Industrial noise is characterized by the following frequency range interval. Summary: Industrial noise and its impact

General information In various sectors of the economy at enterprises and firms there are sources of noise, equipment, machines whose operation is accompanied by noise of human flows. Workers who are constantly in these conditions are exposed to noise that is harmful to their body and reduces labor productivity. Long-term exposure to noise can lead to the development of such an occupational disease as noise sickness. The tonal nature of the noise is established by measuring in one-third octave frequency bands by ...

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58. Industrial noise. Measures to combat it.

1 General

In various sectors of the economy, at enterprises and firms, there are sources of noise - these are equipment, machines, the work of which is accompanied by noise, and human flows. Personnel, workers, and operators who are constantly in these conditions are exposed to noise that is harmful to their body and reduces labor productivity. Long-term exposure to noise can lead to the development of such an occupational disease as "noise sickness".

Noise as a hygienic factor is a set of sounds that adversely affect the human body, interfering with his work and rest.

As with any wavelike vibrational motion, the main parameters characterizing sound are the vibration amplitude, propagation velocity and wavelength.

One of the main characteristics of oscillatory motion is change over time. The time during which the oscillating body makes one full oscillation is called the oscillation period (T) and is measured in seconds.

Oscillation frequency (f) is the number of complete oscillations performed in one second. The unit of measurement for frequency, hertz (Hz), is equal to one vibration per second.

The distance over which a wave process can propagate within one second is called the speed of sound and is denoted by "c".

The distance between two adjacent condensations or rarefions in the sound field characterizes the wavelength (), which is measured in meters.

The propagation of sound waves is accompanied by the transfer of energy in space. The amount of energy passing through a unit of surface located perpendicular to the direction of propagation of a sound wave, per unit of time, is called the intensity or strength of sound.

2 Classification of noise

Noises are classified according to the nature of the spectrum, time characteristics and duration.

By the nature of the spectrum, noise is distinguished: broadband — having a continuous spectrum more than 1 octave wide; tonal - in the spectrum of which there are audible discrete tones. The tonal nature of the noise is established by measuring in one-third octave frequency bands by the excess of the level in the 1st band over the adjacent ones by at least 10 dB.

According to the time characteristics, there are: constants — the sound level of which over an 8-hour working day changes in time by no more than 5 dB (A) when measured on the "Slow" time characteristic of the sound level meter according to GOST 17187; non-constant — the sound level for an 8-hour working day changes in time by at least 5 dB (A) when measured on the "Slow" time characteristic of the sound level meter in accordance with GOST 17187.

By duration (non-constant noises) are distinguished: oscillating in time - the sound level of which is continuously changing in time; intermittent - the sound level of which drops sharply to the background noise level, and the duration of the intervals during which the level remains constant and exceeds the background noise level is 1 s or more; pulse - consisting of one or more sound signals, each with a duration of less than 1 s; in this case, the sound levels, dB (A), measured when the characteristics "Slow" and "Impulse" of the sound level meter according to GOST 17187 are switched on, differ by at least 10 dB.

3 Effects of noise on the human body

Prolonged exposure to intense noise can lead to irritation of the cells of the sound analyzer and its fatigue, and then to a permanent decrease in hearing acuity.

The peculiarities of its impact significantly depend on the excess of the impulse level over the rms level, which determines the noise background at the workplace.

The development of occupational hearing loss depends on the total time of exposure to noise during the working day and the presence of pauses, as well as the total length of service. The initial stages of occupational injury are observed in workers with an experience of 5 years, pronounced (hearing impairment at all frequencies, impaired perception of whispering and colloquial speech) - over 10 years.

In addition to the effect of noise on the organs of hearing, its harmful effect on many organs and systems of the body has been established, primarily on the central nervous system, functional changes in which occur earlier than a violation of auditory sensitivity is diagnosed. Damage to the nervous system under the influence of noise is accompanied by irritability, weakening of memory, apathy, depressed mood, changes in skin sensitivity and other disorders, in particular, the speed of mental reactions slows down, sleep disorders occur, etc. quality and performance.

The effect of noise can lead to diseases of the gastrointestinal tract, changes in metabolic processes (disruption of basic, vitamin, carbohydrate, protein, fat, salt metabolism), disruption of the functional state of the cardiovascular system. Sound vibrations can be perceived not only by the hearing organs, but also directly through the bones of the skull (the so-called bone conduction). When exposed to very high noise levels (more than 145 dB), rupture of the tympanic membrane is possible.

Thus, exposure to noise can lead to a combination of occupational hearing loss (neuritis of the auditory nerve) with functional disorders of the central nervous, autonomic, cardiovascular and other systems, which can be considered an occupational disease - noise sickness. Occupational neuritis of the auditory nerve (noise sickness) is most often found in workers in various branches of mechanical engineering, the textile industry, etc. other professional groups exposed to intense noise for a long time.

5 Ways and means of dealing with noise

When developing technological processes, designing, manufacturing and operating machines, industrial buildings and structures, as well as organizing a workplace, all necessary measures should be taken to reduce noise, ultrasound and vibration at the workplace to values ​​that do not exceed the permissible values ​​specified in GOST 12.1. 003 and GOST 12.1.001.

These measures should be carried out: technical means of controlling noise (reducing the noise of machines at the source; using technological processes at which sound pressure levels at workplaces do not exceed permissible; using remote control of noisy machines; automation of control of noisy machines; use of soundproof enclosures, semi-housings, cabins; the device of interlocking systems that turn off the generators of the ultrasound source in case of violation of sound insulation, etc.); construction and acoustic measures; the use of personal protective equipment; organizational measures (the choice of a rational regime of work and rest, reduction of the time spent in noisy conditions, treatment-and-prophylactic and other measures).

Areas with sound levels above 85 dB must be marked with safety signs. The administration is obliged to provide those working in these zones with personal protective equipment. Even a short stay in areas with octave sound pressure levels exceeding 135 dB in any octave band is prohibited.

