Prevention of harmful effects of noise on the human body begins with its rationing. The rationing of noise is to establish safe levels of sound, the excess of which is the threat of life and health of the population, as it creates the risk of developing diseases associated with unfavorable action.

Normated in the following indicators:

• sound level (for constant noise);
• equivalent sound level (this indicator equates the sound level of non-permanent noise for a certain period of time to a certain level of sound of constant broadband noise);
• maximum sound level (for non-permanent noise);
• levels sound pressure In octave stripes with medium-meter frequencies 31.5 Hz, 63 Hz, 125 Hz, 250 Hz, 500 Hz, 1000 Hz, 2000 Hz, 4000 Hz, 8000 Hz.

The principles of rationing of noise in residential and public rooms And in the workplace differ from each other.

Normation of noise in residential and public buildings and on the territory adjacent to them

For residential premises and premises in public buildings and institutions, permissible noise levels are installed.

The permissible level of noise is the level that does not cause significant concern in humans and significant changes in indicators. functional state Systems and analyzers sensitive to noise.

In other words, such noise is not only not noticeable for a person, but also will not cause absolutely no physiological effects from the body. To such noise human organism It does not have to adapt, and it means that it is not a stress factor.

Let me remind you that the criterion of "visibility" of noise, i.e. His subjective perception, in itself can not determine any noise norms, since a person gets used to subjective perception of even enough high noise levels, but does not get addictive to noise in the physiological sense. The fatigue and physiological effects caused by noise over time accumulate and can pour out in various functional disorders and diseases, which is why the ability of noise at the well-known levels to cause the appearance of such effects determines the noise norms along with its subjective perception.

If the permissible level of noise is not exceeded, it does not bother people in such an environment, creates a comfortable atmosphere to perform everyday affairs, does not cause fatigue and contributes to active or relaxing rest.

When normalizing noise taken into account and various states man like physiological and caused various diseases, for example, the noise that is invisible for a waking person, especially if he is having fun or engaged in an active holiday, will interfere with a person who is trying to fall asleep, which means it will prevent the normal flow of sleep and rest the body, which is fraught with his health. Therefore, for premises in which people can be around the clock are installed various standards for daytime days (from 7 to 23 hours) and for night time (from 23 hours to 7h).

Similarly, noise that does not interfere healthy personmay be the cause of discomfort for a person of the patient. Therefore, for residential premises, and for premises equated to them, noise norms are slightly higher than for hospitals and sanatorium chambers.

In training rooms, permissible noise levels are commensurate with norms for residential premises, because in order to focus on the educational process, any distracting factors completely cannot do anything.

For public institutions in which people are having fun, make purchases, receive any noise services higher than for residential premises, educational and medical institutions.

Permissible noise levels and for public areas are established.

Where noise norms are installed for residential and public spaces

Permissible noise levels are established in special regulatory documents that regulate the safety criteria and harmlessness for human health of various habitat factors and demands that provide favorable conditions for people's vital activity. Such documents are: sanitary rules (SP), sanitary and epidemiological rules and regulations (SanPiN), sanitary standards (CH).

All listed types of documents are mandatory for the fulfillment of their requirements by citizens, individual entrepreneurs, legal entities regardless of their affiliation and type of property.

For non-performance of the mandatory requirements of the above regulatory documents, civil, administrative and criminal liability is provided.

The main document establishing permissible noise levels is CH 2.2.4 / 2.1.8.562-96 "Noise in the workplace, in the premises of residential, public buildings and in the residential building."

In addition to him, noise norms are regulated in specialized joint ventures and SanPiN, for example, SanPine 2.1.2.2645-10 "Sanitary and epidemiological requirements for living conditions in residential buildings and premises", SP 2.1.2.2844-11 "Sanitary and epidemiological requirements for device, equipment and equipment and The content of the hostels for employees of organizations and students educational institutions" etc.

The concept of noise

Noise - This is an indiscriminate fluctuations in various physical nature, characterized by the complexity of the time and spectral structure. From a physiological point of view, noise is every unfavorable perceived sound.

Sound - these are elastic waves that extend in the medium and create mechanical oscillations in it; In a narrow sense, the subjective perception of these oscillations by special human senses.

The impact of the factor on the human body

The prolonged effect of noise can lead to a deterioration of hearing, and in some cases - to deafness. The noise effect on the workplace is adversely affected by working and leads to:

decline in attention;

an increase in energy consumption with the same physical exertion;

• slowdown the speed of mental reactions, etc.

The concept of sound, as a rule, is associated with the auditory sensations of a person with normal hearing. Hearing sensations They are caused by oscillations of an elastic medium, which are mechanical oscillations propagating in a gaseous, liquid or solid medium and affecting human hearing organs. At the same time, medium fluctuations are perceived as sound only in a certain frequency domain (20 Hz - 20 kHz) and at sound pressures exceeding the human hearing threshold.

As a result, labor productivity and the quality of work performed is reduced.

Figure 1 shows the structure of the hearing organ.

Figure 1 - the structure of the organ of hearing

In the snail there is a primary analysis of sound. Each simple sound has its own plot on the basilar membrane. Low sounds cause oscillations of the site of the basilar membrane at the top of the snail, and the high - at the base of it.

The wave moves away from the tears of the tip of the snail. When the amplitude reaches its maximum, the wave quickly fades. In this area there are vortine-shaped currents of perilimphs, and maximum deflection of the basilar membrane occurs. Low-frequency sounds will pass throughout the snail and cause maximum deflection at the top. High-frequency sounds will scatter the basilar membrane only at the base of the snail. The nervous excitement in the auditory receptor auditory nerve It is transmitted to the hearing zone of the cerebral cortex, where the sound image is formed. Figure 2 shows the mechanism for the formation of audible sounds.

Figure 2 - The mechanism of formation of audible sounds

Areas of perception of sound intensity levels

I area - includes a level range from a hearing threshold of up to 40 dB and covers a limited number of signals, as a result of which a person does not have a daily training for the perception of such sounds; In this case, the ability to differentiate sounds is limited.

The II region - includes levels from 40 to 80 - 90 dB and covers the bulk of the useful signals, the levels of speech intensity from the whisper are stacked in this area until the loudest radio broadcasts, musical sounds, etc. It has the ability to the fine differentiation and the analysis of sound quality (and frequency and intensity). The person is most adapted to the perception of sounds of this area.

• III area - covers levels from 80 - 90 dB to the threshold of an unpleasant sensation - 120-130 dB. In this area, the function of the auditory analyzer has significant differences depending on the frequency, intensity and time of the impact of sound.

Classification of factor

The classification of the "Noise" factor is given in Table 1.

Table 1

Normated indicators of factors

Normated indicators for constant and non-permanent noise are shown in Table 2.

table 2

Standards

Maximum allowable noise levels on workplaces are installed, taking into account gravity and tension labor activity. To determine the noise of noise corresponding to a specific workplace, it is necessary to conduct a quantitative assessment of the gravity and tensions of labor performed by the employee. Maximum permissible levels of sound and equivalent levels of sound at workplaces for labor activity of various categories of gravity and tension in the dBA are presented in Table 3.

Table 3. Maximum allowable sound levels and equivalent sound levels on workplaces for labor activity of different categories of gravity and tension in dba

The maximum permissible levels of sound pressure, sound levels and equivalent sound levels for the main most typical types of work and jobs are presented in Table 4.

Table 4. Maximum permissible sound pressure levels, sound levels and equivalent sound levels for the main most typical types of labor activity and jobs

Classes of labor conditions Depending on the noise levels are presented in Table 5

Table 5. Classes of working conditions depending on the noise levels in the workplace

Methodology for measuring

When measuring, in some reference time intervals, they are chosen so that they cover all the characteristic and repeating day-to-day noise situations [it is important to identify all significant changes in noise in the workplace, for example, 5 dB (dBA) and more]. In this case, the measurement results obtained in various shifts will not be contradictory.

