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.

Noise consists of individual sounds and has physical characteristics. 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.

Since there are no ways to directly determine the energy of sound oscillations, the pressure produced on the bodies they fall are measured. 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 perception of noise and sound

A person can perceive as a sound of oscillations with a frequency of 16 to 20,000 Hz. With age, the sensitivity of the sound analyzer decreases, and in old age fluctuations with a frequency above 13 000-15,000 Hz do not cause hearing.

Subjectively frequency, its increase is perceived as an increase in tone, sound height. Usually the basic tone is accompanied by a number of additional sounds (overtones) arising from the oscillation of individual parts of the sounding body. The number and strength of the overtones create a specific color, or the timbre, complex sound, so that it is possible to recognize the sounds of musical instruments or voices of people.

To cause an auditory sensation, sounds must have a certain force. 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. So, to feel hardly noticeable increment of sound volume, it is necessary to increase its physical force by 26%. Under the Law of Weber-Fekhner, the feeling increases in proportion to the not the power of irritation, but the logarithm of his strength.

The sounds of different frequencies at the same physical intensity are felt by the ear not as equally loud. High-frequency sounds are felt like loudest than low-frequency.

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, the force (10-9 erg / cm2 × s s) was conditionally adopted, or 2 × 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 bel. corresponds to a change in the power of the sound 10 times. An increase in the sound of the sound 100 times on the logarithmic scale is indicated as an increase in the level of sound of the sound into 2 bees. The increment of the level of sound of the sound at 3 Bela corresponds to an increase in the absolute force of it in 1000 times and so on.

Thus, to determine the level of force of any sound or noise in Bles, it is necessary to divide its absolute power for the power of the sound, adopted for the level of comparison, and calculate the decimal logarithm of this relationship.

where I1 is absolute force;

I - the power of the sound level of the comparison.

If you express a huge range of sound strength with a frequency of 1000 Hz from the threshold of hears and (zero level) to a painful threshold, then the entire range on the logarithmic scale will be 14 white.

Due to the fact that the hearing body is able to distinguish the growth of sound at 0.1 white, then in practice, a decibel (dB) is used in measuring sounds, i.e., a unit is 10 times less than Bel.

Due to the peculiarity of the perception of the auditory analyzer, the sound of the same volume will be perceived by a person from noise sources with various physical parameters. So, the sound by 50 dB and the 100 Hz frequency will be perceived as equally loud with sound with a power of 20 dB and a frequency of 1000 Hz.

In order to be able to compare the different strength of various strength on the frequency composition of the frequency composition in terms of their volume, a special volume of volume is introduced, called "background". At the same time, the comparison unit adopted a 1000 Hz sound, which is considered standard. In our example, the sound of 50 dB and a frequency of 100 Hz will be 20 backgrounds, since it corresponds to the sound with a force of 20 dB and a frequency of 1000 Hz.

The noise level that does not cause harmful effects for the ear working, or the so-called normal volume limit at a frequency of 1000 Hz, corresponds to 75-80 backgrounds. When increasing the frequency of oscillations of sound compared with the standard volume limit should be reduced, since the harmful effect on the hearing body increases with an increase in the frequency of oscillations.

If the tones constituting the noise are continuously in a wide frequency range, then such noise is called continuous, or solid. If the power of sounds constituting the noise is approximately the same, such noise is called white by analogy with the "white light" characterized by a solid spectrum.

The definition and rationing of noise is usually carried out in the frequency band, equal to octave, half-circuit or a third of the octave. For octave, the frequency range is taken, in which the upper limit of the frequency is twice the lower (for example, 40-80, 80-160, etc.). An octave is usually indicated not to indicate the frequency range, but so-called medium meterometric frequencies. So, for octave 40-80 Hz, a medium meterometric frequency is 62 Hz, for octave 80-160 Hz - 125 Hz, etc.

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

Class 1.Low-frequency (noise noise aggregates of unaware action, noise penetrating through soundproofing obstacles). The greatest levels in the spectrum are located below the frequency of 300 Hz, followed by a decrease (at least 5 dB per octave).

Class 2.Medium-grade noises (the noise of most machines, machine tools and units of the unaware action). The highest levels in the spectrum are located below the frequency of 800 Hz, and further a decrease in no less than 5 dB per octave.

Class 3.High-frequency noise (ringing, hissing, whistling noise, characteristic of shock-action units, air and gas flows, aggregates acting with high speeds). The smallest noise level in the spectrum is located above 800 Hz.

There are noises:

2) Tonal when the noise intensity in the narrow frequency range prevails over the other frequencies.

On the distribution of sound energy in time noise are divided:

1) constant, the sound level of which for an 8-hour working day changes in time for no more than 5 dB;

2) non-permanent, the sound level of which for 8-hour working days is changed by more than 5 dB.

Non-permanent noises are divided into:

1) fluctuated in time, the sound level of which is continuously variable in time;

2) intermittent, the sound level of which stepwise change (by 5 dB or more), and the duration of the intervals with a constant level is 1 s or more;

3) Pulse, consisting of one or more signals with a duration of less than 1 s each, while the sound level changes at least 7 dB.

If, after exposing the noise of one or another tone, the sensitivity to it decreases (the threshold of perception increases) by no more than 10-15 dB, and its restoration occurs no more than 2-3 minutes, it should be thought of adaptation. If the change in the thresholds is significantly, and the recovery duration is delayed, this indicates the occurrence of fatigue. Main form professional pathologycaused by intense noise is a resistant decrease in sensitivity to various colors and whisper speech (professional touginess and deafness).

The effect of noise on the body

The whole complex of disorders, developing in the body under the action of noise, can be combined into the so-called noise disease (prof. E. C. Andreeva-Galanina). Noise disease is the total disease of the whole organism, developing as a result of the impact of noise, with a preferably defeat of the central nervous system and auditory analyzer. The characteristic feature of the noise disease is that the changes in the body proceed by the type of asthenovethative and asthenonevrotic syndromes, the development of which is significantly ahead of violations arising from the auditory function. Clinical manifestations In the body, under the influence of noise, they are divided into specific changes in the hearing organ and nonspecific - in other organs and systems.

Noise Regulation

Noise regulation is carried out taking into account its nature and working conditions, goals and appointments of premises accompanying harmful production factors. For the hygienic assessment of noise, materials are used: CH 2.2.4 / 2.1.8.5622-96 "Noise at workplaces, in premises of residential, public buildings and in residential buildings."

For constant noise, the rationing is produced in octave bands with medium meterometric frequencies 31.5; 63; 125; 250; 500; 1000; 2000; 4000; 8000 Hz. For an indicative assessment, it is allowed to measure the advantage of measuring noise into the dBA in the dBA is that it allows to determine excess permissible levels Noise without spectral analysis of it in octave bands.

At frequencies 31.5 and 8000 Hz, noise is normalized at the level of 86 and 38 dB, respectively. Equivalent sound level in dB (A) is 50 dB. For tonal and impulse noise, it is 5 dB less.

For fluctuating in time and intermittent noise, the maximum sound level should not exceed 110 dB, and for pulsed noise, the maximum sound level of more than 125 dB.

In certain sectors of production in relation to profession, the rationing is carried out taking into account the category of gravity and tension. At the same time, 4 degrees of gravity and tension are distinguished, given the ergonomic criteria:

1) dynamic and static muscle load;

2) nervous load - attention voltage, density of signals or messages for 1 hour, emotional stress, replacement;

3) The voltage of the analyzer function is the vision, the amount of RAM, i.e. the number of elements to be memorized for 2 h or more, intellectual voltage, monotony of work.

At low tension, as well as easy and middle severity Large Noise is regulated at 80 dB. With the same tension (small), but with a severe and very heavy form of labor, it is 5 dB less. With moderately intense labor, intense and very tense, the noise is normalized by 10 dB less, that is, 70, 60 and 50 dB.

The degree of hearing loss is set by the loss of hearing in speech frequencies, i.e., in frequency of 500, 1000 and 2000 Hz and at a professional frequency of 4000 Hz. At the same time, 3 degrees of reduction of hearing are distinguished:

1) a light decrease - on speech frequencies, the reduction of hearing occurs by 10-20 dB, and on professional - by 60 ± 20 dB;

2) a moderate decrease - on speech frequencies, a decrease in hearing at 21-30 dB, and on professional - by 65 ± 20 dB;

3) a significant decrease - according to 31 dB and more, and at professional frequencies by 70 ± 20 dB.

If the familiar sounds suddenly disappear from the environment, then a person will experience significant inconvenience, excitement and even a sense of unfortunate fear: after all, people are born and live in the world of sounds. It should not be forgotten that civilization reached a high level of development due to the ability to communicate in the form of speech - one of the types of communication with sounds. Nevertheless, noise is one of the main adverse production factors. Because of the noise, there are more rapid fatigue, which leads to a decrease in performance by 10 ... 15%, an increase in the number of errors when performing the operations of the employment process and, therefore, to the increased risk of injury. With long-term effects of noise, the sensitivity of the hearing aid, pathological changes in the nervous and cardiovascular systems occur.

Noise is a combination of sounds of various strength and frequency (height), randomly changing in time. By nature, sounds are mechanical oscillations of solids, gases and liquids in the audible frequency range (16 ... 20 000 Hz). In the air, the sound wave propagates from the source of mechanical oscillations in the form of zones of thickening and vacuum. Mechanical oscillations are characterized by amplitude and frequency.

The amplitude of oscillations determines the pressure and power of the sound: how it is more, the greater the sound pressure and louder the sound. The essence of the auditory perception consists in catching the ear of deviation of air pressure generated by the sound wave, from atmospheric. The value of the lower absolute threshold sensitivity of the auditory analyzer is 2-10 ~ 5pa at a frequency of 1000 Hz, and the upper threshold is 200 Pa at the same sound frequency.

The frequency of oscillation affects the auditory perception and determining! Height of sound. The fluctuations with a frequency below 16 Hz make up an infrasound area, and above 20,000 Hz - ultrasounds. With age (about 20 years old), the upper boundary of the person perceived frequencies is reduced: in middle-aged people up to 13 ... 15 kHz, elderly - up to 10 kHz and less. The sensitivity of the hearing aid with increasing frequency from 16 to 1000 Hz rises, at frequencies of 1000 ... 4000 Hz it is maximum, and at a frequency of more than 4000 Hz drops.