At enterprises, organizations and institutions, control of noise levels at workplaces should be ensured and rules for safe work in noisy conditions should be established.

Constructive and planning solutions for noise control. It is possible to reduce the noise in the source by increasing the accuracy of manufacturing individual machine units, reducing gaps, improving the static and dynamic balancing of moving parts, replacing sonorous materials with less sonorous ones (steel gears with plastic ones), and installing noise suppressors. Silencers are divided into active - absorbing sound energy received into them and reactive - reflecting energy back to the source.

Intense noise caused by vibration can be reduced by covering the vibrating surface with a material with high internal friction (rubber, asbestos, bitumen), and some of the sound energy is absorbed. The more tightly the material adheres to the vibrating surface, the greater the absorption effect.

Sound absorption is due to the transition of vibrational energy into heat due to friction in the sound absorber. Materials with good sound-absorbing properties are relatively light, porous (mineral felt, glass wool, foam rubber). In small rooms, walls are lined with sound-absorbing materials. In large rooms (over 300 m), the cladding is ineffective, and in them noise reduction is achieved using sound-absorbing screens (flat and volumetric). The screens are placed near noise sources, and the noise reduction in this case reaches 7-8 dB.

Soundproofing is a method of reducing noise by creating structures that prevent the propagation of noise from one insulated room to another. Sound insulating structures are made of dense solid materials (metal, wood, plastics) that well prevent the propagation of noise.

Noisy units can be isolated using soundproofing half-housings, casings, cabins, which should be installed without rigid connections to the equipment. To increase the efficiency of sound insulation, the inner surfaces of the enclosures are lined with sound-absorbing materials.

Reducing the harmful effects of industrial noise on other buildings can be achieved by rational planning of workshops and the placement of green spaces on the territory of the enterprise.

Reduction of noise by construction and acoustic measures. The main construction and acoustic measures to reduce sound pressure levels in workshops include:

installation of equipment that produces noise at lower levels;

installation of equipment and machines in a separate room with increased sound insulation of structures and the minimum dimensions of the required technological openings;

installation of soundproof half-housings, enclosures and cabins of closed and semi-open types for the operator (Figure 1), as well as soundproof shelters for auxiliary personnel, cabins for rest and remote control;

installation of acoustic screens at the most intense noise sources;

device of vibration-absorbing coatings; installation of noise mufflers in heating, ventilation and air conditioning systems, vacuum pumps, compressor plants, separation of the drive equipment into a separate room or its partial isolation with the obligatory installation of sound-absorbing cladding at the area where the drive equipment is located;

installation of mufflers on technological conveyors for feeding wood from a debarking drum to a chipper;

installation of receiving and unloading funnels for a chipper made of metals with a damping layer.

Reducing noise in industrial premises can be achieved by localizing it near the source with soundproof enclosures, cabins, cameras.

Personal protective equipment against noise. The use of personal protective equipment is advisable in cases where active methods either do not provide the desired acoustic effect or are uneconomical, as well as during the development of the main measures for noise suppression.

Personal protective equipment against noise includes earbuds, headphones, helmets - they can reduce noise by up to 40 dB.

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Characteristics and types of industrial noise

Industrial noise - a set of sounds of varying intensity and frequency, randomly changing over time and causing unpleasant subjective sensations in workers.

Industrial noise is characterized by a spectrum that consists of sound waves of different frequencies. When examining noise, the typically audible range of 16 Hz to 20 kHz is divided into frequency bands and the sound pressure, intensity or sound power assigned to each band is determined.

As a rule, the noise spectrum is characterized by the levels of the named quantities, distributed over octave frequency bands.

The frequency band, the upper limit of which is twice the lower limit, i.e. f 2 = 2 f 1 is called an octave.

For a more detailed study of noise, third-octave frequency bands are sometimes used, for which f 2 = 2 1/3 f 1 = 1.26 f 1.

The octave or third octave band is usually given by the geometric center frequency. There is a standard series of geometric mean frequencies of the octave bands in which the noise spectra are considered (f cg min = 31.5 Hz, f cg max = 8000 Hz).

Table 2 Standard range of geometric mean frequencies

f sg, Hz	f 1, Hz	f 2, Hz
16	11	22
31,5	22	44
63	44	88
125	88	177
250	177	355
500	355	710
1000	710	1420
2000	1420	2840
4000	2840	5680
8000	5680	11360

Noises are distinguished according to the frequency response: low-frequency (f sg< 250); cреднечастотные (250 < f сг ≤ 500); высокочастотные (500 < f сг ≤ 8000).

Industrial noise has different spectral and temporal characteristics that determine the degree of its impact on humans. On these grounds, noises are divided into several types. Above, the characteristic of the noise has already been considered. Table 3 shows the characterization of the noise in terms of production.

Table 3 Classification of noise

Classification method	Noise type	Noise characteristic
By the nature of the noise spectrum	Broadband	Continuous spectrum more than one octave wide
	Tonal	In the spectrum of which there are pronounced discrete tones
By time characteristics	Permanent	Sound level changes by no more than 5 dB during an 8-hour working day
	Fickle: time fluctuating intermittent impulse	Sound level changes by more than 5 dB in an 8 hour work day Sound level continuously changes over time The sound level changes stepwise by no more than 5 dB (A), the duration of the interval is 1 s and more Consist of one or more sound signals, the interval duration is less than 1s

Sources of industrial noise

By the nature of the occurrence, the noises of machines or units are divided into:

→ mechanical;

→ aerodynamic and hydrodynamic;

→ electromagnetic.