Duration of measurements within each reference time interval

for constant noise at least 15 s;

for non-permanent, including intermittent, noise, it should be equal to the duration of at least one repeated working cycle or multiple to several working cycles. The duration of measurements may also be equal to the duration of a certain characteristic type of work or its part. The duration of measurements is considered sufficient if, with further increasing it, the equivalent sound level does not change by more than 0.5 dBA;

• for non-permanent noise, the causes of whose oscillations cannot be explicitly related to the nature of the work performed, 30 minutes (three measurement cycles of 10 minutes) or less, if the measurement results at a lower duration do not differ by more than 0.5 dB (dBA);

for impulse noise - no less time of passing 10 pulses (15 - 30 seconds recommended)

Noise measurements To monitor the correspondence of actual noise levels in the workplace, permissible levels on current standards should be carried out when operating at least 2/3 commonly used units of installed equipment in this room in the most common (characteristic) mode of its operation or otherwise, when typical Noise impact on the side of noise sources that are not at the workplace (in the working area). If it is known that the equipment far from the workplace creates a background noise on 15-20 dB on it lower than noise when equipped with equipment installed at this workplace, it should not be included.

Measurements should not be carried out when conversations of working, as well as when applying various sound signals (warning, information, telephone calls, etc.) and when working loud-speaking communication.

Measurements can be carried out in the presence or absence (last preferable) operator (working) in the workplace or in the working area. Measurements are carried out at fixed points or using a microphone fixed on the operator and moving with it, which provides a higher accuracy of determining the noise level and is preferable.

Measurements at a fixed point are carried out if the position of the operator's head is known exactly. In the absence of an operator, the microphone is installed at a specified measurement point located at the level of its head. If the position of the operator's head is not exactly known and measurements are carried out in the absence of an operator, the microphone is installed for a sedent workplace at a height (0.91 ± 0.05) m above the center of the seating surface during its average adjustment position for the operator's growth, and for standing working Places - at a height (1.550 ± 0.075) m above the support of the vertical passing through the center of the head of a straight person.

If the presence of the operator is necessary, then the microphone is set at a distance of approximately 0.1 m from the ear perceiving greater (equivalent) sound level, and orient in the direction of the operator's view, if possible, or in accordance with the manufacturer's instruction. If the microphone is fixed on the operator, it is installed on a helmet or shoulder using a frame, as well as on the collar at a distance of 0.1 - 0.3 m from the ear, but so as not to prevent the operation of the operator and do not create danger.

The microphone must be removed at least 0.5 m from the operator conductive.

Near the noise source, even minor changes in the position of the microphone can significantly affect the measurement results. If at the measurement point is well distinguishable, then there may be standing waves. The microphone is recommended to move several times in zone 0.1 - 0.5 m and as a measurement result, take the average value.

When the microphone is located close to the operator, a noticeable difference may be observed in the presence of an operator and without it (usually the measurement results in the presence of the operator above). This is especially manifested when measuring high-frequency tonal noise or noise of small sources close to them. To prevent coarse errors, it is recommended to compare the measurement results in the presence of an operator and without it and in case of their significant difference, calculate the average value.

Octave sound pressure levels, sound levels are measured by noiseomers of the 1st or 2nd accuracy class.

The equipment is calibrated before and after measuring noise in accordance with instructions for instructions.

Figure 3 shows the means of measuring the level of sound pressure.

Figure 3 - Means of measurement level of sound pressure

Actual sound pressure levels

Examples of actual soundproof levels are shown in Figure 4.

Figure 4 - actual sound pressure levels

Events to eliminate the harmful effects of noise

Events to protect against the noise of workplaces of industrial enterprises are primarily provided by the following construction and acoustic methods.

Rational from an acoustic point of view The decision of the objective plan of the object, the rational architectural and planning solution of buildings

The main principle of protection is the grouping of premises with an elevated level of noise and their separate location from other parts of the building. As for the equipment of these premises, the most favorable is considered to install it in the center of the room. In this case, there will be only one reflective surface - the floor. When installing equipment in the wall, it will also reflect sound waves, and the noise will be intensified. This principle acts to protect against structural noise, with the only difference that the equipment should not touch the walls of the room.

The use of enclosing structures of buildings with the required sound insulation

Fluent structures of buildings are walls, overlaps, partitions, and the like. They are divided into external and internal. External serve to protect against various climatic factors, and internal enclosing structures - for separation and redevelopment of the inner space of the building.

Elements of fences are recommended to be designed from materials with a dense structure that does not have through pores. Fencing made of through-porosity materials must have an outer layers of dense material, concrete or solution.

The inner walls and partitions of brick, ceramic and slag concrete blocks are recommended to be designed with the filling of the seams to the entire thickness (without PUS-Toshovka) and placed on both sides by a sauced solution.

Fencing structures need to be designed so that in the process of construction and operation in their joints there is no even minimal through slots and cracks. Arriving in the construction process of the gap and cracks after their clearing should be eliminated with constructive measures and sealing non-drying sealants and other materials for the entire depth.

Soundproofing of the building structures is carried out by covering them with sound-absorbing materials. The efficacy of sound insulation depends on the type of material used and from its thickness. Fibrous materials are most effective, which, due to their structure, are missing only a small percentage of noise. The thickness and material of the structures is determined on the basis of conducting acoustic calculations.

Application of sound-absorbing structures

The presence of reflections of sound waves from the surfaces of the closed space (room) and the objects that are in it usually increase the intensity of the sound compared to the levels created by the same sound source emitting to free (open) space. To eliminate the reflected part of the sound field, various sound-absorbing materials and structures based on them are used.

Sound-absorbing structures (suspended ceilings, wall cladding, snacks and piece absorbers) should be used to reduce noise levels at workplaces and in the areas of permanent stay of people in industrial and public buildings.

Sound-absorbing structures should be placed on the ceiling and on the upper parts of the walls. It is advisable to place sound-absorbing designs with individual sites or stripes. At frequencies below 250 Hz, the efficiency of sound-absorbing cladding increases when it is placed in the corners of the room.

Sound-absorbing facing area and the number of pieces of absorbers are determined by the calculation.

Pieces absorbers should be used if the facing is not enough to obtain the required reduction in noise, as well as instead of a sound-absorbing suspended ceiling, when its device is impossible or ineffectively (a large height of the production room, the presence of bridge cranes, the presence of light and aeration lamps). As mandatory measures to reduce noise and ensure optimal acoustic parameters of premises, sound-absorbing structures should be applied: in noisy shops manufacturing enterprises; in the machine halls of computing centers; In soundproofing cabins, boxes and shelters.

The acoustic properties of materials substantially depend on their structural parameters, which determine the scope of application of these materials. So, if noise reduction in the low frequency range is required, then it is advisable to use cladding made of ultra-or super-thin fibrous materials with a density of 15-20 kg / m3. To reduce broadband noise in the middle and high frequency range, materials with larger fibers with a density of 20 - 30 kg / m3 and more should be selected.

It should be noted that in the area of \u200b\u200bdirect sound, sound-absorbing structures practically do not reduce noise levels.

Application of soundproofing and remote control cabins

Soundproofing cabins should be used in industrial shops and in the territories where permissible levels are exceeded, to protect the noise of workers and service personnel. In soundproofing cabins, the consoles of control and management of "noisy" technological processes and equipment, workplaces of masters and heads of workshops should be positioned.

