The main physical parameters characterizing sound are sound pressure P and sound intensity I. The human hearing aid responds to a value proportional to the mean square of sound pressure

Where P(t)- the difference between the instantaneous values ​​of the total pressure and the average pressure in the medium in the absence of a sound field;

T− averaging time, which for the human ear is in the range of 30-100 ms.

When a sound wave propagates, energy transfer occurs. Sound intensity is the amount of sound energy transferred by a sound wave per unit time through a unit surface area.

Sound pressure is measured in pascals (Pa = 1 N/m2), and sound intensity is measured in W/m2.

Sound intensity is related to sound pressure as follows:

Where ρ − density of the medium, kg/m 3 ; C is the speed of sound, m/s.

The range of audibility of sounds is limited not only to certain frequencies, but also to certain values ​​of pressure and sound intensity. The maximum and minimum sound pressures perceived by humans as sound are called threshold. The minimum values ​​(threshold of audibility) correspond to barely perceptible sounds and at a frequency of 1000 Hz are equal to P o =2*10 -5 Pa, I 0 =10 -12 W/m 2.

The maximum values ​​(threshold of pain) correspond to sounds that cause painful sensations in the hearing organs and at a frequency of 1000 Hz are equal to P b = 2 * 10 2 Pa and I b = 10 2 W/m 2. Thus, the values ​​of sound pressure and sound intensity that a person can distinguish can vary over a wide range: in pressure up to 10 7 times, in intensity up to 10 14 times. Due to the fact that, according to the Weber-Fechner law, the irritating effect of noise on a person is proportional not to the square of the sound pressure, but to the logarithm of it, logarithmic values ​​were introduced - sound pressure levels and intensity, measured in decibels (dB). Bel is a logarithmic unit of the ratio of two quantities (decimal logarithm of the ratio of 2 physical quantities of the same name, for example, powers, currents, sound pressure), 0.1 fraction of Bel is a decibel. 1B = 10dB.

, dB,

Where L– sound pressure level, dB; I 0 And R o- sound intensity and sound pressure corresponding to the hearing threshold at a frequency of 1000 Hz.

The human hearing aid has unequal sensitivity to sounds of different frequencies: the greatest sensitivity is at medium and high frequencies (800-4000 Hz) and the least at low frequencies (20-100 Hz).

Loudness is a subjective sensation that allows the auditory system to rank sounds on a scale from low-intensity sounds ("quiet" sounds) to high-intensity sounds ("loud" sounds).

Sound levels within a 1 Hz band are called spectral density. The dependence of sound levels on frequency is called the noise spectrum

Sounds that are equal in intensity but different in frequency are perceived as sounds of different volumes. Under equal conditions of exposure to noise, the most irritating effect is exerted by noise in the frequency range of 3000-5000 Hz. Therefore, for the physiological assessment of noise, equal loudness curves are used (Fig. 1), which make it possible to judge which sound is subjectively stronger or weaker, and the concept of sound volume level is introduced, the unit of measurement of which is the background. At a frequency of 1000 Hz, the volume levels are assumed to be equal to the sound pressure levels, therefore, 1 background is the sound volume level for which the sound pressure level of an equally loud sound at this frequency is 1 dB.

Fig.1. Equal loudness curves and the dependence of the sound pressure level in dB on frequency at a given volume in the backgrounds

When measuring noise, in order to bring the results of objective measurements closer to subjective perception, they use adjusted sound pressure level (intensity level). The correction consists of introducing corrections to the level of the corresponding quantity depending on the sound frequency (by correcting the frequency response of the sound level meter). These amendments are standardized internationally.

The most common correction is A. Corrected sound pressure level

L A = L−∆L A called sound level and is measured in dBA.

The standard correction value is given below:

Frequency, Hz 16 31.5 63 125 250 500 1000 2000 4000 8000

Correction L A, dB 80 42 26.3 16.1 8.6 3.2 0 -1.2 -1.0 -

NOISE CLASSIFICATION

According to GOST 12.1.003-83, noise is classified according to spectral and temporal characteristics.