The physiological feature of the perception of the frequency composition of the sounds is that the person's ear reacts not to absolute, but to the relative frequency growth: an increase in the frequency of oscillations is half perceived as an increase in the height of the sound to a certain value called an octava. Therefore, the octave is made called the frequency range in which the upper boundary is twice as much longer. The audible frequency range is divided into octaves with medium geometric frequencies 31.5; 63; 125; 250; 500; 1000; 2000; 4000; 8000 and 16000 Hz. Medium geometric frequencies occupy an intermediate position in octave. They are determined from the expression

where FN and FB are the bottom and upper frequency value in the octave.

In the hygienic estimate of noise, its intensity is measured (strength) and determine the spectral composition at the frequency of sounds of the sounds. The intensity of the sound is the amount of sound energy carried by the sound wave per unit of time and referred to a single surface area perpendicular to the direction of the wave propagation. Sound intensity values \u200b\u200bare changed in very wide range - from 10-12 to 10 W / m2. Due to the strong stretchability of the intensity change range and the peculiarities of the perception of sounds (see the Weber-Fehener law), logarithmic values \u200b\u200bare introduced - the level of intensity and sound pressure level expressed in decibels (dB). When using a logarithmic scale, the audio intensity level:

Li \u003d 101G (I / I0),

sound pressure level:

where I and I0 are respectively the actual and threshold value of the intensity of the sound, W / m2: I0 \u003d 10-12 W / m2 at the reference frequency FE \u003d 1000 Hz; P and P 0 - respectively, the actual and threshold sound pressure, Pa: P0 \u003d 2 * 10-5 Pa at FE \u003d 1000 Hz.

Fig. 19.1. Curves equal volume of sounds

Use the logarithmic scale of sound pressure levels is convenient, since the sounds differ from each other. The sounds are stacked in the range of 130 ... 140 dB. For example, the sound pressure level created during human breathing is within 10 ... 15 dB, whisper - 20 .... 25, normal conversation - 50 ... 60, created by a motorcycle-95 ... 100, engines Reactive aircraft on takeoff - 110 ... 120 dB. However, when comparing various noise, it is necessary to remember that noise with an intensity level of 70 dB is twice as long as noise of 60 dB and four times louder noise with a level of intensity of 50 dB, which follows from the logarithmic scale. In addition, the sounds of the same intensity, but different frequencies are perceived by hearing unenochnakovo, especially at the level of intensity less than 70 dB. The reason for such a phenomenon is greater ear sensitivity to high frequencies.

In this regard, the concept of sound volume, the units of measurement of which serve as backgrounds and sons. Sound volume is determined by comparing them with a reference sound of 1000 Hz. For the reference sound, the unit of its intensity in decibels is equal to the backgrounds (Fig. 19.1). Thus, the volume of sound with a frequency of 1000 Hz and the intensity of 30 dB is equal to 30 backgrounds, the same value is the volume of the sound of 50 dB with a frequency of 100 Hz.

Measuring the volume in the sones shows that how many times one sound is louder than the other. Volume level in 40 background is taken for 1 sleep, in 50 background - for 2 sons, in 60 background - for 4 sons, etc. Consequently, with an increase in volume on 10 backgrounds, its value in sons increases twice.

To ensure the safety of production activities, it is necessary to consider the ability of sound waves to reflect from surfaces or absorb them. The degree of reflection depends on the form of the reflective surface and the properties of the material from which it is made. With a large inner resistance of materials (such as felt, rubber, etc.), the main part of the sound wave falling on them (energy) is not reflected, but is absorbed. Features of the design and shape of the premises can lead to a repeated sound of sound from the surfaces of the floor, walls and ceiling, thereby lengthening the time of the sound. Such a phenomenon is called reverb. The possibility of reverberation is taken into account at the stage of designing buildings and premises, in which noisy machines and equipment are supposed to be installed.

Studies of recent years have shown that among many natural and anthropogenic environmental factors affecting the health of the population, the most common and aggressive is urban noise.

Physical and physiological characteristics of noise. Under the term "noise" understands any unpleasant or unwanted sound or their combination that interfere with the perception of beneficial signals is disturbed by silence, adversely affect the human body, reduce its performance.

Sound as a physical phenomenon is mechanical oscillations of the elastic medium in the audible frequency band. Sound as a physiological phenomenon is a sensation perceived by the hearing organ when exposed to sound waves.

Sound waves always occur if there is a oscillating body in an elastic medium or when particles of an elastic medium (gaseous, liquid or solid) fluctuate due to the impact on any exciting force on them. However, not all oscillatory movements are perceived by the hearing body as a physiological feeling of sound. The human ear can only hear oscillations whose frequency ranges from 16 to 20,000 in 1 seconds. It is measured in Hertz (Hz). The fluctuations with a frequency of up to 16 Hz are called an infrasound, more than 20,000 Hz - ultrasound, and their ear does not perceive. In the future, there will be only a question of audible oscillations heard.

Sounds can be simple, consisting of one sinusoidal oscillation (pure tones), and complex, characterized by oscillations of different frequencies. Sound waves distributed in the air are called air sound. The oscillations of sound frequencies propagating in solids are called sound vibration, or structural sound.

A part of the space in which sound waves apply is called the sound field. The physical state of the medium in the sound field, or, more precisely, the change in this state (the presence of waves) is characterized by sound pressure (P). This is an excessive alternating pressure resulting from an atmospheric in an environment where sound waves pass. Measure it in Newton per square meter (N / m2) or in Pascal (PA).

Sound waves arising in the medium are distributed from the point of their appearance - the sound source. A certain period of time is needed so that the sound reaches another point. The speed of sound propagation depends on the nature of the medium and the type of sound wave. In the air at a temperature of 20 ° C and normal atmospheric pressure, the speed of the sound is 340 m / s. Sound speed (C) should not be mixed with a vibrational velocity of the particles (V) of the medium, which is a signage of the magnitude and depending on both the frequency and the magnitude of the sound pressure.

The length of the sound wave (K) is called the distance to which the oscillatory movement is distributed in the medium in one period. In isotropic environments, it depends on the frequency (/) and the sound speed (C), namely:

The oscillation frequency determines the height of the sound. The total amount of energy that is emitted by the source of the sound into the environment per unit of time, characterizes the flow of sound energy, is determined in wats (W). Practical interest is not the entire flow of sound energy, but only that part of it that reaches the ear or the microphone diaphragm. Part of the flow of sound energy, which falls on a unit area, is called the intensity (strength) of the sound, it is measured in watts per 1 m2. The intensity of the sound is directly proportional to sound pressure and vibrational speed.

Sound pressure and intensity of sound are changed in a large range. But the human ear captures fast and minor pressure changes within certain limits. There are upper and lower limits of the hearing sensitivity of the ear. The minimum sound energy that generates the feeling of sound is called the hearing threshold, or the threshold of perception, for the standard sound (tone) of 1000 Hz and intensity 10 ~ 12 W / m2. The sound pressure is 2 Yu-5 Pa. The sound wave of large amplitude and energy has a traumatic effect, determines the appearance of unpleasant sensations and pain in the ears. This is the upper limit of the hearing sensitivity - the threshold of the pain. It corresponds to the sound with a frequency of 1000 Hz with its intensity of 102 W / m2 and sound pressure of 2 102 Pa (Fig. 101).

Fig. 101. Range of sensitivity thresholds by A. Bella

The ability of the auditory analyzer to perceive the large range of sound pressure is due to the fact that it catches the difference, but the multiplicity of changes in absolute values \u200b\u200bcharacterizing the sound. Therefore, measure the intensity and sound pressure in absolute (physical) units is supervised and inconvenient.

In acoustics to characterize the intensity of sounds, or noise, use a special measuring system, where almost logarithmic dependence between irritation and auditory perception is taken into account. This is a white scale (b) and decibel (dB), which meets the physiological perception and gives the opportunity to sharply reduce the range of values \u200b\u200bof the measured values. On this scale, each subsequent stage of sound energy is greater than the previous 10 times. For example, if the intensity of the sound is greater than 10, 100, 1000 times, then on the logarithmic scale it corresponds to an increase of 1, 2, 3 units. The logarithmic unit that reflects a ten-fold degree of increasing the intensity of sound above the sensitivity threshold is called white, i.e. it is a decimal logarithm of the intensity of sounds.

Therefore, to measure the intensity of sounds in hygienic practice, not absolute the values \u200b\u200bof sound energy or pressure, but relative, which express the energy ratio or pressure of this sound to the hearing thresholds of energy or pressure, are used. The energy range that is perceived by the ear as a sound is 13-14 B. For convenience, not white, but a unit, which is 10 times less, is a decibel. These values \u200b\u200bare called sound intensity levels or sound pressure.

Since the intensity of the sound is proportional to the square of the sound pressure, it can be determined by the formula:

Where P is the audible pressure (PA); P0 is the threshold value of the sound pressure (2 10 "5 pa). Consequently, the highest level of sound pressure (pain threshold) will be:

After standardizing the p0 threshold value, the sound pressure levels determined relative to it became absolute, as they definitely correspond to the sound pressure values.

Sound pressure levels in different places and during operation of various noise sources are shown in Table. 90.

Table 90 Sound Pressure Sources Noise, DB

Sound energy emitted by the source of noise is distributed in frequencies. Therefore, it is necessary to know how the level of sound pressure is distributed, i.e. the frequency spectrum of radiation.

Currently, hygienic rationing is carried out in the sound frequency range from 45 to 11 200 Hz. In tab. 91 shows the most commonly used row of eight octave bands.

Table 91 Main series of octave bands

Often you have to fold the levels of sound pressure (sound) of two or more noise sources or find them average. Addition is carried out using Table. 92.

Table 92 Addition of sound pressure or sound level

Produce a sequential addition of sound pressure levels, starting with the maximum. First determine the difference between the two components of the sound pressure levels, after which they are found by the difference as defined using the table, are found. It is added to the greater of the components of sound pressure levels. Similar actions produced with a certain amount of two levels and third level, etc.

