evening, according to the law, it refers to daylight hours and the noise can be a little louder - 40-50 dB.

Many people are interested in why there is such a difference in dB. The thing is that the federal authorities gave only approximate values, and each region sets them independently. For example, in some regions, in particular in the capital, there are additional periods of silence during the day. Usually this is from 13.00 to 15.00. Failure to remain silent during this period is a violation.

It is worth saying that the standards mean the level that cannot cause any harm to human hearing. But many do not understand what these indicators mean. Therefore, we provide a comparison table with noise levels and what to compare with.

• 0-5 dB – nothing or almost nothing is heard.
• 10 – this level can be compared to the slight rustling of leaves on a tree.
• 15 – rustling of leaves.
• 20 – barely audible human whisper (at an approximate distance of one meter).
• 25 – level when a person speaks in a whisper at a distance of a couple of meters.
• 30 decibels compared to what? - a loud whisper, the ticking of the clock on the wall. According to SNiP standards, this level is the maximum permissible at night in residential premises.
• 35 – approximately at this level the conversation is conducted, albeit in muted tones.
• 40 decibels is normal speech. SNiP defines this level as acceptable for daytime.
• 45 is also a standard conversation.
• 50 – the sound a typewriter makes (the older generation will understand).
• 55 – what can this level be compared to? Yes, the same as the top line. By the way, according to European standards, this level is the maximum permissible for class A offices.
• 60 is the level determined by law for ordinary offices.
• 65-70 – loud conversations at a distance of one meter.
• 75 – human cry, laughter.
• 80 is a working motorcycle with a muffler, also this is the level of a working vacuum cleaner with an engine power of 2 kW or more.
• 90 - the sound made by a freight car when moving on a piece of iron and can be heard at a distance of seven meters.
• 95 is the sound of a subway car when moving.
• 100 – at this level a brass band plays and a chainsaw works. The sound of the same power is made by thunder. According to European standards, this is the maximum permissible level for the player’s headphones.
• 105 - this level was allowed in passenger airliners until the 80s. last century.
• 110 – noise made by a flying helicopter.
• 120-125 – the sound of a chipper operating at a distance of one meter.
• 130 – this is how many decibels a starting plane produces.
• 135-145 - a jet plane or rocket takes off with such noise.
• 150-160 – a supersonic aircraft crosses the sound barrier.

All of the above are conditionally divided according to the level of impact on human hearing:

• 0-10 – nothing or almost nothing is heard.
• 15-20 – barely audible.
• 25-30 – quiet.
• 35-45 is already quite noisy.
• 50-55 – clearly audible.
• 60-75 – noisy.
• 85-95 – very noisy.
• 100-115 – extremely noisy.
• 120-125 is an almost unbearable noise level for human hearing. Workers working with a jackhammer must wear special headphones, otherwise hearing loss is guaranteed.
• 130 is the so-called pain threshold; a sound higher than this is already fatal for human hearing.
• 135-155 – without protective equipment (headphones, helmets), a person experiences concussion and brain injury.
• 160-200 – guaranteed rupture of the eardrums and, attention, lungs.

Above 200 decibels can not even be considered, as this is a lethal sound level. It is at this level that the so-called noise weapon operates.

What else

But even lower values ​​can lead to irreversible injuries. For example, long-term exposure to a sound of 70-90 decibels on hearing has a detrimental effect on a person, in particular on the central nervous system. For comparison, this is usually a loud TV playing, the level of music in the car for some “lovers”, the sound in the headphones of the player. If you still want to listen to loud music, be prepared for the fact that you will have to deal with your nerves for a long time.

And if the noise exceeds 100 decibels, then hearing loss is almost guaranteed. And as practice shows, music at this level produces more negativity than pleasure.

In Europe, it is prohibited to place a lot of office equipment in one room, especially if the room is not decorated with sound-absorbing materials. Indeed, in a small room, two computers, a fax machine and a printer can raise the noise level to 70 dB.

In general, in the workplace the maximum noise level can be no more than 110 dB. If somewhere it exceeds 135, then any human presence, even short-term, is prohibited in this area.

If the noise level in the workplace exceeds 65-70 dB, it is recommended to wear special soft earplugs. If they are made well, they should reduce external noise by 30 dB.

Isolating headphones, sold in hardware stores, not only provide maximum protection from almost any noise, but will also protect the temporal lobe of the head.

And in conclusion, let’s say one interesting piece of news that might seem funny to some. Statistics have shown that a city dweller living in constant noise, once in a zone of complete silence, where the noise level does not exceed 20 dB, begins to experience discomfort. What can I say, he begins to feel depressed. This is such a paradox.