By nature of the spectrum noise is divided into:

· broadband with a continuous spectrum more than one octave wide (here it is necessary to provide a definition: an octave is a musical interval in which the ratio of frequencies between sounds is 1 to 2, that is, for an octave, the upper frequency is twice as high as the lower one. Subjectively, by ear, the octave is perceived as stable, basic musical interval: two successive sounds separated by an octave are perceived to be very similar to each other, although they clearly differ in pitch);

· tonal, in the spectrum of which there are pronounced discrete tones. The tonal character of the noise, for practical purposes, is established by measuring in third-octave units (for a third-octave fв/fн= ) frequency bands based on the excess of the sound pressure level in one band over neighboring bands by at least 10 dB. For example, the noise of a circular saw is tonal, while the noise of a jet engine is broadband.

By timing characteristics noise is divided into:

· constant, the sound level of which changes over time by no more than 5 dBA over an 8-hour working day;

· unstable, the sound level of which changes over time by more than 5 dBA over an 8-hour working day.

In turn, intermittent noise is divided into:

· fluctuating in time, the sound level of which continuously changes over time;

· intermittent, the sound level of which changes stepwise (by 5 dBA or 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 lasting less than 1 s.

EFFECT OF NOISE ON HUMANS

The physiological impact of noise on a person depends on many factors: sound pressure level, its frequency composition, exposure time, repetition rate and individual characteristics. Discrete components in the noise spectrum increase the annoyance compared to the original broadband noise. The graph (Fig. 2) shows the zones of noise exposure to a person depending on the sound level and exposure time.

zone I – the use of protective equipment is not required; zones II and III – hearing protection is required; zone IV – the presence of a person with any protection is prohibited

Rice. 2. Typical areas of human exposure to noise

In general, depending on the level and nature of noise, several stages of its impact on a person can be distinguished.

1. There is no noise - the complete absence of noise is unnatural. The absolute silence is depressing. Staying in complete silence for more than a few days leads to mental disorders.

2. Noise 20-60 dBA - background noise that constantly affects a person in everyday activities. The degree of harmfulness of such noise largely depends on the individual attitude towards it. Habitual noise or noise produced by the person himself does not bother him. Noise above 40 dBA can create increased stress on the nervous system, especially during mental work. The impact on the psyche increases with increasing frequency and noise level, as well as with decreasing noise bandwidth,

3. Noise of 60-80 dBA has a psychological effect, creating a significant load on the human nervous system (especially during mental work). As a result, increased fatigue and irritability are observed, attention is weakened, mental reactions slow down, and as a result, productivity and quality of work decrease. With impulsive and irregular noise, the degree of noise exposure increases.

4. Noise of 80-110 dBA has a physiological effect on a person, leading to visible changes in his body. Under the influence of noise above 80 dBA, hearing impairment is observed (decrease in hearing sensitivity primarily at high frequencies).

However, the effect of loud noise on the human body is not characterized only by the state of hearing. Changes in the functional state of the nervous system and a number of organs occur much earlier; their combination is characterized as noise disease. Objective symptoms of noise illness include: decreased hearing sensitivity, changes in digestive function, expressed in decreased acidity, cardiovascular failure, and neuroendocrine disorders. Long-term exposure to noise causes a number of serious diseases associated with overstrain of the nervous system, such as hypertension, and in some cases gastrointestinal and skin diseases.

People working in loud noise environments experience headaches, dizziness, memory loss, and ear pain. A person spends on average 10-20% more physical and neuropsychic effort to maintain the output achieved at a sound level below 70 dBA. All this reduces a person’s performance and safety at work. Labor productivity decreases from noise the more, the more complex the labor process and the more elements of mental labor it contains.

It has been established that during work that requires increased attention, when the sound level increases from 70 to 90 dBA, there is a decrease in labor productivity by 20%.

Increased noise levels lead to an increase in not only occupational, but also general morbidity. This is evidenced by the fact that the overall incidence of illness among workers in noisy industries increased by 15-20%.

5. Noise above 110 dBA has a traumatic effect on the hearing organs. When noise exceeds 140 dBA, the eardrum may rupture.

NOISE CONTROL

The purpose of sanitary regulation is to establish scientifically based maximum permissible noise levels, which, with daily systematic exposure throughout the working day and for many years, do not cause significant changes in a person’s health status and do not interfere with his normal work activity.