A number of industries are dominated by mechanical noise, the main sources of which are gears, impact mechanisms, chain drives, rolling bearings, etc. It is caused by the force effects of unbalanced rotating masses, impacts in the joints of parts, knocks in gaps, movement of materials in pipelines, etc. The mechanical noise spectrum occupies a wide frequency range. The defining factors of mechanical noise are the shape, size and type of construction, the number of revolutions, the mechanical properties of the material, the state of the surfaces of interacting bodies and their lubrication. Impact machines, which include, for example, forging and pressing equipment, are a source of impulse noise, and its level at workplaces, as a rule, exceeds the permissible level. At machine-building enterprises, the highest noise level is generated during the operation of metal and woodworking machines.

Aerodynamic and hydrodynamic noise is

1) noises caused by the periodic release of gas into the atmosphere, the operation of screw pumps and compressors, pneumatic motors, internal combustion engines;

2) noises arising from the formation of flow vortices at solid boundaries. These noises are most typical for fans, turbo blowers, pumps, turbochargers, air ducts;

3) cavitation noise arising in liquids due to the loss of tensile strength by the liquid when the pressure drops below a certain limit and the appearance of cavities and bubbles filled with liquid vapors and gases dissolved in it.

During the operation of various mechanisms, units, equipment, noises of a different nature may occur at the same time.

Any noise source is characterized primarily by sound power. Sound power from a source is the total amount of sound energy emitted by a noise source into the surrounding area.

Since sources of industrial noise, as a rule, emit sounds of different frequencies and intensities, the full noise characteristic of the source is given by the noise spectrum - the distribution of sound power (or sound power level) over octave frequency bands.

Noise sources often emit sound energy unevenly in directions. This irregularity of radiation is characterized by the coefficient Ф (j) - the directivity factor.

The directivity factor Ф (j) shows the ratio of the sound intensity I (j) generated by the source in the direction with the angular coordinate j to the intensity I cf, which would be developed at the same point by an undirected source having the same sound power and radiating sound in all directions evenly :

Ф (j) = I (j) / I avg = p 2 (j) / p 2 av,

where p cf is the sound pressure (averaged over all directions at a constant distance from the source); p (j) is the sound pressure in the angular direction j, measured at the same distance from the source.

Measurement of noise. Sound level meters

All noise measurement methods are divided into standard and non-standard. Standard measurements are governed by the relevant standards and provided by standardized measuring instruments. The quantities to be measured are also standardized. Non-standard methods are used in scientific research and in solving special problems.

Measuring stands, installations, instruments and sound-measuring chambers are subject to metrological certification in the relevant services with the issuance of certification documents, which indicate the main metrological parameters, the limiting values ​​of the measured quantities and the measurement error.

The standard values ​​to be measured for constant noise are: sound pressure level in octave or one-third octave frequency bands at test points; sound level at control points.

Sound measuring devices - sound level meters - usually consist of a sensor (microphone), amplifier, frequency filters (frequency analyzer), a recording device (recorder or tape recorder) and an indicator showing the level of the measured value in dB. Sound level meters are equipped with frequency correction units with switches A, B, C, D and time characteristics with switches F (fast) - fast, S (slow) - slowly, I (pik) - impulse. The F scale is used when measuring constant noise, S - oscillating and intermittent, I - impulse.

In terms of accuracy, sound level meters are divided into four classes 0, 1, 2 and 3. Class 0 sound level meters are used as exemplary measuring instruments; class 1 instruments - for laboratory and field measurements; 2 - for technical measurements; 3 - for approximate measurements. Each class of devices corresponds to a measurement range in terms of frequencies: sound level meters of classes 0 and 1 are designed for the frequency range from 20 Hz to 18 kHz, class 2 - from 20 Hz to 8 kHz, class 3 - from 31.5 Hz to 8 kHz.

To measure the equivalent noise level when averaging over a long period of time, integrating sound level meters are used.

Devices for measuring noise are built on the basis of frequency analyzers, consisting of a set of band-pass filters and instruments showing the sound pressure level in a certain frequency band. Depending on the type of filter frequency characteristics, the analyzers are divided into octave, third-octave and narrowband.

The frequency response of the filter K (f) = U out / U in is the dependence of the signal transmission coefficient from the input of the filter U in to its output U out on the frequency of the signal f.

To measure industrial noise, the VShV-003-M2 device is mainly used, which belongs to the sound level meters of the I accuracy class and allows you to measure the corrected sound level on the A, B, C scales; sound pressure level in the frequency range from 20 Hz to 18 kHz and in octave bands in the range of geometric mean frequencies from 16 to 8 kHz in free and diffuse sound fields. The device is designed to measure noise in industrial premises and residential areas in order to protect health; in the development and quality control of products; in research and testing of machines and mechanisms.

Industrial Noise Protection Methods

According to GOST 12.1.003-83, in the development of technological processes, design, manufacture and operation of machines, industrial buildings and structures, as well as in the organization of workplaces, all necessary measures should be taken to reduce noise affecting a person to values ​​that do not exceed permissible.

Noise protection should be ensured by the development of noise-safe equipment, the use of means and methods of collective protection, including construction and acoustic, the use of personal protective equipment.

Collective protective equipment should be used first. In relation to the source of excitation of noise, collective protection means are divided into means that reduce noise at the source of its occurrence, and means that reduce noise along the path of its propagation from the source to the protected object.

Reducing noise at the source is accomplished by improving the design of the machine or changing the technological process. Means that reduce noise at the source of its origin, depending on the nature of noise generation, are divided into means that reduce noise of mechanical origin, aerodynamic and hydrodynamic origin, and electromagnetic origin.

Methods and means of collective protection, depending on the method of implementation, are subdivided into construction-acoustic, architectural-planning and organizational-technical and include:

→ change in directivity of noise emission;

→ rational planning of enterprises and industrial premises;

→ acoustic treatment of premises;

→ application of sound insulation.

In some cases, the directivity index reaches 10-15 dB, which must be taken into account when using installations with directional radiation, orienting these installations so that the maximum of the radiated noise is directed in the opposite direction from the workplace.

The rational layout of enterprises and industrial premises allows to reduce the noise level at workplaces by increasing the distance to noise sources.