Example. Suppose that it is necessary to add sound pressure levels L [- 76 dB UL2 \u003d 72 dB. Their difference is: 76 dB - 72 dB \u003d 4 dB. Table. 92 Find amendment on the difference of 4 dB levels: i.e. al \u003d 1.5. Then the total level of LSUM \u003d b6ol + Al \u003d 76 + 1.5 \u003d 77.5 dB.

Most noise contains the sounds of almost all the frequencies of the auditory range, but is distinguished by different distribution of sound pressure levels in frequencies and their change in time. Classify noise acting on a person, according to their spectral and temporal characteristics.

According to the nature of the spectrum of noise, they are separated into broadband with a continuous spectrum of more than one octave width and tonal, in the spectrum of which there are audible discrete tones.

In appearance, the noise spectrum can be low-frequency (with a maximum of sound pressure in the frequency range of less than 400 Hz), mid-frequency (with a maximum of sound pressure in the frequency range of 400-1000 Hz) and high-frequency (with a maximum sound pressure on the frequency portion over 1000 Hz). In the presence of all frequencies, the noise is conventionally called white.

According to the time characteristic, noise is divided into permanent (the sound level changes no more than 5 dBA) and non-permanent (the sound level changes over time for more than 5 dBA).

The noise of permanent pumping or ventilation plants, equipment of industrial enterprises (blowers, compressor installations, various test stands can be permanent.

Non-permanent noises, in turn, are divided into oscillatory (sound level changes all the time), intermittent (the sound level drops sharply to the background several times over the observation period, and the duration of the intervals during which the noise level remains constant and exceeds the background, is 1 s or more) and impulse (consisting of one or more consecutive blows duration up to 1 seconds), rhythmic and neurotic.

The noise of transport belongs to the non-permanent. Intermittent noise is noise from the work of the elevator winch, periodically enabled refrigerator aggregates, some installations of industrial enterprises or workshops.

The impulse can be attributed to noises from a pneumatic hammer, grasshuscular press equipment, flaking by the doors, etc.

In terms of sound pressure, the noise is divided into low, medium power, strong and very strong.

Noise estimation methods depend primarily on the nature of noise. Permanent noise is estimated at sound pressure levels (L) in decibels in octave stripes with medium-meter frequencies 63, 125, 250, 500, 1000, 2000, 4000 and 8000 Hz. This is the main method of evaluating noise.

To evaluate non-permanent noise, as well as an indicative estimate of constant noise, the term "sound level" is used, i.e. general level Sound pressure, which determine the sound leisure at the frequency correction A, characterizing the frequency indicators of the noise perception of the human ear1.

The relative frequency response of the correction and the noiseomer is given in Table. 93.

Table 93 Relative frequency response Correction A

Correction curve A corresponds to a curve equal to volume with a sound pressure level of 40 dB at a frequency of 1000 Hz.

Non-permanent noises are approved by equivalent sound levels.

Equivalent (Energy) The sound level (La eq, dBA) of a certain non-permanent noise is the level of sound of a constant broadband non-violent noise, which has the same rms sound pressure as this non-permanent noise for a certain time.

Sources of noise and their characteristics. The noise level in the apartments depends on the location of the house relative to sources of noise, the internal planning of the premises of various purposes, sound insulation of the building structures, equipping it with engineering and technological and sanitary equipment.

Sources of noise in the environment The medium can be divided into two large groups - internal and external. The internal sources of noise, first of all, include engineering, technological, domestic and sanitary equipment, as well as noise sources directly related to people's vital activity. External sources of noise are various means of transport (ground, water, air), industrial and energy enterprises and institutions, as well as various noise sources inside the quarters associated with people's vital activity (for example, sports and playgrounds, etc.).

Engineering and sanitary equipment - elevators, water pumping pumps, garbage chute, ventilation plants, etc. (more than 30 types of modern buildings) - sometimes create noise in apartments up to 45-60 dBA.

Sources of noise are also musical instruments, tools and household appliances (air conditioners, vacuum cleaners, refrigerators, etc.).

While walking, dancing, moving the furniture, the runner of children arise sound oscillations, transmitted to the design of overlaps, walls and partitions and spread over a large distance in the form of structural noise. This is due to ultra-low attenuation of sound energy in building construction materials.

Fans, pumps, elevator winches and other mechanical equipment of buildings are sources of both air and structural noise. For example, ventilation plants create strong air noise. If you do not accept the appropriate measures, this noise applies together with the air flow through the ventilation channels and through the ventilation grids penetrates the room. In addition, fans, like other mechanical equipment, as a result of vibration, cause intense sound oscillations in floors and walls of buildings. These fluctuations in the form of structural noise are easily applied by building designs and penetrate even far from the noise sources of the room. If the equipment is installed without the corresponding sound and vibration-insulating devices, in the basements, the foundations are formed oscillations of sound frequencies transmitted along the walls of buildings and spreading over them by creating noise in apartments.

In high-rise buildings, the source of noise can be elevator installations. The noise occurs during the work of the elevator winch, the movement of the cabin, from shocks and shoes of shoes on the guides, clattes of floor switches and, especially, from shocks of sliding doors of the shaft and cabins. This noise applies not only by air in the mine and staircase, but mainly according to the designs of buildings due to the rigid fastening of the elevator mine to the walls and overlaps.

The noise level penetrating the premises of residential and public buildings from the operation of sanitary and engineering equipment mainly depends on the effectiveness of noise immunity measures that are used in the installation and operation process.

The level of household noise is given in Table. 94.

Table 94 Equivalent sound levels from various sources of noise in apartments, dBA

Practically the sound level in residential rooms from various noise sources can achieve a significant amount, although on average it rarely exceeds 80 dBA.

The most common source of urban (external) noise is transport: cargo vehicles, buses, trolley buses, trams, as well as railway transport and civil aviation aircraft. Complaints of the population on the noise of transport are 60% of all complaints about urban noise. Modern cities are overloaded with transport. In some sites of urban and district highways, transport flows reach 8,000 units in 1 h. The largest transport load is accounted for on the streets of the administrative and cultural centers of cities and highways connecting residential areas with industrial nodes. In cities with developed industry and cities-new buildings, a significant place in the transport flow occupies a cargo transport (up to 63-89%). With an irrational organization of the transport network, the transit cargo flow passes through residential areas, resting places, creating a high level of noise on the adjacent territory.

Analysis of noise maps in the cities of Ukraine showed that most urban main streets of the district values \u200b\u200bon noise levels refer to class 70 dBA, and urban value - 75-80 dba.

In cities with a population of more than 1 million people on some trunk streets, the sound level is 83-85 dBA. SNiP II-12-77 permits the noise level on the facades of residential buildings overlooking the main street equal to 65 dBA. Taking into account the fact that the sound insulation of the window with an open window or fraumuga does not exceed 10 dBA, it is quite clear that noise exceeds the permissible indicators by 10-20 dba. On the territory of the neighborhoods, places of recreation, in the zones of therapeutic and university towns, the level of acoustic pollution exceeds the normative 27-29 dBA. Transport noise in the primary territory persistently persists for 16-18 h / day, the movement subsides only for a short period - from 2 to 4 hours. The level of transport noise depends on the size of the city, its national economic importance, saturation of individual transport, public transport systems, density Street road network.

With an increase in the number of population, the coefficient of acoustic discomfort increased from 21 to 61%. The average city of Ukraine has an area of \u200b\u200bacoustic discomfort approximately 40% and equated to the city with a population of 750 thousand people. In the general balance of acoustic regime, the share of noise noise is 54.8-85.5%. The zones of acoustic discomfort are increased by 2-2.5 times with an increase in the density of the street-road network (Table 95).

Table 95 Equivalent levels of sound of urban streets at street network density 3 km / km2, dBA

On noise regime, especially large cities, the noises of railway transport, trams and open metro lines are significantly affected. Not only railway inputs, but also railway stations, railway stations, trailers and travel economy with operations of loading and unloading, access roads, depot, etc. The sound level of the territories can reach such objects 85 dBA and more. Analysis of the noise regime of the residential building placed near the Railwayways of the Crimea showed that in these territories acoustic indicators of the noise regime are higher than those permissible for 8-27 dB and during the day and 33 dba at night. Along the railway tracks, corridors of acoustic discomfort width 1000 m and more are formed. The average noise level of loud-speaking communication at the stations at a distance of 20-300 m reaches 60 dBA, and the maximum - 70 dBA. These indicators are high and near the sorting stations.

In major cities, the metro lines are becoming increasingly distribution, including open. In the open areas of the metro station, the level of sound from trains is 85-88 dba at a distance of 7.5 m from the way. Almost the same levels of sound are characteristic of both the city tram. Acoustic discomfort from rail vehicles is complemented by vibration, which is transmitted to the designs of residential and public buildings.

The noise regime of many cities largely depends on the location of civil aviation airports. The use of powerful aircraft and helicopters in combination with a sharp increase in air traffic intensity led to the fact that the problem of aviation noise in many countries has become almost the main problem of civil aviation. It has been established that aviation noise within a radius of up to 10-20 km from the runway adversely affects the well-being of the population.

Table 96 Noise Characteristics of the Transport Flow

Noise characteristic of ground vehicle is an equivalent level of sound (La eq) at a distance of 7.5 m from the axis of the first strip of movement. Characteristics of transport flows on the streets and roads of various purposes in the peak hours are given in Table. 96.

By spectral composition, the transport noise can be low- and mid-frequency and is capable of spreading to a significant distance from the source. It depends on the intensity, speed, character (composition) of the transport flow and the quality of the highway coverage.

Acoustic studies in natural conditions allowed to establish the basic dependencies between the conditions of traffic and noise level from the city's transport highways. There are data on the effect on the noise level of the specific weight in the flow of crews with a diesel engine, the width of the distribution band, the presence of trams, longitudinal slopes, etc. This allows today to determine the calculated method of the expected noise of the street road network to the perspective and build noise cards cities.

The value of railway transport in suburban and long-distance transportation of the population increases every year due to rapid development suburban areas with satellite cities, workers and country villages, large industrial, agricultural enterprises, airports, scientific and educational institutions, recreation areas, sports, etc. Noise occurs during the movement of trains and processing them at sorting stations. The noise of the train consists of the noise of engines of locomotive and wheel systems of wagons. The greatest noise during the operation of diesel locomotives occurs near the exhaust pipe and the engine (100-110 dBA).