In production conditions, in most cases, it is technically very difficult to reduce noise to very low levels, therefore, when standardizing, they proceed not from optimal (comfortable), but from tolerable conditions, i.e. such when the harmful effect of noise on humans does not manifest itself or manifests itself only slightly. Sanitary standards are a compromise between hygienic requirements and technical capabilities at this stage of development of science and technology.

Characteristics and permissible noise levels in workplaces are regulated by GOST 12.l.003-83. "Noise. General safety requirements." The normalized characteristic of constant noise is the sound pressure levels in decibels in octave or 1/3-octave bands with geometric mean frequencies of 63, 125, 250, 500, 1000, 2000, 4000, 8000 Hz. As is known, the geometric mean value f cf for a band with an upper limit frequency f in and bottom f n (for octave band f twice as much f m) is determined by the expression f avg= , for example, if f av =63Hz, then f n =45Hz and f in =90Hz.

The set of permissible sound pressure levels in octave frequency bands is called limiting spectrum, and the specified standardization method is normalization according to the maximum noise spectrum(see Table 1). Limit spectra are designated by the abbreviation PS with a digital index corresponding to the sound pressure level in the octave band with a geometric mean frequency of 1000 Hz. For example, PS-80 denotes the limit spectrum, which has an acceptable sound pressure level of 80 dB in the specified octave band. The values ​​of the maximum permissible sound pressure levels in the standardized octave frequency bands are established taking into account the same physiological and psychological effects of noise on humans.

Table 1

Permissible sound and sound pressure levels in workplaces

Type of work activity, jobs	Sound pressure levels, dB, in octave bands with geometric mean frequencies, Hz	Sound levels and equivalent sound levels, dBA
31,5
Creative activity, leadership work, construction and design, programming, teaching, medical practice
Highly skilled work requiring concentration, administrative and management activities, measurement and analytical work in the laboratory
Workplaces in dispatch service premises, offices and observation and remote control rooms with voice communication by telephone
Workplaces in the driver's cabins of diesel locomotives, electric locomotives, metro trains, diesel trains
Workplaces for drivers and maintenance personnel (passengers) of passenger cars
Workplaces in cockpits and interiors of airplanes and helicopters

Notes to Table 1:

Permissible sound pressure levels in octave frequency bands, sound levels and equivalent sound levels in workplaces should be taken for tonal and impulse noise to be 5 dB less than the values ​​​​indicated in the table;

Even short-term stay in areas with octave sound pressure levels above 135 dB in any octave band is prohibited;

For noise generated in premises by air conditioning, ventilation and air heating installations - 5 dB less than the actual noise levels in these premises (measured or determined by calculation), if the latter do not exceed the values ​​​​specified in the table (correction for tonal and impulse noise in this case should not be accepted), in other cases - 5 dB less than the values ​​​​indicated in the table.

For an approximate assessment (for example, when checking by supervisory authorities, identifying the need for noise reduction measures, etc.) of constant noise in workplaces, it is allowed to use an integral indicator - the sound level in dBA, which is measured by a sound level meter with a corrected frequency response A (along with the linear frequency response , sound level meters have correction A, simulating the nonlinear amplitude-frequency characteristic of the human hearing aid) and is determined by the formula:

P 0- sound pressure corresponding to the hearing threshold (in air P 0 = 2*10 -5 Pa). The sound level is related to the limiting spectrum by the dependence:

L A = PS + 5dB.

A characteristic of non-constant noise is the equivalent (energy) sound level in dBA - the sound level of constant broadband noise, which has the same root-mean-square sound pressure (has the same effect on a person) as this non-constant noise, determined by the formula:

Where P A (t)– current root-mean-square value of sound pressure taking into account sound level meter correction A, Pa; T- duration of noise.

The equivalent level is measured by integrating sound level meters and can be determined by calculation. The essence of the method is that the range to be measured for sound levels is divided into intervals, then at equal intervals over a certain period the sound level is measured on the A scale of the sound level meter and the number of readings in each interval is counted.

Permissible noise levels for various types of work activities according to GOST 12.1.003-83 are given in Table 2.

table 2

Noise levels for different types of work activities

taking into account the degree of labor intensity

“Noise” is a disorderly mixture of sounds.