When planning the territory of enterprises, the most noisy premises should be concentrated in one or two places. The distance between noisy and quiet rooms should provide the required noise reduction. If the enterprise is located within the city, then noisy premises should be located in the depths of the territory of the enterprise, as far as possible from residential buildings.

Inside the building, quiet rooms should be located away from noisy ones so that they are separated by several other rooms or a fence with good sound insulation.

Acoustic treatment of a room is the cladding of a part of the internal enclosing surfaces with sound-absorbing materials, as well as the placement of piece absorbers in the room, which are freely suspended volumetric absorbing bodies of various shapes.

Sound absorption is understood as the property of surfaces to reduce the intensity of the waves reflected by them by converting sound energy into heat. The effectiveness of noise reduction by sound absorption depends mainly on the acoustic characteristics of the room itself and the frequency characteristics of the materials used for acoustic treatment. Most often, homogeneous porous materials are used for acoustic treatment, the selection criterion of which is the correspondence of the maximum in the frequency efficiency of the material to the maximum in the spectrum of the reduced noise in the room.

Acoustically treated surfaces of the room reduce the intensity of the reflected sound waves, which leads to a decrease in noise in the area of ​​the reflected sound; in the area of ​​direct sound, the effect of acoustic treatment is much lower.

Sound-absorbing cladding is placed on the ceiling and in the upper parts of the walls (with a room height of no more than 6-8 m) so that the acoustically treated surface makes up at least 60% of the total area of ​​the surfaces limiting the room. In relatively low (less than 6 m) and extended rooms, it is recommended to install the cladding on the ceiling. In narrow and very high rooms, it is advisable to place the cladding on the walls, leaving only their lower parts (2 m in height) unlined. In rooms with a height of more than 6 m, a sound-absorbing suspended ceiling should be provided.

If the area of ​​the surfaces on which the sound-absorbing lining can be placed is small, or it is structurally impossible to perform the lining on the enclosing surfaces, then piece sound absorbers are used.

In the region of medium and high frequencies, the effect of the use of acoustic cladding can be 6-15 dB.

The architectural and planning solutions also include the creation of sanitary protection zones around enterprises. As the distance from the source increases, the noise level decreases. Therefore, the creation of a sanitary protection zone of the required width is the simplest way to ensure sanitary and hygienic standards around enterprises.

The choice of the width of the sanitary protection zone depends on the installed equipment, for example, the width of the sanitary protection zone around large thermal power plants can be several kilometers. For objects located within the city, the creation of such a sanitary protection zone sometimes becomes an insoluble task. The width of the sanitary protection zone can be reduced by reducing noise along the path of its propagation.

Personal protective equipment (PPE) is used if it is not possible to ensure the permissible noise level at the workplace by other means. The principle of PPE is to protect the most sensitive channel of noise impact on the human body - the ear. The use of PPE allows you to prevent the disorder not only of the hearing organs, but also of the nervous system from the action of an excessive irritant.

PPE is most effective, as a rule, in the high frequency region.

PPE includes earplugs, earmuffs, helmets and hard hats, and special suits.



Noise Is a set of sounds that adversely affect the human body and interfere with his work and rest.

The sources of sound are elastic vibrations of material particles and bodies transmitted by liquid, solid and gaseous media.

The speed of sound in air at normal temperature is approximately 340 m / s, in water - 430 m / s, in diamond - 18,000 m / s.

Sound with a frequency from 16 Hz to 20 kHz is called audible, with a frequency of less than 16 Hz - and more than 20 kHz -.

The area of ​​space in which sound waves propagate is called the sound field, which is characterized by the intensity of the sound, the speed of its propagation and the sound pressure.

Sound intensity Is the amount of sound energy transmitted by a sound wave in 1 s through an area of ​​1 m 2 perpendicular to the direction of sound propagation, W / m2.

Sound pressure- it is called the difference between the instantaneous value of the total pressure created by the sound wave and the average pressure that is observed in an undisturbed medium. The unit of measurement is Pa.

The hearing threshold of a young person in the frequency range from 1,000 to 4,000 Hz corresponds to a pressure of 2 × 10-5 Pa. The greatest value of the sound pressure that causes painful sensations is called the pain threshold and is 2 × 102 Pa. Between these values ​​lies the area of ​​auditory perception.

The intensity of human exposure to noise is estimated by the sound pressure level (L), which is defined as the logarithm of the ratio of the effective sound pressure to the threshold. The unit of measurement is decibel, dB.

At the threshold of audibility at an average geometric frequency of 1,000 Hz, the sound pressure level is zero, and at the threshold of pain, it is 120-130 dB.

Noises surrounding a person have different intensities: whispering - 10-20 dBA, colloquial speech - 50-60 dBA, noise from a car engine - 80 dBA, and from a cargo car - 90 dBA, noise from an orchestra - 110-120 dBA, noise during takeoff jet aircraft at a distance of 25 m - 140 dBA, a shot from a rifle - 160 dBA, and from a heavy gun - 170 dBA.

Types of industrial noise

Noise in which sound energy is distributed over the entire spectrum is called broadband; if a sound of a certain frequency is heard, the noise is called tonal; noise perceived as individual impulses (shocks) is called impulse.

Depending on the nature of the spectrum, the noise is divided into low-frequency(the maximum sound pressure is less than 400 Hz), mid-frequency(sound pressure within 400-1000 Hz) and high frequency(sound pressure is more than 1000 Hz).

Depending on the time characteristics, the noises are divided into permanent and fickle.

Intermittent noises are hesitant by time, the sound level of which is continuously changing over time; intermittent, the sound level of which drops sharply to the background noise level; impulse consisting of signals less than 1 s.