The sound level created by passenger, cargo and electric trains depends on their speed. So, at a speed of 50-60 km / h, the sound level is 90-93 dBA. Spectral components and levels depend on the types and technical status of trains, equipment paths. The noise spectra from the wheels of trains have a mid-frequency character. The noise characteristics of railway transport facilities at a distance of 7.5 m from their borders are given in Table. 97.

Table 97 Noise level from railway transport facilities, dBA

Industrial enterprises and their equipment are often sources of significant external noise On the adjacent residential area.

Sources of noise at industrial enterprises are technological, auxiliary equipment and ventilation systems. Approximate levels of external noise from some industrial enterprises are shown in Table. 98.

The noise created by the enterprise largely depends on the effectiveness of noise immunity measures. So, even large ventilation plants, compressor stations, various engine testing stands can be equipped with noise-jamming devices. Enterprises need to be fencing outdoor soundproofing screens. This reduces the intensity of noise, which extends to the adjacent territory. But it should be remembered that

When solving the issue of protection of the population from noise, it is also necessary to take into account intra-quarterly sources. The noise characteristics of these sources in the equivalent levels of sound (dBA) at a distance of 1 m from the borders of household courtyards, trade, public catering and consumer services, physical education sites and sports facilities are given in Table. 99.

Table characteristic of intra-quarter sources of noise, dB a

99 Soundproofing screens (fencing) enhance the noise on the territory of the enterprise or highway.

The effect of noise on the human body. A person lives among various sounds and noise. Some of them are useful signals that give the opportunity to communicate, correctly navigate in the environment, to take part in the labor process, etc. Others interfere, annoy and can even damage their health.

A well-known influence on the human body of natural medium noise (leaves, rain, rivers, etc.) is known. Statistics suggests that people working in the forest, the river, at sea, less often than residents of cities, there are diseases of the nervous and cardiovascular system. It has been found that the rustle of the leaves, the singing of birds, the murmur of the stream, the sounds of the rain and the nervous system are lying. Under the influence of the sounds published by the waterfall, the work of the muscles is intensified.

The positive impact of harmonious music was known since a long time. Let us recall the lullabic (quiet gentle monotonous tunes), the removal of the nervous stress of the murmur of streams, gentle noise of sea waves or bird singing. Also known is the negative effect of sound. One of the heavy penalties in the Middle Ages was the impact of sounds from the blows of a mighty bell when the doomed died in terrible flour from unbearable pain in the ears.

This determines the theoretical and practical importance of studying the nature of the effect of noise on the human body. The main purpose of the study is to identify the threshold of the adverse effect of noise and the rationale for hygienic standards for various contingents of the population, various conditions and human stay (residential, public buildings, industrial premises, children's and medical and preventive institutions, areas of residential areas and recreation sites).

Significant theoretical interest is the study of pathogenesis and the mechanism of action of noise, the processes of adaptation of the body and remote consequences with long-term effects of noise. Studies are usually carried out under experimental conditions. To study the nature of the effect of noise per person is difficult, since the processes of interaction between physical and chemical environmental factors with its body are also complex. Individual sensitivity to the noise of various age-genital and social groups is also unequal.

The human response to noise depends on which processes are dominated in the central nervous system - excitation or braking. Many sound signals entering the bark of a large brain cause anxiety, fear, premature fatigue. In turn, this may adversely affect health. The effect of the effect of noise per person is wide: from subjective sensation to objective pathological changes in the hearing body, central nervous, cardiovascular, endocrine, digestive systems, etc. Consequently, the noise is valid for vital organs and systems.

These categories of the influence of sensitive acoustic energy per person can be distinguished:

1) the effect on the hearing function, which causes auditory adaptation, auditory fatigue, temporary or constant hearing loss;

2) a violation of the ability to transfer and perceive the sounds of speech communication;

3) irritability, anxiety, sleep disorder;

4) Changes in human physiological reactions on stress signals and signals that are not specific to noise influence;

5) influence on mental and somatic health;

6) Impact on production activities, mental work.

City noise is perceived primarily subjectively. The first indicator of his adverse action is the complaints of irritability, anxiety, sleep disorder. In the appearance of complaints, the noise level and the time factor are crucial, but the degree of unpleasant sensations depends on the extent to which noise exceeds the normal level. A significant role in the emergence of a person's unpleasant sensations play its attitude towards the source of noise, as well as information laid in noise.

Thus, the subjective perception of noise depends on the physical structure of the noise and psycho-physiological characteristics of a person. The reactions to the noise of the population is heterogeneous. Super sensitive to noise 30% of people, have normal sensitivity - 60%, insensitive - 10%.

The type of psychological and physiological perception of acoustic stress is influenced by the type of higher nervous activity, an individual biorhythmic profile, character of sleep, the level of physical activity, the number of stressful situations during the day, the degree of nervous and physical overvoltage, as well as smoking and alcohol.

We present the results of sociological research on the evaluation of the noise, carried out by the staff of the Institute of Hygiene and Medical Ecology. A.N. Marzeeva AMN of Ukraine. Survey 1500 residents of noisy streets

(La eq \u003d 74 - 81 DBA) showed that 75.9% complained about the noise of transport origin, 22% - to the noise of industrial enterprises, 21% - on household noise. In 37.5% of respondents, the noise caused anxiety, in 22% - irritation and only 23% of respondents - did not complain about him. At the same time, those who had the defeat of the nervous, cardiovascular systems and digestive organs were most suffering. Permanent accommodation in such conditions may cause peptic disease Stomach, gastritis due to violation of the secretory and motor functions of the stomach and intestines.

The reaction of the population is shown in Table. 100.

Table 100 population reaction to noise

In areas with a high noise level, most residents note deterioration of well-being, more often apply to the doctor, take sedatives. During a polling of 622 residents of quiet streets (La eq \u003d 60 dBA) complained about 12% vehicles, 7.6% on household noise - 8%, on the noise of industrial origin - 8%, for aviation and rail noise - 2.8%.

There is a direct dependence of the number of complaints of the population from the sound level on the primary territory. Thus, with an equivalent audio level of 75-80 dBA, more than 85% of complaints are registered, 65-70 dBA - 64-70%. When the sound level of 60-65 dBA, almost half of the respondents complained about the noise, 55 dBA - the third part of the population was concerned, and only at noise level 50 dba complaints were practically no (5%). The last two levels are acceptable for the territories of residential building. A dream is violated usually at the sound level of more than 35 dBA. The population's reaction to the transport noise is practically independent of gender, age and profession.

In modern urban environments, the human auditory analyzer is forced to work with high voltage against the background of transport and housing noise, which masks useful sound signals. Therefore, it is necessary to determine the possibilities of adapting the organ of hearing, on the one hand, and safe levels of noise, the action of which does not violate its functions - on the other.

The thresholds of the auditory characterize sensitivity. They are determined on pure tones in the frequency range from 63 to 8000 Hz by the method of tonal audiometry in accordance with GOST "Noise. Methods for determining human hearing loss." The highest sensitivity of the ear to sounds in the frequency range of 1000-4000 Hz. It quickly decreases at a distance in both directions from the highest sensitivity zone. In the frequency range of 200-1000 Hz, the sound force of the sound is 1000 times greater than "in the frequency range of 1000-4000 Hz. The higher the sound tonality or noise, the stronger its adverse effect on the hearing body.

Sound waves with appropriate intensity and frequency are specific irritants for the organ of hearing. At a fairly high level of noise and a short influence there is a decrease in audibility, which leads to a temporary increase in its threshold. Over time, she can recover. The long effect of the sound of high intensity may determine the irrevitable hearing loss (hearing loss), which is usually characterized by the magnitude of the constant displacement of the sensitivity threshold.

Transport noise significantly affects the functional state of the auditory analyzer. Thus, in a soundproofing chamber with a two-hour exposure, even the relatively low sound level (65 dB) leads to a loss of hearing more than 10 dB at low frequencies, which corresponds to a low-frequency spectrum of transport noise. The level of noise 80 dBA reduces hearing sensitivity at \\ 1-25 DH in a wide range of low, medium and high frequencies, which can be regarded as the fatigue organ of hearing.

A second signal system associated with verbal alarm, speech has a huge importance for communication. In urban residential buildings located along the highways, the population often complains about the poor perception of speech, which is explained by the camouflage of individual sounds of speech by transport noise. It has been established that noise violates speech intelligibility, especially if its level exceeds 70 dBA. At the same time, a person does not disassemble from 20 to 50% of words.

The noise through conducting the sound analyzer paths affects the various centers of the brain, changes the relationship between the processes of the highest nervous activity, violates the equilibrium of excitation and braking processes. In this case, reflex reactions are changed, pathological phase states are detected. The prolonged effect of noise activates the structures of the reticular formation, as a result of which there is a persistent violation of the activities of different systems of the body.

For studying functional state The central nervous system is widely used by the method of determining the hidden (latent) time of the reflex reaction - chronoreflexometry. Latent time in a quiet apartment (40 dBA) in a group of people in a calm state on the light stimulon is an average of 158 ms, on sound - 153 ms; During rest on the territory of the microdistrict in noisy conditions, it increased by 30-50 ms. The shift criterion is to exceed the reaction time by 10 ms. Thus, the transport noise causes braking processes in the core of a large brain, which negatively affects the behavior of a person, convention and reflex activity.

Important indicators of the functional state of the central nervous system when exposed to various environmental factors are the ability to concentrate attention and mental performance. It has been proven that the violation of the state of the central nervous system under the influence of noise leads to a decrease in attention and performance, especially mental. At noise level, over 60 dBA, the speed of transferring information, the amount of short-term memory, quantitative and qualitative indicators of mental performance, changes the reaction to various life situations.