Low and high frequency sounds seem quieter than mid frequency sounds of the same intensity. Taking this into account, the uneven sensitivity of the human ear to sounds of different frequencies is modulated using a special electronic frequency filter, obtaining, as a result of normalization of measurements, the so-called equivalent (energy-weighted) sound level with the dimension dBA (dB(A), then yes - with filter "A").

A person, in the daytime, can hear sounds with a volume of deB and higher. The maximum frequency range for the human ear is, on average, from 20 to Hz (possible range of values: from to 00 hertz). In youth, mid-frequency sound with a frequency of 3 KHz is better heard, in middle age - 2-3 KHz, in old age - 1 KHz. Such frequencies, in the first kilohertz (up to Hz - the zone of speech communication) - are common in telephones and on radios in the NE and LW bands. With age, the auditory range of sounds narrows: for high-frequency sounds - decreasing to 18 kilohertz or less (in older people, every ten years - by about 1000 Hz), and for low-frequency sounds - increasing from 20 Hz or more.

In a sleeping person, the main source of sensory information about the environment is the ears ("sensitive sleep"). The sensitivity of hearing, at night and with eyes closed, increases aboveB (up to the first decibels, on the dBA scale), compared to the daytime, therefore, loud, sharp noise with large jumps in volume can wake up sleeping people.

Free legal advice:

(SNiP3 “Noise Protection”).

moredeath (noise weapon)

Free legal advice:

The maximum permissible sound levels (LAmax, dBA) are 15 decibels more than “normal”. For example, for living rooms of apartments, the permissible constant sound level during the daytime is 40 decibels, and the temporary maximum is 55. With constantly operating engineering equipment, an amendment of minus 5 is taken into account.

Inaudible noise- sounds with frequencies less than Hz (infrasound) and more than 20 kHz (ultrasound). Low-frequency vibrations of 5-10 hertz can cause resonance, vibration of internal organs and affect brain function. Low-frequency acoustic vibrations increase aching pain in bones and joints in sick people. Infrasound sources: cars, carriages, thunder from lightning, etc.

At workplaces maximum permissible, by law, equivalent sound levels for intermittent noise: the maximum sound level should not exceed 110 dBA, and for impulse noise, mdBAI. It is prohibited to stay even briefly in areas with sound pressure levels above 135 dB in any octave band.

For fire alarm: the sound pressure level of the useful audio signal provided by the siren must be at least 75 dBA at a distance of 3 m from the siren and no more than 120 dBA at any point in the protected room (clause 3.14 of the airbag).

Free legal advice:

Free legal advice:

A device is used to measure noise levels sound level meter(pictured), which is produced in different modifications: household (approximate price, measurement ranges: dB, 31.5 Hz - 8 kHz, filters A and C), industrial (integrating, etc.) The most common models: SL, octave, svan. To measure infrasonic and ultrasonic noise, wide-range noise meters are used.

Sound frequency ranges

mid-frequency0 Hz;

Free legal advice:

Free legal advice:

sand dry / wet0 /

The range of sound propagation along the surface of the earth is reduced by high obstacles (mountains, buildings and structures), the opposite direction of the wind and its speed, as well as other factors (low atmospheric pressure, increased temperature and humidity). Distances at which the source of loud noise is almost inaudible - usually from 100 meters (in the presence of high barriers or in a dense forest), house. - in open areas (with a fair average wind - the range increases to a kilometer or more). With distance, higher frequencies are “lost” (absorbed and dissipated faster) and low-frequency sounds remain. The maximum propagation range of medium-intensity infrasound (a person cannot hear it, but there is an effect on the body) is tens and hundreds of kilometers from the source.

The noisiest cities in Russia

These are many regional and district centers of the country, almost all areas of major transport hubs and urban residential areas along avenues and near airports. This category includes: Moscow, St. Petersburg, Krasnoyarsk, Rostov-on-Don, Chelyabinsk, Yekaterinburg, Perm, Irkutsk, Yaroslavl, Voronezh, Novokuznetsk, Nizhny Tagil, Magnitogorsk, Omsk, Ufa, Samara, Nizhny Novgorod, Novosibirsk, Murmansk , Perm, Tula, Ulyanovsk, Kemerovo and others.