Depending on the physical nature, noises can be:

• mechanical - arising from vibration of machine surfaces and during single or periodic shock processes (stamping, riveting, stubbing, etc.);
• aerodynamic- noises of fans, compressors, internal combustion engines, steam and air emissions into the atmosphere;
• electromagnetic - arising in electrical machines and equipment due to the magnetic field caused by electric current;
• hydrodynamic - arising from stationary and non-stationary processes in liquids (pumps).

Depending on the nature of the action, the noises are divided into stable, intermittent and howling; the last two are especially detrimental to hearing.

Noise is created by single or complex sources located outside or inside the building - these are, first of all, vehicles, technical equipment of industrial and household enterprises, ventilators, gas-turbine compressor units, sanitary-technical equipment of residential buildings, transformers.

In the industrial sector, noise is most common in industry and agriculture. A significant level of noise is observed in the mining industry, mechanical engineering, logging and woodworking, and the textile industry.

Effects of noise on the human body

Noise arising from the operation of production equipment and exceeding the standard values ​​affects the central and autonomic nervous system of a person, and the organs of hearing.

Noise is perceived very subjectively. In this case, the specific situation, the state of health, the mood, the environment matter.

Major physiological effects of noise lies in the fact that the inner ear is damaged, changes in the electrical conductivity of the skin, bioelectric activity of the brain, heart and respiration rate, general motor activity, as well as changes in the size of some glands of the endocrine system, blood pressure, narrowing of blood vessels, dilation of the pupils of the eyes are possible. A person working under conditions of prolonged noise exposure experiences irritability, headache, dizziness, memory loss, increased fatigue, decreased appetite, and sleep disturbance. In a noisy background, communication between people deteriorates, as a result of which there is sometimes a feeling of loneliness and dissatisfaction, which can lead to accidents.

Long-term exposure to noise, the level of which exceeds the permissible values, can lead to a person's illness with noise sickness - sensorineural hearing loss. Based on the above, noise should be considered the cause of hearing loss, some nervous disorders, reduced productivity at work and some cases of loss of life.

Hygienic noise regulation

The main goal of standardizing noise at workplaces is to establish the maximum permissible noise level (MPL), which, during daily (except weekends) work, but not more than 40 hours per week during the entire working experience, should not cause diseases or deviations in health detected by modern research methods in the course of work or long-term life span of the present and subsequent generations. Compliance with the remote control for noise does not exclude health problems in hypersensitive persons.

Acceptable noise level- this is a level that does not cause significant concern in a person and significant changes in the indicators of the functional state of systems and analyzers that are sensitive to noise.

The maximum permissible noise levels at workplaces are regulated by SN 2.2.4 / 2.8.562-96 "Noise at workplaces, in premises of residential, public buildings and on the territory of residential buildings", SNiP 23-03-03 "Protection against noise".

Noise protection measures

Noise protection is achieved by the development of noise-safe equipment, the use of collective protection means and methods, as well as personal protective equipment.

Development of noise-safe equipment- reduction of noise at the source - achieved by improving the design of machines, the use of low-noise materials in these structures.

The means and methods of collective protection are subdivided into acoustic, architectural and planning, organizational and technical.

Acoustic noise protection means:

• sound insulation (installation of soundproof cabins, casings, fences, installation of acoustic screens);
• sound absorption (use of sound-absorbing facings, piece absorbers);
• noise mufflers (absorption, reactive, combined).

Architectural planning methods- rational acoustic layout of buildings; placement in buildings of technological equipment, machines and mechanisms; rational placement of workplaces; planning of traffic zones; creation of noise-proof zones in places where a person is located.

Organizational and technical measures- changes in technological processes; remote control and automatic control device; timely scheduled preventive maintenance of equipment; rational mode of work and rest.

If it is impossible to reduce the noise acting on workers to permissible levels, then it is necessary to use personal protective equipment (PPE) - anti-noise earplugs made of ultra-thin fiber “Earplugs” of disposable use, as well as anti-noise earplugs of reusable use (ebonite, rubber, foam) in the form cone, fungus, petal. They are effective in reducing noise at medium and high frequencies by 10-15 dBA. Headphones reduce the sound pressure level by 7-38 dB in the frequency range 125-8000 Hz. To protect against noise exposure with a general level of 120 dB and above, it is recommended to use headsets, headbands, helmets, which reduce the sound pressure level by 30-40 dB in the frequency range 125-8000 Hz.

See also

Industrial noise protection

The main activities to combat noise are technical measures that are carried out in three main areas:

• elimination of the causes of noise or its reduction at the source;
• attenuation of noise along transmission paths;
• direct protection of workers.

The most effective means of reducing noise is replacement of noisy technological operations with low-noise or completely silent, but this way of dealing with noise is not always possible, therefore, it is of great importance to reduce noise at the source - by improving the design or circuit of that part of the equipment that produces noise, using materials with reduced acoustic properties in the design, equipment at the source of additional noise soundproofing device or fence located as close to the source as possible.

One of the simplest technical means of dealing with noise along transmission paths is soundproof enclosure covering a separate noisy part of the machine.

A significant effect of reducing the noise from the equipment is provided by the use of acoustic screens that screen off the noisy mechanism from the workplace or the service area of ​​the machine.

The use of sound-absorbing claddings for finishing the ceiling and walls of noisy rooms (Fig. 1) changes the noise spectrum towards lower frequencies, which, even with a relatively small decrease in the level, significantly improves working conditions.

Rice. 1. Acoustic treatment of premises: a - sound-absorbing facings; b - piece sound absorbers; 1 - a protective perforated layer; 2 - sound-absorbing material; 3 - protective fiberglass; 4 - wall or ceiling; 5 - air gap; 6 - a plate made of sound-absorbing material

To reduce aerodynamic noise, use mufflers, which are usually divided into absorption ones, using the lining of the surfaces of the air ducts with sound-absorbing material: reactive types of expansion chambers, resonators, narrow branches, the length of which is equal to 1/4 of the wavelength of the damped sound: combined, in which the surfaces of the reactive mufflers are lined with sound-absorbing material; screen.