Depending on the required sound insulation of the cabin can be designed from conventional building materials (bricks, reinforced concrete, etc.) or have a prefabricated structure collected from pre-made structures made of steel, aluminum, plastic, plywood and other sheet materials on the national or weld frame .

Soundproofing cabins should be installed on rubber vibration insulators to prevent the transmission of vibrations on the enclosing structures and the cab frame. The internal cabin volume should be at least 15 m3 per person. The height of the cabin (inside) is at least 2.5 m. The cabin should be equipped with a system of ventilation or air conditioning with the necessary silencers of noise. The inner surface of the cabin should be 50 - 70% lined with sound-absorbing materials.

Cabin doors must have sealing gaskets in the focus and locking devices that provide gaskets. In the cabins of the 1st and 2nd classes there must be double doors with a tambour.

The use of soundproof housings on noisy units

The use of soundproof housings is one of the most effective solutions to the problem of insulation of units with an elevated noise level. It is advisable to apply a soundproofing casing in cases where the noise created by the unit (machine) at the calculation point exceeds the allowable value by 5 dB and more at least in one octave strip, and the noise of the remaining technological equipment in the same octave strip (at the same calculated point ) 2 dB and more permissible.

Sound-insulating covers, as a rule, are made of fibrous materials, and the framework serves thin perforated metal panels. If the magnitude of the air noise sound insulation does not exceed 10 dB on medium and high frequencies, the casing can be made of elastic materials (vinyl, rubber, etc.), if more - the casing should be made from leaf structures. Casing elements must be attached on the frame.

The casing should be covered with vibration-absorbing material (sheet or in the form of mastic), while the thickness of the coating should be 2-3 times the thickness of the wall. From the inside, the casing should be placed a layer of sound-absorbing material with a thickness of 40 - 50 mm. For its protection against mechanical impacts, dust and other contaminants, you should use a metal mesh with a fiberglass or a thin film with a thickness of 20-30 μm.

The casing should not have direct contact with the unit and pipelines. Technological and ventilation holes should be equipped with silencers and seals. Installation of soundproof housings is one of the main activities to reduce the noise of ventilation equipment in buildings and rooms. They are installed on the supply, some exhaust installations and air conditioners. Sound-insulating housings are two metal sheets with sound-absorbing material between them. The acoustic efficiency of such housings can be up to 10 - 15 dB at low and up to 30 - 40 dB - at high frequencies.

Application of acoustic screens

The acoustic screen is some barrier between the workplace and the source of noise having a high level of sound insulation. Screens should be used to reduce sound pressure levels at workplaces in the area of \u200b\u200bdirect sound and in the intermediate zone. Install screens should be closer to the noise source.

Screens should be made of solid sheet materials or individual shields with mandatory cladding sound-absorbing surface materials facing the source of noise.

Constructively, the screens can be flat and p-shaped (in this case, their efficiency increases). If the screen surrounds the noise source, then it turns into a slurry and its effectiveness is approaching the efficiency of an infinite screen with a height H. The weiglock is advisable to apply noise for the source (sources) of noise, the levels of sound power of which are 15 dB and more higher than that of other noise sources.

Screen elements can be located vertically and under a specific slope to the horizontal (vertical) plane. The angle of inclination depends on the mutual location of the source of noise and the workplace.

The main parameters of the screen (height, shape, the thickness of the sound-absorbing cladding), under which a given acoustic efficiency is provided at a fixed distance to the noise source are determined by the estimated path. Linear screens sizes should be at least three times the linear dimensions of the noise source.

Without the noise of fans and the use of noise silencers in ventilation systems, air conditioning and in aerogazodynamic installations

To reduce the fan noise: select the unit with the lowest specific levels of sound power; ensure the operation of the fan in the maximum efficiency mode; reduce network resistance and not apply a fan that creates overpressure; Provide a smooth air supply to the inlet fan nozzle.

To reduce noise from the fan along the path of its propagation through the air ducts, it follows: to provide for the central (directly at the fan) and the end (in the air duct before the air distribution devices) noise silencers; Limit air movement speed in the networks of the amount of noise generated by regulating and air distribution devices within the allowable values \u200b\u200bin the served rooms.

A tubular, lamellar, channels, cylindrical, screen and chamber, and lined with sound-absorbing materials of the air ducts and their turns can be used as silencers of noise of ventilation systems.

The design of the muffler should be selected depending on the size of the duct, the required reduction in noise levels, the permissible air velocity based on the calculation of the corresponding draft of the rules.

Vibration Isolation of technological equipment

Air noise, especially vibration, spreading with small attenuation on the carrier and enclosing structures of buildings, as well as on pipelines and walls of channels and mines in buildings, emitted as a structural (shock) noise in rooms that are significantly remote from noise sources and vibrations. Protection against structural noise is carried out by the methods of acoustic vibration insulation of engineering equipment and its communications. These methods include the installation of flexible inserts and vibration insulators, facilities for the floors on the elastic base (floating floors).

In the first case, flexible inserts from linen cans are installed to reduce the structural noise of ventilation equipment on the sides of the discharge and suction of the fans. Inserts are manufactured in accordance with typical drawings and have a rectangular and round cross-section. For pumps and refrigeration machines, flexible inserts are used in the form of rubber sleeves.

Another way is to reduce noise through the use of vibration insulators. To achieve a goal in practice, two types of vibration insulators are often used: steel spring and rubber vibration insulators.

Rubber vibration insulators, the maximum allowable static deflection of which is 30% of their height, are used at speeds of more than 1800 rpm. These vibration insulators effectively reduce the transmission of vibration at high frequencies. However, their use does not significantly reduce the transmission of vibration at low frequencies. In addition, rubber vibration insulators have low wear resistance. The most effective is the use of combined vibration insulators consisting of spring vibration insulators, which are installed on rubber or cork pads with a thickness of 10 - 20 mm and fit to the support surface.

The third method is the use of floors on an elastic base (floating floors). Their effectiveness may be lower than in vibration insulators (in the calculated frequency band), but the damping ability of such floors is manifested in a wide frequency range.

In the designs of this type, as in general, when the soundproofing device, it is necessary to strictly monitor the lack of through holes and cracks in insulating structures, a dense adjuncing elements to each other. In the case of "floating floors", the elastic gaskets must go up onto the walls along their perimeter, preventing rigid mechanical contact of the floor (tie) with walls.

It is necessary to note the organizational ways of protection against noise (see below).

The choice of rational modes of operation of the equipment, restricting the time of finding staff in the zone of operation of aggregates (machines) with an increased level of noise (protection "time")

Protection "Time" provides for the premises in rooms with a high level of noise only for the official need for a clear regulation on the time of the actions committed; automation of work; Reducing the time of configuration work, etc.

The duration of additional regulated breaks is set to the level of noise, its spectrum and personal protective equipment. For those groups of workers, where, according to safety conditions, the use of contractions (listening to signals, etc.) is not allowed, only noise levels and its spectrum is taken into account.

Rest in the period of regulated breaks should be carried out in specially equipped facilities. During the lunch break, working when exposed to elevated noise levels should also be in optimal acoustic conditions (when the sound level is not higher than 50 dBA).

Use of personal protection of hearing organs

Anti-liners, anti-checkered headphones and helmets include the means of individual protection of the organ of hearing. The effectiveness of PPE can be ensured by their correct selection depending on the levels and spectrum of noise, as well as to the control of the correct operation.

There are different levels of noise and its permissible norms, the excess of which is of a greater danger to human hearing.

How is noise measured?

The noise level, like sounds, is measured in decibels (dB). Under the Law of the Russian Federation there are established norms that cannot be exceeded. In the daytime - no more than 55 decibels, in the night - no higher than 45 dB. These are extremely valid values, as their increase is negatively affecting human health. The nervous system is mainly suffering, headaches arise.