Special attention deserves the results of studying the effect of noise on the cardiovascular system. Under its effect, the pulse is accelerated or slowed down, blood pressure increases or decreases, the ECG, plethic and reoencephalogram is changed. In the laboratory conditions after a two-hour action of intensive transport noise (80-90 dba), a noticeable decrease in heart rate due to the elongation of the heart cycle and the characteristic change in individual ECG indicators was revealed. Blood pressure fluctuations reaches 20-30 mm Hg. Art. CHSS changes identified by variation pulsometry after a two-hour exposure of noise from flights and testing engine aircraft with high sound levels (up to 90 dBA), were characterized as vagotonic.

Under the influence of noise from the flying aircraft, the resistance of peripheral blood flow increases (by 23%), changes in the brain circulation. With the help of reophiecephalography, an increase in tone and a decrease in the filling of the blood vessels of the brain is revealed. Based on this, it is assumed that the possible role of transport noise in the development of cardiovascular diseases among large cities in the development of cardiovascular diseases.

Noise is one of the stimuli at night: he breaks sleep and rest. Under his influence, a person falls asleep badly, often wakes up. Sleep surface, intermittent. After such a dream, a person does not feel rested. Studying the nature of sleep in residents of houses located on the streets with different levels of noise, indicates that the dream is dramatically violated at the level of 40 dBA sound, and if it is 50 dBA, the falling period increases to 1 h, duration deep sleep It is reduced to 60%. The inhabitants of the quiet districts are normal, if the noise level does not exceed 30-35 dBA. At the same time, the saturation period is 14-20 minutes, sleep depth is 82% (Table 101).

The lack of a normal rest after a labor day leads to the fact that fatigue does not disappear, but gradually goes into chronic, which contributes to the development of hypertension, diseases of the central nervous system, etc.

Table 101 Sleep Indicators Depending on Noise Conditions

Some countries have a direct relationship between the growth of noise in cities and an increase in the number of persons with diseases of the nervous system. French scientists believe that over the past 4 years, the increase in noise contributed to an increase in the number of neurosis cases in Paris from 50 to 70%.

City noise plays a certain role in the pathogenesis of hypertension. These data were confirmed during the study of the incidence of women (home owners) in the cities of Ukraine. There is a relationship between the defeat of the central nervous and cardiovascular system, the noise levels and the duration of residence in noisy urban conditions. Thus, the overall incidence of the population increases after 10 years of residence in conditions of constant effects of noise by force 70 dBA and more.

The effect of noise is enhanced if a person is experiencing its total impact at work and in everyday life.

With the participation of various specialists, a mass integrated study of the health of employees of project institutions living and working in homes located along highways with intensive traffic movement was carried out. It has been established that the sound level in apartments and at workplaces was 62-77 dBA. The control group included persons who lived in apartments with a sound level that meets the regulatory requirements (36-43 dBA). During a survey, 60-80% of the inhabitants of the experimental area revealed a strong irritant effect of noise, (in control - 9%). There are changes in the threshold of the hearing sensitivity in persons who lived in a noisy area, compared with the indicators in persons of the control area: at frequencies of 250-4000 Hz difference was 8-19 dB.

When analyzing the audiograms of persons who lived in a noisy region of 10 years and more, a difference in 5-7 dB at all frequencies was noted. Functional disorders of the central nervous system are also characteristic, as evidenced by the change in the hidden time of the conditionaloreflex reaction to the sound (18-38 ms) and light (18-27 ms) stimuli. The tendency to increase the number of patients with vegetable dystonia, hypertensive disease, atherosclerosis of the brain vessels with functional disorders central nervous system, asthenic syndrome, as well as an increase in cholesterol content in the blood.

We studied the consequences of the long exposure to high-level aviation noise at work and at home. Installed an increase in the risk of cardiovascular diseases, as according to the functional state blood systemand according to the results of studying incidence with temporary disability (number of cases and days). The activity of the cardiovascular system is usually broken earlier than hearing. With a high level of noise load at work, the incidence of digestion organs increased, in particular the ulcer of the stomach and duodenum.

All disorders arising under the influence of the combined effects of industrial, transport and housing noise are a symptom complex of noise disease.

Hygienic rationing of noise levels. To eliminate the unfavorable effect of noise on human health, sanitary and hygienic standards of permissible sound levels are crucial, since they determine the development of certain events to combat noise in cities.

The purpose of hygienic rationing is the prevention of functional disorders and diseases, excessive fatigue and reduction of working capacity with a short-term or long-term effects of noise. The main principle of the regulation of noise in our country is a medical and biological substantiation of norms through laboratory and mineral research in natural conditions for noise on various age and professional groups, and not a feasibility study, as is observed in some countries. As a result of numerous and versatile studies, invalid and threshold noise levels were identified, which formed the basis of rationing.

This level of noise is considered to be permissible, with a long-term effect of which does not negative changes in physiological reactions, the most sensitive and adequate noise, and in subjective well-being. "The sanitary standards of permissible noise in the premises of residential and public buildings and on the territory of residential building" (No. 3077-84) are governed by the permissible noise parameters for various people's stay depending on the main physiological processes inherent in a certain type of human activity in these conditions. So, the leading physiological processes in the residential rooms during the day are associated with active recreation, homework, watching and listening to television and radio programs, in bedrooms - with sleep, in classes, audiences - with educational process, speech communication, in reading rooms - with mental labor , in medical and preventive institutions - with restoration of health, rest, etc.

The normalized parameters of constant noise are the levels of sound pressure (dB) in octave frequency bands with medium meterometric frequencies 63, 125, 250, 500, 1000, 2000, 4000 and 8000 Hz and the sound level (dBA).

The normalized parameters of non-permanent noise are equivalent in energy (LA eq, dBA) and maximum (LA max, dBA) sound levels. In tab. 102 shows the regulatory levels of noise in different premises of buildings and in the territories of development.

To determine the permissible sound pressure levels in the octave frequency bands, sound levels or equivalent sound levels, depending on the location of the object, the nature of noise penetrating into the room or to the territory, corrections are made to the normative levels of noise (Table 103).

Evaluation of non-permanent noise on (compliance with permissible levels) should be carried out simultaneously on equivalent and maximum sound levels. At the same time, La Max should not exceed La eq more than 15 dBA.

Table 103 Amendments to regulatory octave sound pressure levels and sound levels

Amendments to the regulatory levels of noise are taken into account only for external sources of noise in residential premises, bedrooms and in residential buildings.

The norms of permissible noise levels entered the construction rates and rules for "noise protection" and GOST "noise. Permissible levels in residential and public buildings." The sanitary standards of permissible noise allow to develop technical, architectural and planning and administrative activities aimed at creating the buildings in urban development, buildings of various purposes of such a noise regime that meets hygienic requirements. It helps to preserve the health and performance of the population.

The task of hygienists is to further improve the standards, taking into account the overall noise load permitting large cities in everyday life, in production and during the use of transport.

Noise protection measures. For protection against noise, such measures are used: eliminating the causes of noise formation or the weakening of noise in the source of the occurrence; Weakening noise on the path of its distribution and directly in the object of protection. To protect against noise, various activities are carried out: technical (weakening noise in the source); architectural and planning (rational methods of layout of buildings, developmental territories); construction and acoustic (noise restriction on distribution path); Organizational and administrative (restriction or prohibition, or regulation in the operation time of certain sources of noise).

The weakening of noise in the source of its occurrence is the most radical way to combat it. However, the effectiveness of measures to weaken the noise of cars, mechanisms and equipment is low and therefore they need to be developed at the design stage.

The weakening of noise on the path of its distribution is provided by a complex of construction and acoustic measures. These include rational planning solutions (first of all, the removal of noise sources for the proper distance from objects), sound insulation, sound absorption and soundness of noise.

Events on the weakening of noise should be envisaged at the stage of designing the general plans of cities, industrial enterprises and planning premises in individual buildings. So, it is unacceptable to place objects requiring protection against noise (residential buildings, laboratory-constructors, computing centers, administrative buildings, etc.),

In the immediate vicinity of noisy shops and aggregates (test boxes of aircraft engines, gas turbine installations, compressor stations, etc.). The most noisy objects should be combined into separate complexes. When planning premises inside buildings include the maximum possible removal of quiet rooms from rooms with intense noise sources.

To reduce noise penetrating insulated rooms, it is necessary to: apply for overlapping, walls, partitions, solid and glazed doors and windows materials and designs that ensure proper sound insulation; use the sound-absorbing cladding of the ceiling and walls or artificial sound absorbers in isolated rooms; provide acoustic vibration insulation of aggregates located in the same building; apply sound insulation and vibration-fixing coatings on the surface of pipelines passing in the room; Use silencers in mechanical ventilation and air conditioning systems.

The normalized parameters of sound insulation of structures enclosing residential premises are indexes of air sound - 1B (dB) and the above level of shock sound under the overlap - 1U (dB). Sound insulation properties of windows and balcony doors in each case of construction and reconstruction of a residential building are determined by special calculations. The windows must have quality certificates, indicating the parameters of their sound insulation properties in the closed state and with open elements intended for ventilation, frequency response and frequency of resonance. The frequency of wind resonance should not exceed 63 Hz. Soundproofing window characteristics should provide sound and sound pressure levels in a residential room in a proper air exchange in this climatic area for different seasons of the year.

When choosing the sound insulation characteristics of intercom and intercianar floors and partitions, intra-wood partitions and doors should be proceeding from the noise characteristics of household machinery and instruments. According to L.A. Andrichuk (2000), the acoustic load on a person in a residential environment from household electrical machines and devices should not exceed the maximum permissible level (17 μA / h per day). It is calculated by the formula:

D \u003d 4-10_L ° -oO01 ^ -t,

Where La is an equivalent level of sound (dBA), T is the duration of the effects of noise.

The hygienic regulation of the noise of household electrical machines and devices is provided for equivalent sound levels for short-term operation devices (up to 20 minutes) not exceeded 52 dBA, long (up to 8 hours) - 39 dB, very long (8-24 h) - 30 dBA. Although the operation of household electric machines and devices with levels of corrigated sound power of more than 81 dba with hygienic positions is invalid, when choosing sound insulation elements for residential buildings, you need to focus on technically achievable noise levels from home appliances.

The levels of sound and sound pressure from household electrical machines and devices need to be calculated for the aggreed noise formation conditions, taking into account the volume of the room, the spatial angle of radiation, the distance, the acoustic characteristics of the enclosing room elements, etc. The acoustic characteristics of the auxiliary and residential premises of the residential building should be such So that with the regulated use of household appliances, do not create noise, which can adversely affect not only the operator, but also on other residents of the apartment and buildings.