Considering that at present it is not always possible to solve the problem of noise reduction with the help of technical means, great attention should be paid to the use of personal protective equipment: headphones, earbuds, helmets that protect the ear from the harmful effects of noise. The effectiveness of personal protective equipment can be ensured by their correct selection depending on the levels and spectrum of noise, as well as by monitoring the conditions of their operation.

Introduction

1. Noise. Its physical and frequency response. Noise sickness.

1.1 The concept of noise.

1.2 Noise levels. Basic concepts.

1.3. Noise disease - pathogenesis and clinical manifestations

1.4. Limitation and regulation of noise.

2. Industrial noise. Its types and sources. Main characteristics.

2.1 Characteristics of noise in production.

2.2 Sources of occupational noise.

2.3 Measurement of noise. Sound level meters

2.4 Methods of protection against noise in enterprises.

3. Household noise.

3.1 Problems of Household Noise Reduction

3.2 Noise of road transport

3.3 Railway noise

3.4 Reducing exposure to aircraft noise

Conclusion

List of used literature

INTRODUCTION

The twentieth century has become not only the most revolutionary in terms of the development of technology and technology, but also became the noisiest in all of human history. It is impossible to find an area of ​​life of a modern person, where there would be no noise - as a mixture of sounds annoying or disturbing a person.

The problem of "noise invasion" in the modern world is recognized in almost all developed countries. If in a little over 20 years the noise level has grown from 80 dB to 100 dB on city streets, then it can be assumed that within the next 20-30 years, the noise pressure level will reach critical limits. This is why serious measures are being taken around the world to reduce sound pollution levels. In our country, issues of sound pollution and measures to prevent it are regulated at the state level.

Noise can be any kind of sound vibration that at a given moment in time causes emotional or physical discomfort in this particular individual.

When reading this definition, a kind of "discomfort of perception" may arise - that is, a state in which the length of the phrase, the number of turns and the expressions used make the reader frown. Conventionally, the state of discomfort caused by sound can be characterized by the same symptoms. If the sound causes these symptoms, we are talking about noise. It is clear that the above method of identifying noise is to a certain extent conventional and primitive, but, nevertheless, it does not cease to be correct. Below we will consider the problematics of the issue of noise pollution and outline the main directions in which work is being carried out to combat them.

1. Noise. Its physical and frequency response. Noise sickness.

1.1 What is noise

Noise is a combination of sounds of different strength and frequency, which can have an effect on the body. From a physical point of view, a noise source is any process as a result of which there is a change in pressure or fluctuations in physical media. In industrial enterprises, there can be a great variety of such sources, depending on the complexity of the production process and the equipment used in it. Noise is created by all, without exception, mechanisms and assemblies that have moving parts, a tool, in the process of its use (including a primitive hand tool). In addition to industrial noise, in recent years, household noise has begun to play an increasingly significant role, a significant part of which is traffic noise.

1.2 Noise levels. Basic concepts.

The main physical characteristics of sound (noise) are frequency, expressed in hertz (Hz) and sound pressure level, measured in decibels (dB). Range from 16 to 20,000 vibrations per second (Hz), the human hearing aid is able to perceive and interpret. Table 1 lists approximate noise levels and their corresponding characteristics and sound sources.

Table 1. Scale of noise (sound levels, decibels).

Decibel, dB	Characteristic	Sound sources
0	I can not hear anything
5	Almost inaudible	quiet rustle of leaves
10
15	Barely audible	rustle of foliage
20		whisper of a person (at a distance of less than 1m).
25	Quiet	human whisper (more than 1m)
30		the whisper, the ticking of the wall clock. The norm for living quarters at night, from 23 to 7 o'clock.
35	Quite audible	muffled conversation
40		ordinary speech. The norm for residential premises, from 7 to 23 hours.
45		normal conversation
50	Clearly audible	conversation, typewriter
55		Standard for Class A offices
60	Noisy	Norm for offices (offices)
65		loud talk (1m)
70		loud conversations (1m)
75		scream, laugh (1m)
80-95	Very noisy	Scream / muffled motorcycle / freight rail car (seven meters) subway car (7m)
100-115	Extremely noisy	orchestra, subway car (intermittently), thunderclaps. The maximum permissible sound pressure for the headphones.
		in an airplane (until the 80s of the twentieth century)
		helicopter
		sandblasting machine
120	Almost unbearable	jackhammer distance less than 1m.
125
130	Pain threshold	the plane at the start
135-145	Contusion	jet airplane taking off / rocket launch
150-155	Contusion, trauma
160	Shock, trauma	shock wave from a supersonic aircraft

1.3 Disease caused by noise - pathogenesis and clinical manifestations

Since the effect of noise on the human body has been studied relatively recently, scientists do not have an absolute understanding of the mechanism of the effect of noise on the human body. Nevertheless, if we talk about the effect of noise, the state of the hearing organ is most often studied. It is the human hearing aid that perceives sound, and accordingly, the hearing aid responds first to extreme sound effects. In addition to hearing organs, a person can perceive sound through the skin (vibration sensitivity receptors). It is known that hearing-impaired people are able to not only sense sound through touch, but also evaluate sound signals.

The ability to perceive sound through the vibration sensitivity of the skin is a kind of functional atavism. The fact is that in the early stages of the development of the human body, the function of the organ of hearing was performed by the skin. In the process of development, the organ of hearing has evolved and became more complex. As its complexity grew, so did its vulnerability. Noise impact injures the peripheral part of the auditory system - the so-called "inner ear". It is there that the primary lesion of the hearing aid is localized. According to some scientists, overvoltage and, as a result, depletion of the apparatus receiving sound plays a primary role in the effect of noise on hearing. Experts - audiologists consider long-term exposure to noise to be a cause that leads to a violation of the blood supply to the inner ear and is the cause of changes and degenerative processes in the hearing organ, including cell degeneration.