What is dangerous high sounds?

Noise levels can be different. Some do not exceed the norms established by law and do not interfere with human life. In the daytime, a higher level of sounds is allowed, but it also has its own frames in decibels. If the norm is exceeded, then a person can feel nervousness, irritability. The reactions are braked, performance and intelligence decreases.

Noise Over 70 Decibel can lead to a deterioration of hearing. Especially loud sounds strongly affect the health of kids, disabled people and elderly people. According to studies of the effect of noise per person, the reaction of the nervous system to increase the allowable norms of the sound background begins with 40 decibels. Sleep is broken already at 35 dB.

Strong changes in the nervous system occur with noise in 70 decibels. In this case, a person may have mental diseases, worsen hearing and vision and even change in negative side Blood composition.

For example, in Germany, almost twenty percent workers work with noise from 85 to 90 decibels. And it led to the frequent cases of hearing loss. A constant noise that exceeds the norm entails at least drowsiness, fatigue and irritation.

What happens to hearing under the influence of noise?

Long or excessively loud sound background may damage the human hearing apparatus. The most dangerous at the same time - the breakpoint breakpoint. Accordingly, hearing is reduced or complete deafness occurs. In the worst version with a loud explosion, the sound level of which reaches 200 decibels, the person dies.

Norma

The maximum noise level in the residential premises (at any time of the day) is set according to sanitary requirements. The sound of over 70 decibels is harmful not only for psychological, but also for the physical condition of a person. In enterprises, the noise level is regulated according to sanitary standards and hygienic requirements established in the Russian Federation.

The optimal noise background is considered to be a value of 20 decibels. For comparison: urban noise on average ranges from 30 to 40 dB. And the maximum allowable for airliners is 50 dB over the ground. Now on many urban streets, noise levels reach from 65 to 85 decibels. But the most common indicators are from 70 to 75 dB. And this is at 70 dB.

High noise (dB) is 90. It causes headaches, increases pressure, etc. To zones with an elevated noise level include residential areas near airports, industrial enterprises, etc. In the construction grounds, the permitted norm of increased sounds is not Must exceed 45 decibels.

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

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

The noise levels of low intensity from urban transport, which is heard in residential premises, is approximately equal to 35 decibels. It does not cause physiological shifts in people. When the sound level in 40 decibels, after ten minutes, the change in the hearing sensitivity begins. Under the influence of constant noise, within fifteen minutes of sensation returns to normal. With 40 dB, the duration of calm sleep is slightly disturbed.

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

But mostly people suffer from road noise. In cities where there is a busy transport movement, the sound background somewhat exceeds the norm. During the passage of powerful trucks, noise reaches the maximum value - from 85 to 95 decibels. But on average in big cities exceeding permissible norm hesitates from 5 to 7 decibel. And only in private sectors, the noise load meets the adopted standards.

Technical progress causes an increase in the artificial sound background, which in this case becomes harmful to humans. In some industries, the noise level in the room reaches from 60 to 70 decibels and higher. Although the norm should be a value of 40 dB. All working mechanisms create a large noise distributed over a large distance.

This is especially noticeable in the mountain and metallurgical industry. In such production, the noise reaches the mark from 75 to 80 decibels. From the explosions and work of turbojet engines - from 110 to 130 dB.

What include sanitary noise norms?

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

The norms are based on the characteristics of which noise level, affecting even for a long time, does not cause negative changes in the human body. In the afternoon, this is not more than 40 decibels, and at night - not higher than 30 dB. The permissible limit of transport noise is from 84 to 92 dB. And over time, the established norms of sound background are planned to be reduced yet.

How to determine the noise level?

At night, get rid of loud noise is quite simple. You can cause a precinct or outfit police. But during the daytime, determine the noise level is much more problematic. Therefore, there is a special examination. A special sanitary and epidemiological commission is caused from Rospotrebnadzor. And the outgoing noise is fixed in decibels. After measurements, the act is drawn up.

Noise rates for construction

When building residential buildings, developers are required to provide premises with good sound insulation. Noise should not be more than 50 decibels. This applies to the sounds transmitted by air (working TV, neighbors' conversations, etc.).

Comparative values \u200b\u200bof permissible noise

Short-term under the influence of high-profile sounds up to 60 decibels for a person are not hazardous. Unlike systematic noise, which disrupts the nervous system. Next, noise levels are described (in dB) from various sources:

• human whisper - from 30 to 40;
• refrigerator work - 42;
• lift Cabin Movement - from 35 to 43;
• ventilation "brizer" - from 30 to 40;
• air conditioning - 45;
• the noise of the flying airliner - 140;
• game of piano - 80;
• forest noise - from 10 to 24;
• flowing water - from 38 to 58;
• noise of working vacuum cleaner - 80;
• spoken speech - from 45 to 60;
• supermarket noise - 60;
• car beep - 120;
• cooking on the meal plate - 40;
• noise of motorcycle or train - from 90;
• repair work - 100;
• dance music in nightclubs - 110;
• children's crying - from 70 to 80;
• mortal for man Noise level - 200.

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

Therefore, the rest is important. After work on the production on which the noise level is rapidly, it is necessary to restore hearing. To do this, it is enough to be as much time as possible in relaxing, quiet places. It is well suited to go to nature.

How to measure noise in decibels?

The permissible noise level can be measured independently with the help of special items - noisometers. But they are very expensive. And fixing the level of sounds is made only by specialists, without the conclusion of which acts will be invalid.

As already mentioned above, aggressive noise impact sometimes leads to a rupture drumpocking. For this reason, the rumor worsens, sometimes to a complete deafness. Although the eardrum can recover, but the process is very long and depends on the severity of damage.

For this reason, it is recommended to avoid long-term exposure to noise. Periodically, you need to give the ears to rest: to be in full silence, ride in the village (for the cottage), do not listen to music, turn off the TV. But first of all it is desirable to abandon all sorts of portable music players with headphones.

All this will help save our precious hearing, which will always serve faith and truth. In addition, silence contributes to the restoration of drummers after injury.

Noisecall any unwanted sound or a set of such sounds. The sound is a wave-like oscillating process in the form of alternating waves of thickening and discharge of particles of this medium - sound waves.

Sound source can be any oscillating body. When contacting this body with the environment, sound waves are formed. The concentration waves cause an increase in pressure in an elastic medium, and the discharge waves are a decrease. From here there is a concept sound pressure- This is an alternating pressure resulting from sound waves in addition to atmospheric pressure.

Sound pressure is measured in Pascal (1 Pa \u003d 1 N / m 2). The human ear feels a sound pressure from 2-10 -5 to 2-10 2 N / m 2.

Sound waves are carriers of energy. Sound energy, which falls on 1 m 2 surface area, located perpendicular to the propagating sound waves, called the power of soundand it is expressed in W / m 2. Since the sound wave is a oscillatory process, then it is characterized by such concepts as period of oscillation(T) - the time during which one complete oscillation is performed, and frequency of oscillations(Hz) - the number of fluctuations for 1 s. Combustion frequency gives spectrum noise.

Noise contain sounds of different frequencies and differ in each other by the distribution of levels in certain frequencies and the character of the change general level in time. For the hygienic estimate of noise, the sound frequency range is used from 45 to 11,000 Hz, comprising 9 octave bands with medium-beometric frequencies of 31.5; 63; 125; 250; 500; 1000; 2000; 4000 and 8000 Hz.

The hearing body distinguishes not the difference, but the multiplicity of changes in sound pressures, so the intensity of the sound is considered not to assess the absolute value of sound pressure, but its levelthose. the ratio of the pressure being created to pressure adopted per unit

comparison. In the range from the threshold of hearing to the painful threshold, the ratio of sound pressures varies in a million times, therefore, to reduce the measurement scale, the sound pressure is expressed through its level in the logarithmic units - decibels (dB).