In residential buildings and hostels can not be placed boiler houses and pumping, built-in and attached transformer substations, automatic telephone stations, administrative institutions of urban and district purposes, medical institutions (except for women's consultations and dental polyclinic), dining rooms, cafes and other catering enterprises with the number of seats over 50, house kitchens with productivity over 500 dinners per day, shops, workshops, facilities for receiving dishes and other non-residential premises in which vibration and noise may occur.

The machine room of the elevators is unacceptable to position directly above and under residential premises, as well as next to them. Elevator shafts should not fit the walls of the residential rooms. Kitchens, bathrooms, bathrooms should be combined into separate blocks adjacent to the walls of staircases or to the same blocks of adjacent rooms, and separate from residential premises by a corridor, a tambour or hall.

The installation of pipelines and sanitary devices is prohibited on the enclosing structures of residential rooms, as well as accommodation next to them bathrooms and sewering risers.

In all public, and sometimes in residential buildings use ventilation systems, sometimes - air conditioning systems and air heating With mechanical equipment, can create significant noise.

To reduce air noise sound pressure levels, the following activities are used:

A) Reducing the sound power level of noise sources. This is achieved with the help of fans and end tools performed from an acoustic point of view, using the rational mode of their operation;

B) reducing sound power over the path of sound distribution by equipment of silencers, rational planning of buildings, the use of sound insulation structures with increased sound insulation (walls, overlappings, windows, doors) and sound-absorbing structures in rooms with noise sources;

C) Changes in the acoustic properties of the room in which the calculated point is located, by increasing sound absorption (the use of sound-absorbing coating and artificial sound absorbers).

To attenuate the noise spreading through the channels of ventilation systems, air conditioning and air heating, special silencers should be used (tubular, cellular, plate and chamber with sound-absorbing material), as well as lined with inside sound-absorbing materials of air ducts and Signs. The type and size of the muffler are chosen depending on the required noise level, the permissible air flow rate and local conditions. The schemes of such designs are shown in Fig. 102. Tubular silencers are used with air ducts up to 500 x 500 mm. For large sizes of air lines, it is advisable to use plate or chamber silencers. The weakening of the structural noise caused by the operation of the fans reach the vibration insulation of the fan and the installation of flexible tarp inserts between the fan and the aircase suitable to it.

Fig. 102. Ventilation silencers

A - tubular; b - lamellar; in - cellular;

G - cylindrical

Fig. 103. Vibration insulation of the pumping unit: 1 - reinforced concrete base plate; 2 - flexible inserts; 3 - vibration of the pipeline; 4 - vibration insulators; 5 - riser with spring gasket

Sources of noise in water supply systems, sewage and heating systems in buildings are pumping units, various equipment, including sled and pipelines and pipeline itself. It is created as an air noise penetrating directly into the room where the noise source is installed and the structural, propagating from the noise source along the pipeline and enclosing structures. We can weaken the air noise created by pumps by selecting the most advanced designs of pumps, static and dynamic equipment balancing or by mounting pumps into the casing of the corresponding structures. The weakening of structural noise is achieved using the installations between the concrete base and the pump of vibration insulators, the insulation of pumping units that are suitable for the pipeline, providing flexible inserts. The diagram of vibration insulation of the pump is shown in Fig. 103.

Soundproofing of premises from air noise is the weakening of sound energy during the transmission process through the fencing. Most often, sound insulation fences are walls, partitions, windows, doors, overlap.

The sound insulation capacity of single-layer fences depends on many factors, but first of all - from their mass. To ensure high sound insulation, such fences must have a large mass.

Soundproofing from shock noise is called the ability to overlapping noise in the room under the overlap during its strengthening caused by the walking, rearrangement of furniture, etc. To ensure regulatory sound insulation from the air noise of single-layer interstricular enzypsy structures in residential buildings, their surface weight should be at least 400. kg / m2. To reduce the mass of soundproofing fences when providing regulatory sound insulation from air noise, it is necessary to use double with air layers and multilayer fences, structures.

Currently, multilayer structures are used in construction practice more and more. In some cases, they make it possible to obtain significant additional insulation compared to single-layer structures of the same mass (up to 12-15 dB).

In the floors to ensure the regulatory isolation of shock and air noise, the floor is made on an elastic basis (floating floor) or use soft roll coatings. The joints between the internal enclosing structures, as well as between them and other adjacent structures, should be equipped in such a way that there are no cracks and cracks that weaken isolation (Fig. 104) during operation.

Fig. 104. Scheme of overlapping structures: A - Floating floors on a continuous flexible basis (1 - floor coating; 2 - plate of the national team or monolithic screed; 3 - sound insulation flexible gasket; 4 - carrier part of the overlap; 5 - plinth; b - floating floor on tape or artificial gaskets; in - overlapping with sound insulation materials (1 - soft rolled floor; 2 - overlapping; 3 - plinth)

To enhance sound insulation, also double doors with a tambour. Doors focus supply with elastic gaskets. Walls in the vestibule are appropriate to be tinted with sound-absorbing material. Opening doors should in different directions.

Double windows are better insulated from air noise (up to 30 dB) than paired (20-22 dB).

Recently, "sound insulation windows", which provide high sound insulation and at the same time allow you to air the room. These are two deaf frames located at a distance of 100 mm and more than one of the other, with sound insulation facing along the contour. Use glass of various thickness or in one frame of a pack of two glasses. In the wall under the window, equip the hole in which the box is installed in the form of a silencer with a small fan that provides air inflows into the room.

Sound absorbing structures are designed to absorb sound. These include sound-absorbing cladding of plane surfaces of rooms and artificial sound absorbers. Sound-absorbing structures are very widely used. Most often used sound-absorbing cladding: in educational, sports, spectacular and other buildings to create the best acoustic conditions for speech and music perception; in manufacturing workshops, offices and other public premises (typewritten offices, engineering stations, administrative premises, restaurants, railway stations and airbrokes, shops, dining rooms, banks, branches, etc.); In the premises of the corridor type (schools, hospitals, hotels, etc.) to prevent noise spread.

Sanitary and hygienic requirements for sound-absorbing structures are primarily in the fact that they should not worsen the hygienic conditions due to the crepe of fibers or particles of the material, contribute to the accumulation of dust. The ease of purification of dust sound-absorbing structures is of particular importance in buildings both with increased sanitary and hygiene requirements (hospitals) and with increased allocation of dust (most industrial enterprises).

The effectiveness of sound-absorbing cladding in noisy rooms depends on the acoustic characteristics of the room, the characteristics of the selected structures, the method of their placement, the location of noise sources, the size of the room and localization of the calculated points. It usually does not exceed 6-8 dB.

Activities to combat urban noise can be divided into two groups: architectural and planning and acoustic.

Together with the development of measures to reduce the noise of transport sources, the problem of combating noise that distributes these sources to the environment is arising. Solve this problem in two ways: planning of general town planning measures in the process of compiling general plans of cities, projects of detailed layout of residential areas and microdistricts, as well as the development of special noise protection devices, insulating, absorbing and reflecting noise.

Various administrative measures can be used. These include: the redistribution of traffic flows by the streets of the city; restriction of movement at different times of the day in one way or another; Changing the composition of vehicles (for example, prohibition of use on some streets of trucks and buses with diesel engines), etc.

When developing projects for planning and building cities to protect against noise, you can use both natural conditions (terrain and green planting) and special structures (screens near the transport highways). We can also use rational methods of zoning territory under the conditions of the noise regime for certain types of buildings, sites and sites for recreation, household needs, etc.

Consider possible options for protection against noise in cities. First of all, in order to protect against noise when designing cities and other settlements, it is necessary to clearly divide the territory for its functional use on the zones: residential, industrial (production), utility-warehouse and external transport. Industrial (production) and municipal-warehousing zones designed for large freight traffic on the transport highways, so that they do not cross the residential zone and do not embed it into it.

To protect against noise when designing an external transport system, we must provide in the cities of bypass railway lines (to pass transit trains outside the city), place sorting stations outside the settlements, and technical stations and parking lots of backup rolling stock, railway lines for freight traffic and access ways - outside the residential territory; Separate new railway lines and stations during new construction from residential building of cities and other settlements of SZZ; Comply with the proper distance from the borders of airports, factory, military airfields to the borders of the residential building. The width of the SPZ should be justified by the Akuk

The ticnative calculations and sanitary standards regulated by DBN 360-92 * "Urban planning. Planning and building of urban and rural settlements" and SNiP "Protection against noise". In fig. 105 shows a schematic diagram of the settlement, taking into account protection against external noise.

When laying new or reconstruction of the main streets and roads on the residential territory, it is necessary to provide for protection against transport noise, justified by acoustic calculations. High-speed roads and roads of a citywide value with mainly by freight transport should not cross the residential territory. In the residential territories, laying high-speed roads with the appropriate justification is allowed in tunnels or recesses. Rational bypass roads that guide transit flows outside the city.

Elements of the relief should be used as natural barriers to noise propagation paths. If necessary, laying trunk streets and roads on bulk and overpass to install noise protection screens.

When designing a street-road network, the maximum possible consolidation of intermographic areas should be provided, a decrease in the number of intersections and other transport hubs, a device of smooth curvilinear road compounds. On the territory of residential areas it is necessary to limit the end-to-end traffic.

In the architectural and planning structure of residential areas and microdistrict, the following noise protection methods are used: removal of residential building from noise sources; the location between the sources of noise and residential building of buildings-screens; The use of rational in terms of protection against the noise of composite methods of grouping residential buildings.

The functional zoning of the territories of microdistricones should be carried out, taking into account the need to place residential building and children's preschool institutions in the areas most remote from noise sources, transport highways, parking lots, garages, transformer substations, etc. In zones adjacent to noise sources, you can build buildings in areas Which are allowed higher levels of sound. These are enterprises of household services, trade, catering, utilities, administrative and economic and public institutions. Shopping centers and service blocks are usually built on the border of microdistricon along the transport highways in the form of a single complex.