There is a term “occupational deafness”. It refers to people in those professions in which excessive noise exposure is more or less permanent. In the course of long-term observations of such patients, it was possible to record changes not only in the organs of hearing, but also at the level of blood biochemistry, which were the result of excessive noise exposure. The group of the most dangerous effects of noise should include difficultly diagnosed changes in the nervous system of a person exposed to regular noise exposure. Changes in the functioning of the nervous system are due to the close connections of the hearing aid with its various departments. In turn, dysfunction in the nervous system leads to dysfunction of various organs and systems of the body. In this regard, it is impossible not to recall the common expression that "all diseases are from the nerves." In the context of the problems under consideration, the following version of this phrase "all diseases from noise" can be proposed.

Primary changes in auditory perception are easily reversible if the hearing is not subjected to extreme stress. However, over time, with constant negative wobbling, changes can become persistent and or irreversible. In this regard, the duration of the effect of sound on the body should be monitored, and in view of the fact that the primary manifestations of "occupational deafness" can be diagnosed in persons working in conditions of noise for about 5 years. Further, the risk of hearing loss among workers increases.

To assess the state of hearing in persons working under conditions of exposure to noise, four degrees of hearing loss are distinguished, presented in Table 2.

Table 2. Criteria for assessing the auditory function for persons working in conditions of noise and vibration (developed by VE Ostapovich and NI Ponomareva).

It is important to understand that the above does not apply to extreme sound effects (see table 1). Exposure to short-term and intense exposure to the hearing organ can lead to complete hearing loss due to destruction of the hearing aid. The result of this injury is complete hearing loss. This effect of sound occurs during a strong explosion, major accident, etc.

The study of industrial noise has shown that, according to the nature of its sound, it is usually subdivided into continuous and broadband. The most significant levels are observed at frequencies of 500-1000 Hz, i.e. in the zone of greatest sensitivity of the hearing organ. This indicates the need for measures to normalize the acoustic regime in the areas where these facilities are located. A large number of different types of technological equipment are installed in production workshops. The noise generated by enterprises largely depends on the effectiveness of noise suppression measures. So, even large ventilation units, compressor stations, various motor test stands can be equipped with noise suppressing devices of various efficiency. Enterprises can have external fences with different sound insulation, which affects the intensity of the noise that spreads to the surrounding area.

The effect of noise on the physiological processes of the human body.

The impact of noise on a person occurs in two directions:

• 1) load on the organ of hearing as a system that perceives sound energy;
• 2) the impact on the central links of the sound analyzer as a system for receiving information.

The load on the organ of hearing is assessed by determining the shift in the thresholds of perception of tones, which depends on the duration of exposure and the magnitude of sound pressure.

The effect on the central nervous system is called "nonspecific" influence, which can be objectively assessed by physiological parameters.

Changes in the functional state of the nervous system under the influence of noise:

• weakness;
• dull headache;
• feeling of heaviness and noise in the head, arising at the end of a work shift or after work;
• dizziness when changing body position;
• decreased ability to work, attention;
• increased sweating, especially with excitement;
• violation of the rhythm of sleep (drowsiness during the day, disturbed sleep at night);
• apathy;
• weakening of memory, unstable mood;
• chilliness;
• increased irritability;
• fast fatiguability;
• increased heart rate.

These symptoms often occur in the absence of pronounced signs of hearing impairment and can be the initial manifestation of any mental illness, and are also observed in neuroses and psychopathies.

The reaction of the cardiovascular system to noise:

• bradycardia (decreased heart rate);
• sinus arrhythmia;
• conduction disturbances;
• reduction in the number of red blood cells in the blood;
• spasm of arterial vessels;
• discomfort in the region of the heart in the form of tingling sensations, palpitations;
• decrease in the capacity of the functioning vascular bed;
• severe instability of pulse and blood pressure, especially during the period of stay in noise.

In addition, there is experimental evidence that certain chemicals affect the nervous system and cause a shift in the hearing threshold in experimental animals, especially if they are used against a background of noise. Such materials include:

• heavy metals such as compounds of lead and trimethyltin;
• organic solvents such as toluene, xylene and carbon disulfide;
• asphyxiant gas - carbon monoxide.

Many of them are found in urban vehicle exhaust.

Changes in the nervous and cardiovascular systems are a nonspecific response of the body to the effects of many stimuli, including noise. Their frequency and severity largely depend on the presence of other concomitant factors. For example, when intense noise is combined with neuro-emotional stress, people often have a tendency to vascular hypertension, and there is also a tendency to an increase in the frequency of diseases such as vegetative-vascular dystonia (by 20%), ischemic heart disease and hypertension. (by 10%), etc.

The effect of noise on the metabolism in the nervous tissue. There have been many studies to investigate the mechanisms of noise-induced disturbances. Important studies on the non-nonspecificity of noise stimulation for cellular formations of the sound analyzer and other structures, for example, spinal ganglia, show that noise can act both directly on the cell and indirectly through the nervous system on it and cause various reactions (denaturation of native proteins, changes in reactivity ), leading to reversible or irreversible changes in cells, which underlies functional damage to organs and systems.

When studying the energy metabolism of animals using biochemical, morphological and electron-microscopic methods, it was found that with prolonged exposure to noise, the adverse effect increases not only from the noise level, but also from its frequency nature.

High-frequency noises (octave band 4000 Hz) in comparison with energy-equivalent low-frequency noises (octave band 125 Hz) cause deeper disturbances in nervous trophism, i.e. processes in neurons that ensure the normal vital activity of the structures (organs and tissues) innervated by them. In addition, the synthesis of high-energy phosphorus compounds is disrupted, high-energy compounds, the molecules of which contain energy-rich, or high-energy, bonds.