Zero decibel corresponds to sound pressure of 2-10 -5 PA, which approximately corresponds to the threshold of tone hearing with a frequency of 1000 Hz.

The noise is classified according to the following features:

Depending on the character spectrumallocate the following noise:

broadbandwith a continuous spectrum width of more than one octave;

tonalin the spectrum of which there are pronounced tones. The tonal nature of noise is set by measuring in the frequency bands in terms of exceeding the level in one strip compared to neighboring at least 10 dB.

By temporary characteristicsthere are noises:

constantthe sound level of which for an 8-hour working day changes in time for no more than 5 dBA;

non-permanentthe noise level of which for an 8-hour working day changes in time at least 5 dBA. Non-permanent noises can be divided into the following types:

- spatteringin time, the sound level of which continuously changes in time;

- intermittentthe sound level of which stepwise changes (by 5 dB-a and more), and the duration of the intervals during which the level remains constant, is 1 s or more;

- impulseconsisting of one or more audible signals, each of which has a duration of less than 1 s; At the same time, sound levels measured according to the temporal characteristics of the "impulse" and "slowly" noiseomer differ in at least 7 dB.

11.1. Sources of noise

Noise is one of the most common adverse factors of the production environment, the impact of which on employees is accompanied by the development of premature fatigues, a decrease in labor productivity, growth of common and professional morbidity, as well as injuries.

Currently, it is difficult to name the production on which there are no higher levels of noise in the workplace. The most noisy includes mining and coal, machine-building, metallurgical, petrochemical, forestry and well-grained, radiotechnical, light and food, meat and dairy industry, etc.

So, in the cold landing shops, the noise reaches 101-105 dBA, in the cloves - 104-110 dBA, in braid - 97-100 dBA, in the separation of seam polishing - 115-117 dba. In the workplaces of Tokarei, milling workers, motorists, Kuznetsov-stampers, noise level ranges from 80 to 115 dBA.

At the factories of reinforced concrete structures, noise reaches 105-120 dBA. Noise is one of the leading professional hazards in woodworking and logging industries. Thus, at the workplace of the frame and cutter, the noise level ranges from 93 to 100 dBA with a maximum of sound energy in the middle and high frequency domain. In the same limits, noise fluctuates in carpentry shops, and logging works (roll, forest routing) are accompanied by noise level from 85 to 108 dBA due to the work of the skiing winches, tractors and other mechanisms.

The overwhelming majority of industrial processes in spinning and weaving shops are also accompanied by the formation of noise, the source of which is the boiler mechanism of the weaving machine, shuttleties shutters. The highest noise is observed in weaving shops - 94-110 dBA.

Studying working conditions on modern sewing factories has shown that the noise level in the workplace of the SWE-Motorest is 90-95 dB with the maximum sound energy at high frequencies.

The most noisy operations in mechanical engineering, including aircraft engineering, automotive, car buildings, etc. It should be considered hard and riveting work using pneumatic instruments, mode tests of engines and their units of various systems, bench tests for the vibrational products, drum cooking, grinding and polishing Details, stampress preparation.

For the petrochemical industry, high-frequency noises of various levels are characteristic due to the discharge of compressed air from the closed technological cycle of chemical industries or

from equipment running on compressed air, such as assembly machines and vulcanization lines of tire plants.

At the same time, in mechanical engineering, as in any other industry, the largest volume of works falls on machine metalworking, where about 50% of all working industries are employed.

The metallurgical industry as a whole can be attributed to the industry with a pronounced noise factor. Thus, intense noise is characteristic of melting, rolling and pipe rolling industries. From the industries relating to this industry, the noisy conditions are characterized by hardware plants equipped with colder machines.

The most noisy processes include noise from an open air jet (blowing), breaking out of the holes of the small diameter, noise from gas burners and the noise formed when spraying metals on various surfaces. Spectra from all these sources is very similar, typically high-frequency, without a noticeable recession of energy to 8-10 kHz.

Woodworking workshops are the most noisy and pulp and paper industries.

The building materials industry includes a number of noisy industries: machines and mechanisms for crushing and grinding of raw materials and the production of precast concrete.

In the mining and coal industries, the operations of mechanized mining of minerals both using manual machines (pneumoperphorators, jackhammers) and with the help of modern stationary and self-propelled machines (combines, drilling machines, etc.) are the most noisy.

The radiotechnical industry is generally relatively less noisy. Only preparatory and preparatory workshops are equipped with equipment characteristic of the machine-building industry, but in a much smaller quantity.

In the light industry both by noise and in the number of employed workers most unfavorable are spinning and weaving productions.

Food industry - the least noisy of all. Characteristic noise generates stream units of confectionery and tobacco factories. However, individual machines of these industries create significant noise, for example, cocoa grain mills, some sorting machines.

Each industry has a workshop or individual compressor stations, supplying compressed air or pumping liquids or gaseous products. The latter are of great distribution in the gas industry as large independent farms. Compressor installations create intensive noise.

Examples of noise characteristic of various industries, in the absolute majority of cases have a common form of spectra: all of them are broadband, with some spage of sound energy in the low (up to 250 Hz) and high (above 4000 Hz) frequencies with levels of 85-120 dBA. The exceptions are noises of aerodynamic origin, where the levels of sound pressure grow from low to high frequencies, as well as low-frequency noise, which in industry compared to those described above are significantly less.

All the noise described characterizes the most noisy production and sections, where physical work is mainly dominated. At the same time, the noise less intense (60-80 dBA) are widely common, which, however, is hygienically meaningful in operations associated with the nervous load, for example, on the control panels, with the machine processing of information and other works that are increasingly distributed.

Noise is also the most characteristic adverse factor in the production environment at the workplaces of passenger, transport aircraft and helicopters; rolling stock of rail transport; marine, river, fishing and other ships; buses, cargo, passenger and special cars; agricultural machinery and equipment; Building, reclamation and other machines.

Noise levels in the cabins of modern aircraft fluctuate in a wide range - 69-85 dBA (main airplanes for airlines with medium and large range). In the cabins of car medium loading capacity at various modes and conditions of operation, the sound levels are 80-102 dBA, in the cabins of heavy vehicles - up to 101 dBA, in passenger cars - 75-85 dBA.

Thus, it is important for the hygienic assessment of noise, it is important to know not only its physical parameters, but also the nature of the human operator's work activity, and, above all, the degree of its physical or nervous load.

11.2. Biological effect of noise

Professor E.TS. made a great contribution to the study of the problem of noise. Andreeva-Galanina. She showed that noise is a common stimulus and affects not only the hearing analyzer, but, in the first place, acts on the structures of the brain, causing shifts in various systems of the body. Manifestations of the noise impact on the human body can be conditionally divided into specificchanges coming in the organ of hearing, and nonspecificarising in other organs and systems.

Aural effects. Changes in the sound analyzer under the influence of noise are the specific reaction of the body on acoustic effect.

It is generally recognized that the leading sign of the unfavorable effect of noise on the human body is a slowly progressive reduction of hearing in the type of cochlear neuritis (as a rule, both ears suffer to the same extent).

Professional decline in hearing refers to the sensorsulene (perceptual) hearing loss. Under this term implies a violation of hearing of a sound pending character.

Reducing the hearing influenced by fairly intensive and long-acting noise is associated with degenerative changes in both the Cortiyev Cortium cells and the first neuron of the auditory path - a spiral ganglia, as well as in the fibers of a cochlear nerve. However, there is no uniform opinion about the pathogenesis of persistent and irreversible changes in the receptor department of the analyzer.