If the living building needs to be placed on the border of the neighborhoods along the transport highways, it is advisable to use special types of noise-proof residential buildings. Depending on the conditions of insolation, it is recommended to build: noise-proof residential buildings, the architectural and planning solutions of which are characterized by the orientation towards the sources of noise of the auxiliary premises and no more than one residential room without sleeping places of multicoming apartments; Noise-proof residential buildings with increased sound insulation properties of external enclosing noise-oriented constructions and with built-in supply ventilation systems.

To ensure sanitary standards in apartments and on the territory of the microdistrict, it is necessary to use composite techniques for grouping of noise-proof buildings based on the creation of a closed space. When the residential building is arranged along the transport highways, one should not resort to composite receptions of the grouping of residential buildings, which are based on the disclosure of space towards the carriageway.

If architectural and planning activities (ruptures, developmental techniques, etc.) do not provide a proper noise regime in buildings and on the territory of a residential neighborhood, as well as to save the territory necessary to comply with territorial gaps with transport highways, it is advisable to apply construction-acoustic Methods: Shu-regular structures and devices, screens, noiseing strips of landscaping, and for residential buildings Also designs of window openings with increased sound insulation.

Various buildings and structures can be used as screens: buildings with reduced noise regime requirements; Noise-proof residential buildings; Artificial or natural elements of relief (removing, ravines, earth shafts, mounds, mounds) and walls (roadside retaining, enclosing and noise protection). Noise protection screens are advisable to place as close as possible to the noise source.

Buildings with reduced requirements for noise regime (enterprises of household service, trade, catering, utilities; public and cultural and educational, administrative and economic institutions) and noise-proof residential buildings should be placed along the sources of noise in the form of a frontal, as continuous, development. The premises of administrative, public and cultural and educational institutions with increased demands on acoustic comfort (conference room, reading rooms, visual halls of theaters, cinemas, clubs, etc.) should be erected on the opposite of the sources of noise. They separate them from the mains of corridors, lobby, halls, cafes and buffets, auxiliary premises.

Currently, the principle of shielding noise is beginning to be applied in domestic town planning practice.

As an additional means to protect against noise, you can use special noiseless bands of green plantings. There are several bands with ruptures between them, equal to the height of trees. The bandwidth must be at least 5 m, and the height of the trees - at least 5-8 m. On the noise-protective bands of the crown of trees should be tightly closed with each other. Under the crowns, a thick shrub in a chess order is planted. Play fast-growing, stable species of trees and shrubs. However, the effectiveness of even special noise protection strips of green plantings is low (5-8 dBA).

In many cases, when buildings are located on urban and district trunk streets and along high-speed roads, special soundproof houses are erected with increased soundproofing of external fences of all rooms overlooking the "noisy facade". In such noise-proof buildings used as a screen to limit the zone of noise inclusion in the residential territory, provide for a special layout of premises, in which spacerooms, operating rooms, chambers are focused on the facade, opposite to the trunk street (Fig. 106).

Fig. 106. Plans of the sections of noise-proof buildings. Points indicate noise sources. K - Kitchen, P - Hallway, C - Bedroom

At the stage of developing a master plan of the city, it is advisable to draw up a noise map of the street-road network and the largest sources of industrial noise. Noise maps are based on the results of inventive instrumental measurements in vivo or settlement path. The need and advantage of the use of territorial gaps, shielding structures and noise protection bands of green spaces is determined by calculating the sound level of LA ter in the calculation point on the territory of the object that must be protected from noise:

^ And ter. - ^ a eq - ^ "-" and dist. - ^ * ^ and ECR. - ^^ and green\u003e

Where La eq is the noise characteristic of the source of noise (dBA); Dya Dast - Reducing the sound level (dBA) depending on the distance between the noise source and the calculation point; Ala ECR - reducing sound levels by screens; Ala is green. - Reduced sound levels with strips of green plantings. At the same time, the calculated level (BATER) should not exceed the permissible (Ladop) (see Table 102).

Sanitary overseas protection against environmental noise. Sanitary and epidemiological service authorities carry out systematic systematic control over ensuring permissible noise levels in residential and public buildings, as well as on the territory of residential building. At the same time, they are guided by the laws of Ukraine "On the Protection of the Environmental Environment", "Basics of Ukraine's legislation on health care", "On providing sanitary and epidemic well-being", "On the protection of atmospheric air" and others. Control over the noise regime should be carried out in areas of urban territory And in the premises of buildings in which noise levels are normalized.

The work plan of acoustic groups, laboratories or hygienist doctor, which entrusted control over the level of urban and housing and communal noise, it is necessary to include measures to actively identify the sources of noise in residential development and the preparation of card files or passports to these sources indicating in special graphs of such parameters: noise level determined on the basis of insformed measurements or technical documentation; the sphere of propagation of the effect of noise on the population (residential building, therapeutic and preventive institution, school, etc.); The number of people on which the source noise affects; recommendations of the sanitary and epidemiological service; planned activities and timing of their implementation; Efficiency of events.

It is necessary to draw up the sources of the sources of noise of industrial enterprises, transport facilities, transformer substations, service facilities, trade and catering, built into residential buildings, etc.

The tasks of the sanitary and epidemiological service include: the establishment of the reasons for the formation of elevated noise levels, identifying cases of violation of sanitary standards of permissible levels, presenting requirements to eliminate violations of the noise regime, drawing up action plans and control over their implementation.

With an unreasonable delay in conducting measures to weaken the noise or disruption of their fulfillment of their implementation, the sanitary and epidemiological service authorities should apply the appropriate sanctions for the guilty, as well as to make a question for consideration of local governments.

During the implementation of the construction of buildings, the hygienists should control: the implementation of project decisions to ensure the proper sound insulation of the enclosing structures; performing work on vibration and sound insulation during the installation of sanitary and engineering installations and engineering equipment of buildings; quality of construction work. Increased requirements must be made to embedded or additives to residential buildings facilities and enterprises for servicing the population.

Taking part in the work of state commissions on the acceptance of residential and public buildings, sanitary doctors should require documentation on the results of instrumental measurements of noise levels or measure their measurement. When identifying noise levels exceeding sanitary standards, the building cannot be commissioned until the causes of noise formation.

Noise regime in new areas, undoubtedly depends on the quality of preventive sanitary supervision. At the same time, special attention should be paid to the choice of the most favorable areas for the acoustic regime for the construction of residential buildings, medical and preventive, pre-school institutions and schools; placement of recreation places; establishing proper territorial gaps between residential building and noise sources; The rational tracing of roads, streets and travel, etc. All of these issues should be solved together with architects, urban planners, construction institutions of a technical profile. When considering the project documentation, the hygienist doctors are obliged to require acoustic calculations of the expected noise regime and the reasonable choice of measures to ensure that noise levels in neighborhoods, residential and public buildings are not exceeding normative.

The duties of hygienist doctors include: consideration of complaints of the population on the adverse effects of various sources of external and internal noise, measuring sound levels and comparing them with current standards, as well as the presentation of requirements for eliminating the causes of excessive noise formation to organizations and departments, noise sources are located in whose conduct.

Hygienist doctors together with project organizations and technical professional institutions should take part in the compilation of noise maps of the street road network, residential areas, industrial areas at this stage and the prospect. Sanitary and epidemiological service should play a leading role in the work of republican, regional, regional, urban interdepartmental commissions to combat noise, consider issues of the activities of individual institutions, departments and ministries regarding the weakening of the noise of transport, industrial enterprises, equipment, etc.

As shown above, the increasing adverse effect of noise on the human body has significant socio-hygienic and economic consequences, therefore the problem of the fight against noise is acquiring an important nationwide value.

The basis of all legal, organizational and technical measures to reduce production noise is the hygienic rationing of its parameters, taking into account the influence on the body.

It should be noted that the Soviet hygienists have a priority in the development of principles, methods and criteria of the hygienic rationing of noise. In the Soviet Union, for the first time in the world, sanitary standards were introduced and the rules for the limitation of noise in production. They were developed in the Leningrad Institute for Labor Protection of the WCSPS and approved by the heads of the USSR in 1956 (CH-205-56).

Currently, the Soviet Union has "sanitary standards of permissible noise levels" No. 3223 - 85.

In addition to these sanitary standards, in the USSR there is a system of labor safety standards (SSBT) for noise, the appointment of which is to bring the noise characteristics of the manufactured machines in accordance with the noise requirements in the workplaces.

The fundamental GOST of this series for the noise factor is GOSTS PRSBT 12.1.003 - 83, which corresponds to the permissible noise values \u200b\u200bof the SEA 1930 - 79 standard. In addition, the requirements for the noise characteristics of the machines (in the values \u200b\u200bof sound power) are determined by GOST 12.1.023 - 80 " SSBT Noise. Method for establishing noise characteristics of stationary machines »and other standards, as well as standards for machines and equipment of specific species. There are construction standards and rules (SNiP) No. P-12-77 "Noise Protection" and some other regulatory documents.

Soviet hygienists believe that the technical achievability of requirements for machines generating noise must be addressed to noise levels that provide health, in connection with which GOST 12.1.003 - 83 should be applied with the requirements of sanitary standards.

To establish the compliance of the noise characteristics of the issued machines, the requirements for noise levels in the workplace (in the values \u200b\u200bof sound pressure) was developed by GOST 12.1.050 - 86 "SSBT. Methods for measuring noise at workplaces. "

Sanitary standards establish noise classification; Characteristics and permissible noise levels at workplaces; General requirements for measuring normalized values; The main measures to prevent the adverse effects of noise on working.

With hygienic assessment of noise, according to sanitary standards, classified according to 2 principles - the nature of the spectrum and in temporary characteristics.

By the nature of the spectrum of noises are divided into:

Broadband, with a continuous spectrum of more than one octave width;

Tonal, in the spectrum of which there are pronounced discrete tones. The tonal nature of noise for practical purposes (when controlling its parameters in the workplaces) is set by the measurement in the third-rigging bands of the frequency frequencies in one strip above the adjacent no less than 10 dB.

By temporary characteristics of the noise are divided into:

Permanent, the sound level of which for an 8-hour working day (working shift) varies in time by no more than 5 dB (A) when measuring the time characteristic of the "slow" noiseomer;

Non-permanent, whose sound level for an 8-hour working day (working shift) varies in time by more than 5 dB (a) when measured on the temporal characteristic of the "slow" noiseomer.