Free legal advice:

When the right and left ears hear sounds (for example, from the player’s headphones, fhertz), the sounds are perceived as being broken down into their original ones, with their actual frequency, and the binary effect disappears. The difference in the phases of sound waves arriving at the right and left ear - allows you to determine the direction to the source of sound / noise, volume and timbre - the distance to it.

International standardization of physical parameters

Free legal advice:

The reaction to prolonged and strong noise exposure is “tinnitus” - ringing in the ears, “noise in the head”, which can develop into progressive hearing loss. It is typical for people over 30 years old, with a weakened body, stress, alcohol abuse and smoking. In the simplest case, the cause of ear noise or hearing loss may be a wax plug in the ear, which can be easily removed by a medical specialist (by rinsing or extraction). If the auditory nerve is inflamed, this can be cured, also relatively easily (with medications, acupuncture). Pulsating noise is a more difficult case to treat (possible causes: narrowing of blood vessels due to atherosclerosis or tumors, as well as subluxation of the cervical vertebrae).

To protect your hearing:

In a noisy place, to protect your hearing, use anti-noise soft earplugs, earbuds or headphones (noise reduction is more effective at high sound frequencies). They must be adjusted individually to the ear. In field conditions, they also use flashlight bulbs (they are not for everyone, but they are the right size). In shooting sports, individually molded “active earplugs” with electronic filling are used, at the same price as a telephone. They must be stored in packaging. It is better to choose earplugs made from hypoallergenic polymer that have good SNR (noise reduction) of 30 dB or more. In case of sudden changes in pressure (on an airplane), to equalize it and reduce pain, you need to use special earplugs with micro holes;

Free legal advice:

Techniques commonly used to equalize pressure on both sides of the eardrum: swallowing, yawning, blowing with a closed nose. The Frenzel method is to hold your nostrils and forcefully move your tongue back along the roof of your mouth (when the muscles contract, the nasal cavities and Eustachian tubes will open). When firing a shot, artillerymen open their mouths or cover their ears with the palms of their hands.

Free legal advice:

Sound level meter SL. Household and industrial noise meters.

Noise level - what and how

In the parameters of climate control equipment, the noise level is indicated separately for the outdoor and indoor units. The noise of the indoor unit is caused by the sound of air passing through the fan. Therefore, more expensive air conditioner models, as a rule, have a larger internal unit size compared to more budget ones of similar power. The explanation for this is simple: a similar volume of air passing through a larger fan rotating at a lower speed creates less noise.

The noise of the outdoor unit is primarily caused by the noise of the compressor. Inverter air conditioner models benefit greatly here. Although the noise level of on/off type air conditioners (not inverter) has also decreased significantly recently.

Note: The table is compiled according to manufacturers' data

From the point of view of the human ear, “noise” is a chaotic mixture of sounds that is unfavorable for human perception. The physical characteristic of sound volume is the sound pressure level, in decibels (dB).

Free legal advice:

A decibel is a dimensionless unit used to measure the ratio of certain quantities, in our case the loudness of a sound. It is important to remember that this is not an absolute value, such as a watt or a volt, but a relative one, such as a multiple (“triple increase”) or a percentage, intended to measure the ratio of two other quantities. In this case, unlike percentages or multiplicities, a logarithmic scale is applied to the resulting ratio.

Decibels are widely used in areas of technology where it is necessary to measure quantities that vary over a wide range: in radio engineering, antenna technology, in information transmission systems, automatic regulation and control, in optics, acoustics, etc.

For a better understanding, consider two cases:

1. What happens if you increase the noise level of 25 dB by another 25 dB? Noise with a total intensity of 50 dB? No - after all, when a number doubles, its logarithm increases by

0.3 (accurate to two decimal places). Then, when the sound intensity doubles, the intensity level increases by

Free legal advice:

0.3 white, that is,

3 dB, up to 28 dB. This is true for any intensity level: doubling the sound intensity results in a 3 dB increase in intensity level.

2. How many times does the noise level differ between 20 and 32 dB? If we were dealing with linear growth, then the answer would be simple: 32 / 20 =

1.5 times. This is the mistake most often made by buyers.

Note: Please note the difference between dB and dBA. dBA – acoustic decibel, a unit of measurement of noise level taking into account human perception of sound. When measured in dBA, a doubling of volume roughly corresponds to a 10 dBA increase in noise level. Those. for 25 dBA increase by 25 dBA

Free legal advice:

Low and high frequency sounds seem quieter than mid frequency sounds of the same intensity.