Professional touginess usually develops after a more or less long period of operation in noise. The timing of its occurrence depend on the intensity and frequency-time parameters of noise, the duration of its impact and the individual sensitivity of the hearing body to noise.

Complaints on headache, increased fatigue, noise in ears, which may arise in the first years of work under noise conditions are not specific to damage the auditory analyzer, but rather characterize the reaction of the CNS to the effect of the noise factor. The feeling of decrease in hearing usually occurs significantly later than the appearance of the first audiological signs of the destruction of the auditory analyzer.

In order to detect the earliest signs of noise on the body and, in particular, on the sound analyzer, the most widely used method for determining the temporary displacement of the hearing thresholds (VSD) with different exposure durations and noise character.

In addition, this figure is used to predict hearing loss on the basis of the relationship between the constant impacts of the thresholds (losses) of the hearing (PSP) from the noise operating during the entire operation time in noise, and temporary shifts of thresholds (VSP) during the day exposure of the topics The same noise measured two minutes after the exposure to noise. For example, weak time displacements of the hearing thresholds at a frequency of 4000 Hz for the daily exposure of the noise are numerically equal to constant hearing loss at this frequency for 10 years of work in the same noise. Based on this, you can predict the resulting hearing loss, determining only the shift of the threshold for the daily exposure of noise.

The noise accompanied by vibration is more harmful to the organ of hearing than is isolated.

Extraural effect of noise. The idea of \u200b\u200bnoise disease was developed in 1960-70. On the basis of work on the effect of noise on cardiovascular, nervous, etc. Systems. Currently, it was replaced by the concept of extra -ural effects as non-specific manifestations of noise.

The workers exposed to noise make complaints of headaches of various intensity, often with localization in the forehead area (more often they arise by the end of work and after it), dizziness associated with the body position variable, depending on the effect of noise on the vestibular device, reducing memory , drowsiness, increased fatigue, emotional instability, sleep disorder (intermittent sleep, insomnia, less often drowsiness), pain in the heart, decline in appetite, increased sweating, etc. The frequency of complaints and their severity depend on the work experience, the intensity of noise and its nature. .

Noise can break the function of the cardiovascular system. Changes in the electrocardiogram in the form of shortening the Q-T interval, lengthening the interval P-q, increase the duration and deformation of the teeth P and S, the displacement of the interval T-S, the change in the voltage of the T. T.

The most unfavorable in terms of the development of hypertensive states is broadband noise with the predominance of high-frequency components and a level of over 90 dBA, especially impulse noise. Broadband noise causes maximum shifts in peripheral blood circulation. It should be borne in mind that if there is an addictive (adaptation) to the subjective perception of noise, it is not observed in relation to developing vegetative adaptation reactions.

According to the epidemiological examination of the prevalence of basic cardiovascular diseases and some risk factors (excessive mass, burdened history, etc.) in women working under the impact of constant production noise in the range from 90 to 110 dBA, it is shown that noise as separately taken factor (excluding common risk factors) may increase frequency arterial hypertension (AG) In women under the age of 39 years (with more than 19 years), only 1.1%, and women over 40 years old - by 1.9%. However, with a combination of noise, at least one of the "common" risk factors can be expected to be expected by 15%.

When exposed to intensive noise 95 dBA and above, a violation of vitamin, carbohydrate, protein, cholesterol and water-salt exchanges may occur.

Despite the fact that noise affects the body as a whole, the main changes are observed by the hearing body, central nervous and cardiovascular systems, and changes in the nervous system may precede violations in the hearing body.

Noise is one of the strongest stressful production factors. As a result of the impact of high intensity noise, changes both in neuroendocrine and in immune systems are simultaneously arising. In this case, stimulation of the front lobe of the pituitary gland and an increase in secretion by the adrenal glands of steroid hormones, and, as a result of this, the development of the acquired (secondary) immunodeficiency with the involution of lymphoid organs and significant changes in the content and functional state of T- and B-lymphocytes in the blood and bone marrow are the development of (secondary) immunodeficiency. Arising defects immune system Connect mainly three main biological effects:

Reduction of anti-infectious immunity;

Creation of favorable conditions for the development of autoimmune and allergic processes;

Reducing antitumor immunity.

The relationship between the incidence and the magnitude of the hearing loss in speech frequencies of 500-2000 Hz is proven, indicating that changes contributing to a decrease in the resistance of the organism simultaneously with a decrease in hearing. With an increase in production noise by 10 dBA, the indicators of the overall incidence of working (both in cases and in days) increase in 1.2-1.3 times.

Analysis of the dynamics of specific and nonspecific disorders with an increase in work experience with noise effects on the example of weaving showed that a polymorphic symptom complex is formed in tapes in tapes, including pathological changes in the hearing body in combination with vegetary-seeking dysfunction. At the same time, the growth rate of hearing losses is 3.5 times higher than the increase functional disorders nervous system. With an experience of 5 years, transient vegal impairment predominate, with more than 10 years - hearing loss. The relationship of the frequency of vegetation dysfunction and the magnitude of the hearing loss is also revealed, which manifests itself in their growth when the hearing is reduced to 10 dB and in stabilization during the progression of hearing loss.

It has been established that in industries with noise levels up to 90-95 dBA, vegetative-vascular disorders appear earlier and are translated over the frequency of cochlear neurites. The maximum development is observed at a 10-year work experience in noise. Only at noise levels exceeding 95 dBA, by 15 years of work in the "noisy" profession, extra -ural effects are stabilized, and the phenomena phenomena begin to prevail.

Comparison of the frequency of hearing loss and neuro-vascular disorders depending on the noise level showed that the growth rate of hearing loss is almost 3 times higher than the growth rate of neuro-vascular disorders (respectively, about 1.5 and 0.5% per dBA), that is, With increasing noise level of 1 dB, hearing loss will increase by 1.5%, and neuro-vascular disorders are 0.5%. At levels of 85 dBA and above for each noise decibel, neuro-vascular disorders occur for half a year earlier than at lower levels.

Against the background of occurring intellectualization of labor, the growth of the specific gravity of the operator professions is noted to increase the meaning of the noise of the average levels (below 80 dBA). These levels do not cause hearing losses, but, as a rule, it is distinguished by interfering, annoying and tiring actions that are summed up with

such from tense labor and with an increase in the experience of work in the profession can lead to the development of extracurral effects that manifest themselves in general general disorders and diseases. In this regard, the biological equivalent of actions on the body of noise and neuro-strained work was justified, equal to 10 dB of noise per category of the labor process (Suvorov G.A. et al., 1981). This principle is based on the active sanitary standards for noise differentiated taking into account the tensions and severity of the labor process.

Currently, much attention is paid to the assessment of the professional risks of the health of working, including those caused by the adverse effects of industrial noise.

In accordance with ISO 1999.2 Standard "Acoustics. Determination of the professional effects of noise and evaluating hearing impairment caused by noise »can evaluate the risk of hearing disorders depending on the exposure and predict the likelihood of occupational diseases. Based on the mathematical model of the ISO standard, the risks of the development of professional hearing loss in percentage, taking into account the domestic criteria of professional hearing loss (Table 11.1). In Russia, the degree of professional hearing loss is estimated at the average hearing loss in three speech frequencies (0.5-1-2 kHz); The values \u200b\u200bof more than 10, 20, 30 dB correspond to the 1st, II, III-C degree of rumor reduction.

Considering that the decline hearing I-th The degrees with rather highly likelihood can develop and without noise effects as a result of age-related changes, it seems inappropriate to use the I-Ju degree of hearing decline to assess the safe experience of the work. In this regard, the table presents the calculated working experiences, during which hearing loss of II and III degree may develop depending on the level of noise in the workplace. Data is given for different probabilities (in%).

