The noise is a messy combination of sounds of different heights and volume, causing an unpleasant subjective feeling and objective changes in organs and systems.

The noise consists of individual sounds and has a physical characteristic. The wave propagation of the sound is characterized by a frequency (expressed in hertz) and by force, or intensity, i.e., the amount of energy carried by the sound wave for 1 s after 1 cm2 surface perpendicular to the direction of sound propagation. The power of sound is measured in energy units, most often in Erghah per second per 1 cm2. Erg is equal to 1 din, i.e., the power of the mass, weighing in 1 g acceleration in 1 cm2 / s.

The unit of sound pressure is a bar responding to 1 din by 1 cm2 of the surface and equal to 1/1 000 000 precipitation of atmospheric pressure. The speech of the usual volume creates pressure of 1 bar.

The smallest sound of the sound, which is perceived by a person, is called the threshold of hearing the audio.

Thresholds of hearing for sounds with different frequency of unequal. The smallest thresholds have sounds with a frequency of 500 to 4000 Hz. Outside this range of thresholds of hearingness increase, which indicates a decrease in sensitivity.

The increase in the physical power of the sound is subjectively perceived as an increase in volume, but this occurs to a certain limit, above which the painful pressure in the ears is felt - the threshold of the painful sensation, or the threshold of the touch. With a gradual increase in the sound of sound from the threshold of hearing to the painful threshold, the features of the auditory perception are found: the loudness of the sound increases not in proportion to the growth of its sound energy, but much slower.

For a quantitative assessment of sound energy, a special logarithmic scale of sound power levels in Blue or decibelch is proposed. In this scale for zero, or the initial level, force (10-9 erg / cm2 h / cm or 2 h 10-5 W / cm2 / s), approximately equal to the threshold of audio audio with a frequency of 1000 Hz, which is accepted in acoustics For standard sound. Each stage of such a scale called white corresponds to a change in the power of the sound of 10 times.

If you express the sound strength of the sound with a frequency of 1000 Hz from the threshold of hearability to the painful threshold, then the entire range on the logarithmic scale will be 14 white.

On the spectral composition, all noises are divided into 3 classes.

Class 1. Low-frequency (noise noise units of unwitting, noise penetrating through soundproof obstacles).

Class 2. The mid-frequency noises (the noise of most machines, machines and units of the unaware action).

Class 3. High-frequency noise (ringing, hissing, whistling noise, characteristic of shock-action units, air and gas streams, aggregates acting with high speeds).

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  Hygienic characteristic noise. Noise It is called messy combination of sounds of different heights and volume ...


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  Hygienic characteristic noise (Silence). Distinguish noise: 1) broadband with a continuous spectrum of more than 1 octaves


• 
  Hygienic characteristic noise. Noise It is called a messy combination of sounds of different heights and volume that causes an unpleasant ... more. "


• 
  Hygienic characteristic noise (Silence). Distinguish noise: 1) broadband with a continuous spectrum of more than 1 octaves; 2) Tonal.



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  By temporary characteristics noise There are constant, intermittent, impulse., Ice. in
  For practical purposes, convenient is characteristic Sound measured in decibels.


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  Characteristic physical factors Habitat environment.
  a sharp drops of air humidity level - increased dust and gas supply. noise, infrasound ...

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.

Noises contain sounds of different frequencies and differ in each other by the distribution of levels in separate frequencies and the nature of the change in the total 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 noises:

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 sound pressure levels grow from low to high frequencies, as well as low-frequency noises, 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 railway 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 impairment (intermittent sleep, insomnia, less often drowsiness), pain in the heart, decline in appetite, enhanced sweating and others. The frequency of complaints and their severity depend on the experience of the work, the intensity of noise and its character.

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 the frequency of arterial hypertension (AG) in women under 39 years old (with experience less than 19 years) only by 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. At the same time, there is stimulation of the front lobe of the pituitary and an increase in secretion by adrenal glands steroid hormonesAs 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. 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 in functional disorders of the 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, II I-th degree Reducing hearing.

Considering that the decline in hearing of the I-th degree is quite highly likely to develop and without noise effects as a result of age-related changes, it seems inappropriate to use the I-Ju degree of hearing reduction 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 sanitary standards for noise, where the extremely permissible levels Noise is differentiated by categories of gravity and tensions of labor and thereby cover the nonspecific effect of noise, which is important to preserve the health and performance of 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 functional systems Higher nervous activity, and, consequently, the genesis of fatigue with such an impact will be similar.

The criterion for the optimal level for many factors, including for noise, one can consider such a state of physiological functions, at 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 the noise created in the premises of air conditioning installations, ventilation and air heating, the removal of 5 dBA is less than the actual noise levels in the 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 of the "critical level" of noise with levels above a certain, 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 raw noise effects, since the characteristic of the "pulse" with T \u003d 40 ms is adequate upper departments The sound analyzer, and not possible traumatic action of his peaks, which is generally accepted at the present time.

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

it is possible on the basis of the concept of a daily dose of noise, taking into account the types of human life (work, rest, sleep), based on the possibility of cumulation of 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 most simple technical means of dealing with noise on the transmission paths is a soundproofing casing that can close a separate noisy machine assembly (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 a complex of measures to protect a person from adverse action of noise, a certain place is occupied by medical 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.