A person, in the daytime, can hear sounds with a volume of 10 - 15 dB and higher. The maximum frequency range for the human ear is on average from 20 to Hz (possible range of values: from 12 to 24 to Hz). In youth, mid-frequency sound with a frequency of 3 kHz is better heard, in middle age 2 - 3 kHz, in old age 1 kHz. Such frequencies, in the first kilohertz (up to 1000 - 3000 Hz zone of speech communication) are common in telephones. With age, the auditory range of sounds narrows: for high-frequency sounds it decreases to 18 kilohertz or less (in older people, every ten years by about 1000 Hz), and for low-frequency sounds it increases from 20 Hz or more.

For a sleeping person, the main source of information about the outside world is the ears. The sensitivity of hearing sharply increases compared to the daytime, so noise that is not noticeable during the day, and especially noise with jumps in volume, can easily wake up sleeping people.

If there are no sound-absorbing materials on the walls of the premises (carpets, special coverings), the sound will be louder due to multiple reflections (echoes) from the walls, ceiling, furniture), which will increase the final noise level by several decibels.

Noise scale (sound levels in dBA - acoustic decibel, a unit of measurement of noise level taking into account human perception of sound)

Free legal advice:

The permissible maximum according to the standards for residential premises at night, from 23 to 7 o'clock.

(SNiP3 “Noise Protection”).

The norm for residential premises during the day, from 7 to 23 hours (SNiP3 “Noise Protection”).

The maximum permissible sound pressure for the player's headphones.

At sound levels above 160 decibels, rupture of eardrums and lungs is possible, more than 200 - death

Free legal advice:

Spoken speech ranges from 45 decibels (dB) to 60 decibels (dB), depending on the volume of the voice;

The maximum permissible sound levels are 15 decibels higher than “normal”. For example, for living rooms of apartments, the permissible constant sound level during the daytime is 40 decibels, and the temporary maximum is 55. When engineering equipment is constantly running, an amendment is taken into account: minus 5.

Inaudible noise - sounds with frequencies less than Hz (infrasound) and more than 20 kHz (ultrasound). Low-frequency vibrations of 5-10 hertz can cause resonance, vibration of internal organs and affect brain function. Low-frequency acoustic vibrations increase aching pain in bones and joints in sick people. Infrasound sources: cars, carriages, thunder from lightning, etc.

How and by what is noise measured?

A sound level meter is used to measure noise levels. Sound level meters are household (measurement ranges 30 - 130 dB, 31.5 Hz - 8 kHz) and industrial. Wide-range sound level meters are used to measure infrasonic and ultrasonic noise.

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

Free legal advice:

Therefore, all modern sound level meters are equipped with correction circuits, thanks to which it is possible to reduce the sensitivity of the sound level meter to low-frequency and very high-frequency sounds and thereby bring the frequency characteristics of the device closer to the properties of the human ear. Typically, the sound level meter contains three correction circuits, designated A, B and C; correction A is most useful; correction B is used only occasionally; and even less often, correction of S.

Most often, the level of domestic and industrial noise is taken equal to the level measured in dB using a sound level meter with correction A, and is expressed in units of dBA. Although the human ear perceives sound incomparably more refined than a sound level meter, and therefore sound levels expressed in dBA by no means correspond exactly to physiological response, the simplicity of this unit makes it extremely convenient for practical use.

Another advantage of the dBA scale is the fact that doubling the volume roughly corresponds to an increase in noise level by 10 dBA.

To approximate the noise level, you can use “available tools” in the form of a desktop computer, laptop, tablet and or smartphone. Of course, such a measurement will be rougher than one performed even with the help of a specialized household sound level meter, but it is practically free.

We measure the noise level using a desktop computer or laptop:

Free legal advice:

• For a PC with MS Windows 8, you can use the free Decibel Meter or Asa Tempo application. They can be downloaded from the Microsoft App Store (https://www.microsoft.com/en-us/store/apps/windows). These applications use a microphone connected to your computer, either external or built-in, and can measure sounds up to 96 dB (Decibel Meter).
• For Apple products there are similar programs in the iTunes App Store (Decibel 10th - Professional Noise Meter).
• You can also use sound editors to measure the volume of noise. The main thing is that the program can work with a microphone as a sound source. For example, Audacity, a free sound editor (GNU GPL v2 license), has a function for measuring the input signal level. It is available for a wide variety of operating systems: MS Windows (10/8/7/Vista/XP), GNU/Linux, Mac OS X. You can download it from the developers’ website at http://www.audacityteam.org/ Users of the OS family GNU/Linux in most cases can install it directly from the repository of their distribution.