IN table. 11.1.the data for men are given. In women, due to a slower, than in men, the increase in age-related hearing changes, the data is slightly different: for the experience of more than 20 years, there are more facial experience for 1 year more than in men, and for more than 40 years - for 2 years .

Table 11.1.Work experience before the development of hearing losses exceeding

criterial values, depending on the noise level in the workplace (at 8-hour exposure)

Note. digger means that the work experience is over 45 years.

At the same time, it should be noted that the standard does not take into account the nature of labor activity, as provided for in the noise sanitary standards, where the maximum permissible levels of noise are differentiated by categories of gravity and tensions of labor and thereby cover the nonspecific effect of noise, which is important to preserve health and health. persons operator professions.

11.3. Normation of noise at workplaces

The prevention of the unfavorable effect of noise on the body of working is based on its hygienic rationing, the purpose of which is to substantiate the permissible levels and the complex of hygienic requirements that ensure the prevention of functional disorders or diseases. In hygienic practice, extremely permissible levels (remote control) for jobs that allow deterioration and change of external activity indicators (efficiency are used as a rationing criterion

and performance) with a mandatory return to the previous system of homeostatic regulation of the source functional state, taking into account adaptation changes.

Noise rationing is carried out according to the complex of indicators, taking into account their hygienic significance. The effect of noise on the body is evaluated by reversible and irreversible, specific and non-specific reactions, a decrease in operability or discomfort. To preserve the health, performance and well-being of a person, the optimal hygienic rationing should take into account the type of labor activity, in particular, the physical and non-surreimed components of labor.

The impact of the noise factor on a person consists of two components: load on the hearing body as a system that perceive sound energy is auraral effectand impact on the central links of the sound analyzer as a system for receiving information - extraural effect.To estimate the first component there is a specific criterion - "fatigue of an hearing body", expressed in the displacement of the thresholds of the perception of tones, which is proportional to the magnitude of the sound pressure and the exposure time. The second component was named nonspecific influencewhich one can objectively assess the integral physiological indicators.

Noise can be considered as a factor involved in the efferent synthesis. At this stage in nervous system The comparison of all possible efferent influences (decorating, reverse and search) in order to develop the most adequate response. The effect of strong production noise is such a factor of the external environment, which by its nature also affects the efferent system, i.e. It affects the process of forming a reflex reaction in the effect of effectant synthesis, but as a flat-end factor. At the same time, the result of the possibility of the situation and starting effects depends on their strength.

In cases of installation on activities, the situation should be an element of stereotype and, therefore, do not cause adverse changes in the body. At the same time, the grave to noise in the physiological sense is not observed, the severity of fatigue and the frequency of nonspecific disorders increases with an increase in the experience of working in noise. Consequently, the mechanism of action of noise can not be limited by the participation factor in

placement afferentation. In both cases (noise and voltage), we are talking about the load on the functional systems of the highest nervous activity, and, consequently, the genesis of fatigue with such an impact will be similar.

Criterion for rationing at an optimal level for many factors, including for noise, one can consider such a state. physiological functionsAt which this noise level does not contribute to their voltage, and the last entirely determined by the work performed.

Labor tension consists of elements included in the biological system of reflex activity. Analysis of information, the amount of RAM, emotional voltage, functional voltage of analyzers - all these elements are loaded in the process of work, and naturally, their active load causes the development of fatigue.

As in any case, the response to the impact consists of the components of specific and non-specific characters. What is the proportion of each of these elements in the process of fatigue - the question is unresolved. However, there is no doubt that the impact of noise and tensions of labor cannot be considered one excluding the other. In this regard, the effects mediated through the nervous system (fatigue, reduction of working capacity), both for noise and for labor tensions have high-quality similarities. Industrial and experimental studies using socio-hygienic, physiological and clinical methods and indicators confirmed these theoretical provisions. On the example of the study of different professions, the magnitude of the physiological and hygienic equivalent of noise and the tension of neuro-emotional labor, which was within 7-13 dba, i.e. On average 10 dBA per one category of tension. Therefore, an assessment of the operator's labor process intensity is necessary for a full hygienic assessment of the noise factor in the workplace.

Maximum permissible levels of sound and equivalent levels of sound at workplaces, taking into account the tensions and severity of labor activity are presented in table. 11.2.

A quantitative assessment of the severity and strength of the employment process should be carried out in accordance with the criteria of the Guide 2.2.2006-05.

Table 11.2.Maximum permissible sound levels and equivalent sound levels on workplaces for labor activities of different categories of gravity and tension, dBA

Note.

For tonal and impulse noise, the remote control of 5 dBAs is less than the values \u200b\u200bspecified in the table;

For noise created in the rooms of air conditioning installations, ventilation and air heating, I remove 5 dBA less actual levels of noise in rooms (measured or calculated) if the latter do not exceed the valuestable. 11.1. (the correction for tonal and impulse noise is not taken into account), otherwise - by 5 dBa less than the values \u200b\u200bspecified in the table;

Additionally, the maximum sound level should not exceed 110 dBA, and for pulse noise - 125 dBa for pulse noise.

Since the purpose of differentiated rationing of noise is the optimization of working conditions, which occurred combined and very tense with severe and very difficult physical labor are not normalized on the basis of the need for their elimination as unacceptable. However, for the practical use of new differentiated norms, both in the design of enterprises and under the current control over noise levels on existing enterprises, a serious problem is to bring the categories of gravity and labor tensions with the types of work and work premises.

Pulse noise and its assessment. The concept of impulse noise is not strictly defined. Thus, in existing sanitary standards, the impulse noise includes noise consisting of one or more sound signals, each duration of less than 1 s, while the levels of sound in dBA, measured according to the characteristics of the "pulse" and "slowly", differ in at least 7 dB.

One of the important factors determining the difference in reactions to constant and impulse noise is the peak level. In accordance with the concept " critical level»Noise with levels above defined, even very short-term, can cause direct injury to the organ of hearing, which is confirmed by morphological data. Many authors indicate different critical level values: from 100-105 dBA up to 145 dBA. Such noise levels are found at work, for example, in blacksmithing shops, the noise from the hammer reaches 146 and even 160 dBA.

Apparently, the danger of impulse noise is determined not only by high equivalent levels, but also an additional contribution of the time characteristics is likely due to the traumatic effect of high peak levels. The distribution of pulse noise levels have shown that, despite the small total response time of peaks with levels above 110 dBA, their contribution to the total dose can reach 50%, and this value of 110 dBA was recommended as an additional criterion in assessing non-permanent noise to the remote control. Sanitary standards.

The above rules are set to 10 dB pulsed noise lower than for permanent noise (i.e., minus 5 dba is made at an equivalent level), and additionally limit the maximum sound level of 125 dB "pulse", but do not regulate peak values. Thereby existing norms

focus on the loud effects of noise, since the characteristic of the "pulse" with T \u003d 40 ms is adequate to the upper parts of the sound analyzer, and not a possible traumatic action of its peaks, which is generally accepted at present.

Noise impact on working, as a rule, is non-permanent in terms of noise and (or) time of its action. In this regard, a concept has been introduced to evaluate non-permanent noise equivalent sound level.The equivalent level is associated with the dose of noise, which reflects the amount of transmitted energy and therefore can serve as a measure of noise load.

The presence in the current sanitary standards of noise in the workplace, in the premises of residential and public buildings and on the territory of residential buildings as a normalized parameter of the equivalent level and the absence of noise as a dose of noise is explained by a number of factors. First, the lack of domestic dosimeters in the country; Secondly, when measuring noise for residential premises and for some professions (workers, whose hearing body is a working body), the energy concept requires corrections made to the measuring instruments, for noise expressions not in sound pressure levels, but in the values \u200b\u200bof the subjective volume.