An experiment was conducted to study the brains of rats that were exposed to chronic (three months exposure but six hours daily) exposure to intense noise (97 dB). The results of electron microscopic examination of the brain of animals show significant changes in ul trastructures mitochondria and synaptic vesicles of nerve cells, which indicates a violation of the functionality of the synapse. Changes in the structure of mitochondria, as well as clearing of the cytoplasm and uneven distribution of chromatin in the nucleus, indicated the inhibition of oxidative processes and a slowdown in tissue metabolism. These changes in brain cells are consistent with the data of biochemical studies, indicating a violation of trophism and metabolism.

Sleep disturbances under the influence of noise. Intermittent, sudden noises, especially in the evening and at night, have an extremely unfavorable effect on a person who has just fallen asleep. This is due to the fact that during the period of falling asleep, the brain is in a state of "hypnoid" phase. At this time, paradoxical attitudes towards the surrounding reality develop, therefore even weak noise stimuli can produce a disproportionately super-strong effect. Noise that suddenly occurs during sleep (the rumbling of a truck, loud music, etc.) often causes severe fright, especially in patients and children.

Noise decreases the length and depth of sleep. It was found that the chronological configuration of noises, the alternation of noises of varying intensity, plays an important role. So, uneven traffic disturbs sleep more than intense, but uniform. Obviously, adaptation to regular and frequent noises is much easier than to irregular and infrequent ones.

The response to noise exposure depends on the person's age, gender and health status. With the same noise intensity, people aged 70 wake up in 72% of cases, and children 7-8 years old - only in 1% of cases. The threshold noise intensity that causes the awakening of children is 50 dB (A), adults - 30 dB (A), and the elderly react even less. Women wake up more easily with noise. This is because they are more likely than men to transition from deep sleep to light sleep.

Noise affects various stages of sleep. So, the stage of paradoxical sleep, characterized by dreams, rapid eye movements and other signs, should occupy at least 20% of the entire sleep period; a decrease in this stage of sleep leads to serious disorders of the nervous system and mental activity of a person. The shortening of the deep sleep stage leads to hormonal imbalances, depression and other mental disorders.

Under the influence of noise of 50 dB (A), the period of falling asleep increases by an hour or more, sleep becomes superficial, after waking people feel tired, headache, and often palpitations.

The lack of normal rest after a hard day leads to the fact that fatigue that naturally develops after work does not disappear, but gradually turns into chronic overwork, which contributes to the development of a number of diseases, such as disorders of the central nervous system, hypertension.

The effect of noise on the psyche. Loud sounds irritate the central nervous system, in which the level of adrenaline in the blood rises in the body, breathing and heart rate increase, blood pressure rises, the motility of the gastrointestinal tract is suppressed, the vessels of the peripheral circulatory system are narrowed, and muscle tone decreases. At the level of consciousness, the body is brought into a state of readiness and is ready to resist. The body reflexively reacts to noise as a warning signal. This puts a constant strain on the nervous system and does not allow it to recover sufficiently.

Constant noise increases a person's irritability, increases the level of anxiety and aggressiveness.

Effect of noise on attention and work performance. Each person perceives noise differently. The effect of noise on working capacity largely depends on age, temperament, health status, and environmental conditions.

The most unfavorable for the work process are:

• long-term noise with a loudness of over 90 dB;
• intermittent, unexpected or uncontrollable noise less than 90 dB if high frequencies dominate the noise spectrum.

The ability of noise to distract a person from any activity is directly proportional to the loudness, but depends on the person's mood and on the specific situation. For example, a barely audible sound can be annoying, and the roar of a brass band can bring positive emotions. The sharper the transition from silence to noise, the more unpleasant the sound appears.

The following factors negatively affect the work process:

• noise characteristics;
• job characteristics;
• stages of work that are considered important;
• individual perception.

The disturbing effect of noise is also associated with the information it carries: for example, a mother who has fallen asleep may not react to the thunderclaps outside the window, but the quiet, barely audible cry of the child will wake her up instantly. While at the workplace, a person does not notice noises louder than at home, where, according to studies, a person is not disturbed by noise of about 40-45 dB (L) during the day and 35 dB (L) at night. After a period of habituation, most workers will stop paying attention to noise, but will continue to complain of fatigue, irritability, and insomnia. (Habituation will be more successful if beginners are provided with adequate protective equipment from the beginning, before their hearing begins to deteriorate.)

The effect of noise on labor intensity was studied both in laboratory conditions and in real production conditions. Research results have shown that noise usually has little effect on the performance of repetitive, monotonous work, and in some cases it can even lead to an increase in its intensity if the noise level is characterized as low or moderate.

High noise levels can reduce the intensity of work, especially when it comes to performing a complex operation or several operations at the same time. Intermittent noises are usually more disturbing to operation than persistent noise, especially if the noise occurs unexpectedly and cannot be controlled.

It has been established that during work requiring increased attention, with an increase in the sound level from 70 to 90 dB (A), labor productivity decreases by 20%.

Noise interferes with the following tasks:

• tasks that require concentration, learning or analytical thinking;
• tasks, an integral part of which is conversation (listening comprehension);
• tasks that require significant muscle effort;
• synchronous tasks;
• tasks requiring continuous participation in the execution process;
• tasks for which you need to be vigilant for a long time;
• performing any tasks in which it is necessary to perceive auditory signals;
• tasks that require attention in order to perceive several sound signals at the same time.

Since a person is constantly surrounded by an acoustic environment, absolute silence becomes a damaging factor for the human psyche, negatively affecting his life. After a while, all people who are placed in sound and lightproof rooms develop hallucinations (both sound and visual), with which the brain tries to fill in the missing information.

The body's response to noise is largely dependent on age. So, at the age of up to 27 years, 46.3% of people react to noise, and at the age of 58 and older - 72%. A large number of complaints in the elderly is obviously associated with age characteristics and the state of the central nervous system of this age group of the population.

There is also a correlation between the number of complaints and the nature of the work performed. The disturbing effect of noise affects more people who are engaged in mental work than those who work physically, which, apparently, is associated with greater fatigue of the nervous system.