Non-permanent noises are divided in turn on:

Fluctant in time, the sound level of which continuously changes in time;

Intermittent, the 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;

Pulse, consisting of one or more sound signals, each duration less than 1 s, with sound levels in dB (AI) and dB (A), measured according to the temporal characteristics of the "pulse" and "slowly" noiseomer, differ at least 7 dB (noiseomers must respond to GOST 17187 - 81).

As the characteristics of constant noise at workplaces, as well as to determine the effectiveness of measures to limit its adverse effects, levels of sound pressures in decibels in octave bands with medium-meter frequencies 31.5 are taken; 63; 125; 250; 1000; 2000; 4000 and 8000 Hz.

As a single-numerical characteristic of noise at workplaces, an assessment of the sound level in dB (A) is used (measured on the time characteristic "slowly" noiseomer), which are the weighted average value of the frequency characteristics of sound pressure, taking into account biological action.

The characteristic of non-permanent noise in the workplace is the integral parameter - the equivalent sound level in dB (A). It is allowed as a characteristic of non-permanent noise to use a noise dose or a relative dose of noise.

The concept of "equivalent level of noise" expresses the level of level for a certain time (with hygienic rationing in the USSR - 8 h), averaged according to the rule of equal energy.

The exposition E (or noise dose - ds) defines the quantitative characteristic of noise during its action (cumulation of noise effect).

The exposition is determined in Pa 2 h (1 Pa 2 h \u003d 3.6 * 10 3 Pa 2 C).

Permissible levels of sound pressure in octave bands, sound levels and equivalent levels of sound for workplaces in industrial premises and on the territory of the enterprise for broadband constant and non-permanent (except impulse) noise are presented in Table. eight.

For tonal and impulse noise they should be 5 dB less valuesspecified in the table.

For fluctuating in time and intermittent noise, the maximum sound level should not exceed 110 dB (A).

For pulse noise, the maximum sound level should not exceed 125 dB (AI).

1. The equivalent sound level is determined in accordance with the "methodological instructions for measuring and hygienic evaluation of noise at workplaces" No. 1844-78.

2. The dose of noise or the relative dose is established by "Methodical recommendations for a dose assessment of production noise" No. 2908-82.

Table 8. Permissible sound pressure levels, sound levels and equivalent sound levels on workplaces in industrial premises and in the enterprise

Note. The equivalent level of 85 dBA corresponds to the value of the 8-hour exposure 1 Pa 2 h. The equivalent level of 80 dBA approximately corresponds to the value of the 8-hour exposure 1 * 10 3 Pa 2 C,

Both documents approved the Ministry of Health of the USSR.

The existing sanitary standards are prohibited from staying working in areas with sound pressure levels over 135 dB in any octave strip.

Noise-combination of sounds of various intensity and frequency. Any noise is characterized by sound pressure, sound intensity level, sound pressure level, noise frequency composition.

Sound. pressure- DOP. The pressure arising in the medium during the passage of sound waves (PA). The intensity of sound-number sound. Energy in the enemy of time, passing a h / s cell area, perpendicular to the propagation of sound wave, (W \\ sq..) Sound intensity associated with sound. Susopt pressure. where - through-mean value sound. Pressure in this T-ke sound. Fields, ρ - air density, CT \\ m cubic meter., S-speed sound in the air, m / s. Level of intensity ZV., DB, where - intensity of the star. , corresponding. Threshold audible, W \\ m square. at a frequency of 1000 Hz. The magnitude of the sound. Pressure, dB. , P \u003d 2 * PA -OPLY value of audibility at a frequency of 1000 Hz.

The frequency composition of noise. Spectrum- dependence of the sound levels. Pressures from medium meterometric frequencies 63, 125, 250, 500, 1000, 2000, 4000, 8000 Hz., In the eight-fiber stripes of these frequencies. Octave- Frequencies, in thumb The boundary frequency is twice the lower boundary. Frequencies. The noise depending on the Har ray of the spectrum may be: low- (for 300 Hz), medium- (300-800 Hz), high-frequency (over 800 Hz).

The study in vibroaccoustics shows that the effect of noise on the human body can be divided into 5 steps. At the same time, each stage will be characterized by its sound pressure level.

1 resume - complete absence of noise, which is characteristic of zero pressure level. Such a state is continuous for humans and is very dangerous from a psychological point of view.

2 Sound pressure level reached. up to 40 dB. As a rule, within the regulatory. Sign Such a comp. Yawl. Optimal.

3 The level of sound pressure is adjusted to 75db-region of psychol. The effects of noise at the human org-m. In this case, if the noise sources are uncontrollable, then the monotonous depressing effect on the psyche occurs, fatigue, pressure, heads increase. Pain.

4 - 120 dB. Area psychologist. and physiologist. Action on the body, sustainability heads. Baboral, raise Pressure, first signs of deafness.

5- area injury. The actions of noise, the cat is characteristic of noise level of more than 120 dB.

Noise moves to PRS and 1M-135 dB.

At noise level, more than 170 dB-occurs death.

44) The main methods of combating noise. Sound absorption: scope.

If we consider the noise, a single source is the outer source, then you can determine the intensity of this noise.

I \u003d p * F / B * S, W / m square.

To obtain noise levels in calculating. The point is necessary to proloimnifable, the above is the equation. At the same time, the decree is declared to the threshold (single.) Sign. and introducing 10 lg. L \u003d 10 LG P / Pound +10 LG F / Flas - 10 LG B - 10 LG S / Sound \u003d 1m square.

L \u003d Lp + Mon-B * LP-10 LG S

T. O. From the village of Vyr-I can see that the main ms will reduce the noise level M.B.

· Long-e-ul-nya sound of the noise source, which is a won by the definition of a definition of a constructor and appliances, machines, equip

· Neuh-Mo teaches a poky, for example, (Mon), especially when placing instruments, Oror

· Rapid up to East

Lower noise on the paths of its distribution. At the same time, the introduction of the Special Solution to the creation of obstacles on the way the prison is noise (soundproof-π, fence, walls), and the Spec-e-e-e-conster-E Consp - and, noise silencers.

Sound-absorbing materials are called materials and structures that can absorb the energy of the air sound falling on them. This is usually constructions consisting of porous materials. They are used either in the form of facing of the inner surfaces of the premises, or in the form of independent structures - piece absorbers, usually suspended to the ceiling. Paper absorbers also use drapery, soft chairs, etc.

With friction of the oscillating air particles in the pores, the energy of sound waves goes into heat. The surface of the sound-absorbing cladding is characterized by the sound absorption coefficient A equal to the ratio of the intensity of the absorbed sound to the intensity of the incident

The sound absorption coefficient depends on the type of material, its thickness, porosity, grain size or diameter of the fibers, the presence of the air gap material and its width, frequency and angle of the sound of the sound, the size of sound-absorbing structures, etc. For the open window α \u003d 1 at all frequencies. Sound absorption of the surface of the fence BUTin square meters at this frequency, they call the product of the fencing area s onto its sound absorption coefficient

The sound absorption of the room is consisted of the sum of sound absorption of surfaces and sound absorption BUT )piece absorbers

where p- number of surfaces; t -number of piece absorbers.

Permanent INrooms are called magnitude

B \u003d A POM / (1-)

where - the average sound absorption coefficient constituting

Usually it is assumed that the sound power of the noise source does not change after the device of sound-absorbing structures. Therefore, the effect of reducing noise sound-absorbing cladding in decibels is determined away from the source of noise in the reflected sound field by the formula

where In and in 2 -permanent premises, respectively, before and after the implementation of acoustic measures.

The required reduction in the sound pressure level can be provided by the use of only sound-absorbing structures, if at the calculated points in the reflected sound field this decrease does not exceed 10-12 dB, and at the calculated points at workplaces 4 to 5 dB. In cases where, according to the calculation, a greater decrease is necessary, in addition to sound-absorbing structures, additional means of protection against noise are provided.

45-46) Action electric current on the body. To factors that increase the danger of electric. current can be attributed: widespread; It does not have external signs; Specifies on important components of people (heart, breathing, brain). With certain values, it may cause an inconsistent effect. Types of ELT action on the body: Mechanical; thermal (CRT burns); biological (destruction of alive fabrics and cells); Chemical (blood electrolysis). Types of defeats of the ELT: Local ELT injuries (CRT burns); general defeat The body (CRT strikes). The degree of lesion in many cases depends on a number of factors, i.e. Ultimately wears probabilistic nature. The factors affecting the degree of damage can be attributed: 1. The value of the current flowing through the body of the person at the time of the defeat. Defining. As the degree of lesion of ODA. In responses of the body. Guests are valid - add. Sign Currents and tensions, cat. ORD. 3 Electrical safety criteria for the current force of the current. on the person of the person: the sensations of the sensation (for 50 Hz) ,; The thresholds of non-conscious currents.

2. Rod CRT and AC frequency. As showing. Studies under U.<=500В пост. и переем. токи по разному действ. на сост. организма. Более опасным явл. переем. ток, кот. при меньшем напр. может приводить к более тяжелым последствиям. Наоб. опасной частотой для переем тока явл. 50 Гц.

3. The resistance of the body of the person. El. Sopir. The body of a person is not to yawl. fast. The value and may vary even during the day. The outer layer of the skin has more sopolls, but in Kach. The calculated value of the Rump. The body of a person by the action of CRT. \u003d oh active resistance r \u003d 10 (3) ohm.

4. Path of current flow in the body. In some cases, the degree of progress. Chel-ka ELT depends on how the person relates to the current parts. Naib Hazardous cases are touched. Yawl. "Hand-hand." 5. Duration of the action of the CRT. Decisive can also be: high ref. humidity; High. pace.; The presence at the object of the current. Dust - toko insulation. 6. Status of the OCP. Environments and equipment. In the present Time is the rule of an alternating device from the point of view of elbesecopery of mouth. sl. Room types: Dry; Normal (no high. wet. and high. Temp); wet (75-60%); raw\u003e 75%; especially raw; Hot rooms +30 or more.