Given the emergence of a new direction in hygienic science in recent years to establish the degree of professional risk from various factors of the production environment, including noise, should be taken into account in the future, the amount of noise dose with various risk categories is not so much on specific influence (auditory), but Non-specific manifestations (violations) by other organs and systems of the body.

To date, the effect of noise per person has been studied isolated: in particular, industrial noise - on workers of various industries, employees of the administrative and administrative apparatus; Urban and housing noise - on the population of various categories in living conditions. These studies allowed to justify the standards for a permanent and non-permanent, industrial and household noise in various places and the conditions of the person's stay.

However, for the hygienic assessment of the effects of noise on a person in industrial and outgoing conditions, it is advisable to take into account the total noise effect on the body that

possible on the basis of the concept daily dose Noise, taking into account the types of human life (work, rest, sleep), based on the possibility of cumulating their effects.

11.4. Prevention of unfavorable noise

Activities for combating noise can be technical, architectural planning, organizational and medical and prohydration.

Technical means of combating noise:

Eliminate the causes of noise or reduced it in the source;

Weakening of noise on transmission paths;

The direct protection of the working or group of workers from the effects of noise.

Most effective tool Noise reduction is to replace noisy technological operations on low noise or completely silent. Of great importance is the reduction of noise in the source. This can be achieved by improving the design or installation scheme that produces noise, changing the mode of its operation, the equipment of the noise source with additional soundproofing devices or fences located as close to the source (within its near-field). One of the easiest technical means Combating noise on transmission paths is a soundproofing casing that can close a separate noisy machine knot (for example, gearbox) or the entire unit as a whole. Shells made of sheet metal with inner cladding sound-absorbing material can reduce noise by 20-30 dB. The increase in the soundproofing of the casing is achieved by applying to its surface of vibration-absorbing mastic, which reduces the levels of vibration of the casing in resonant frequencies and rapid attenuation of sound waves.

To reduce aerodynamic noise generated by compressors, ventilation installations, pneumatic transport systems, etc., the silencers of active and reactive types are used. The most noisy equipment is placed in soundproofing chambers. With large dimensions of the machines or a significant service zone, equip special cabins for operators.

Acoustic finishing of premises with noisy equipment can provide noise reduction in the reflected audio field area by 10-12 dB and in the direct sound area up to 4-5 dB in octave frequency bands. The use of sound-absorbing cladding for the ceiling and walls leads to a change in the noise spectrum towards lower frequencies, which even with a relatively small reduction in the level significantly improves the working conditions.

In the multi-storey industrial buildings, the protection of premises from structural noise(extending the construction of the building). Its source can be manufacturing equipment that has a tough connection with enclosing structures. The weakening of the transfer of structural noise is achieved by vibration insulation and vibration absorption.

Good protection against shock noise in buildings is the device "floating" floors. Architectural and planning solutions in many cases predetermine the acoustic regime of industrial premises, facilitating or making it difficult to solve problems for their acoustic improvement.

The noise regime of industrial premises is due to dimensions, shape, density and types of arrangement of machines and equipment, the presence of a sound-absorbing background, etc. Planning activities should be directed to the localization of sound and reduce its distribution. Rooms with sources high level Noise, if possible, should be grouped in one zone of the building adjacent to warehouse and auxiliary premises, and separated by PAI corridors with utility rooms.

Considering that with the help of technical means it is not always possible to reduce noise levels in the workplace to regulatory values, it is necessary to apply the means of individual protection of the hearing organ from noise (antifones, plugs). The effectiveness of personal protective equipment can be ensured by the correct selection depending on the levels and spectrum of noise, as well as control over the conditions of their operation.

In the complex of measures to protect a person from the unfavorable action of noise, a certain place occupy medical means Prevention. The most important importance is the conduct of preliminary and periodic medical examinations.

Contraindications for a reception to work, accompanied by noise effect, serve:

Persistent decrease in hearing (at least one ear) of any etiology;

Otosclerosis and others chronic diseases ear with an unfavorable forecast;

Violation of the function of the vestibular apparatus of any etiology, including the Menietor's disease.

Taking into account the value of the individual sensitivity of the body to noise, the dispersonal observation of the working first year of work under noise work is extremely important.

One of the directions of individual prophylaxis of noise pathology is to increase the resistance of the body of workers to the unfavorable action of noise. For this purpose, the working noisy professions is recommended daily reception of group vitamins in in an amount of 2 mg and vitamin C in the amount of 50 mg (the duration of the course 2 weeks with a break per week). It should also be recommended to introduce regulated additional interruptions, taking into account the level of noise, its spectrum and the availability of personal protective equipment.

Lecture 9.

Production and protection against industrial noise, infra- and ultrasound

1. Production noise rationing 1

2. Noise control 2

3. Ultrasound. Rationing and protection 5

4. Infrashuk. Rationing and protection 6

Control questions 6.

1. Production noise rationing

When measuring noise, two methods are used: rationing at the limiting noise spectrum and normalization of the sound level in the dBA.

Rationing at the limit spectrum. This method is basic for constant noise. There are normal levels of sound pressures in 8 octave frequency bands with FSg \u003d 63, 125, 250 ... 8000 Hz. A combination of eight permissible sound pressure levels is called a limit spectrum (PS) - see Fig.1.

For each category of jobs (design bureaus, laboratories, workshops, etc.), its limit spectrum of noise is regulated. Permissible levels of sound pressure at workplaces are given in GOST 12.1.003-.

From the figure it is clear that with increasing frequency, permissible levels are reduced. Each of the spectra has its own index, for example, PS-75, where "75" is the permissible level of sound pressure in an octave strip with a medium-meter frequency of 1000 Hz.

Rationing of sound level in dba. This method is used to estimate constant and non-permanent noise when we do not know the noise spectrum. The sound level is measured in decibels A (dBA) with a sound leisure operating in frequency response mode A, which, as it were, "models" the sensitivity of a human hearing analyzer, which, as is known, has a maximum in the range of 3-5 kHz.

Sound level (DBA) is associated with a limit spectrum addiction

For tonal and impulse noise, permissible levels should be taken by 5 dB less regulatory for constant noise.

Fig. 2. The sensitivity curve of the hearing analyzer and the characteristic of the noiseomer BUT

D. = P. A. 2  T.

where R BUT - Sound pressure corresponding to the measured sound level in the dBA.

A permissible noise dose - dose corresponding to the permissible level of sound or permissible equivalent sound level.

For non-permanent noise, the normalized parameter is equivalent (by energy) the sound level of broadband, permanent and non-impulse noise that has the same effect on a person (L A eq. DB. This level is measured by special integrating noiseomers.

1. Methods of combating noise

When designing new enterprises, industrial premises, it is necessary to take measures to make noise in the premises exceeding the permissible values. The development of measures to combat noise should be preceded by an acoustic calculation. His tasks are:

Determining the level of sound pressure at the calculation point (RT) when the noise source is known and its noise characteristics;

Calculation of the necessary reduction in noise.

The following methods are used to combat noise:

Reducing noise in the source (i.e. "" protection quantity ")

The fight against the noise in the source (by reducing the sound power level of LP) is the most rational one. Specific events here depend on the nature of noise (mechanical, aerohydrodynamic, electromagnetic). So a decrease in mechanical noise can be achieved by improving technological processes and equipment. To reduce aerohydrodynamic noise, it should strive to reduce the velocity of the body flow of the medium (gas or liquid), to improving the aerodynamic qualities of streamlined tel. Reducing electromagnetic noise is achieved through constructive changes in electrical machines. For example, in transformers it is necessary to use a more dense pressing of packets, use damping materials.