For tablet and smartphone:

A microphone in a mobile device will certainly not provide the same quality as an external microphone, but you will have the ability to measure sound levels almost anywhere. Nevertheless, this accuracy will be sufficient to estimate the noise level in most domestic situations.

• For Apple devices: Decibel 10th, Decibel Meter Pro, dB Meter, Sound Level Meter;
• For Android devices: deciBel, Decibel Meter, Noise Meter, Sound Meter;
• For devices running MS Windows Phone: Cyberx Decibel Meter, Decibel Meter Free, Decibel Meter Pro.

What and how does the air conditioner make noise?

1. Compressor. It is also a source of low-frequency (including infra-low, spreading primarily through building structures) noise.

In split systems its contribution is lower than in window or mobile models. Also in mobile and window systems it is combined with fan noise and air flow noise.

2. Indoor unit fan. The motor should not be heard.

3. Swinging sash. If you can hear it, contact service

4. Mode switching relay. Heard on non-inverter (“on/off”) models

Refrigerant noise: you can hear it through the lines only during heating, if you can hear it during cooling, it means there are some problems

What makes noise in heaters and how?

1. In convectors (fan heaters) and heat guns: fans and air flow. The smaller the fan diameter, the greater the noise. The noise level is also affected by the shape of the ventilation grille.
2. In oil coolers - oil movement at high power
3. In gas and diesel heat guns: flame

Hygienic noise standards

To determine the permissible noise level in workplaces, residential premises, public buildings and residential areas, GOST 12.1.003-83 is used. SSBT “Noise. General safety requirements”, SN 2.2.4/2.1.8. “Noise in workplaces, in residential and public buildings and in residential areas.” Sound range noise is rated according to the maximum noise level spectrum and dBA. This method sets maximum permissible levels (MAL) in nine octave bands with geometric mean frequencies of 31, 63, 125, 250, 500, 1000, 2000, 4000, 8000 Hz.

Noise in workplaces, in residential and public buildings and in residential areas

Free legal advice:

About decibels, sound volume. Noise level and its sources

The physical characteristic of sound volume is the sound pressure level, in decibels (dB). “Noise” is a disorderly mixture of sounds.

Low and high frequency sounds seem quieter than mid frequency sounds of the same intensity. Taking this into account, the uneven sensitivity of the human ear to sounds of different frequencies is modulated using a special electronic frequency filter, obtaining, as a result of normalization of measurements, the so-called equivalent (energy-weighted) sound level with the dimension dBA (dB(A), then Yes - with filter “A”).

A person, in the daytime, can hear sounds with a volume of deB and higher. The maximum frequency range for the human ear is, on average, from 20 to Hz (possible range of values: from to 00 hertz). In youth, mid-frequency sound with a frequency of 3 KHz is better heard, in middle age - 2-3 KHz, in old age - 1 KHz. Such frequencies, in the first kilohertz (up to Hz - the zone of speech communication) - are common in telephones and on radios in the NE and LW bands. With age, the auditory range of sounds narrows: for high-frequency sounds - decreasing to 18 kilohertz or less (in older people, every ten years - by about 1000 Hz), and for low-frequency sounds - increasing from 20 Hz or more.

In a sleeping person, the main source of sensory information about the environment is the ears (“sensitive sleep”). The sensitivity of hearing, at night and with eyes closed, increases aboveB (up to the first decibels, on the dBA scale), compared to the daytime, therefore, loud, sharp noise with large jumps in volume can wake up sleeping people.

If there are no sound-absorbing materials (carpets, special coverings) on the walls of the premises, the sound will be louder due to multiple reflections (reverberation, that is, echoes from the walls, ceiling and furniture), which will increase the noise level by several decibels.

Noise scale (sound levels, decibels), in the table

The permissible maximum according to the standards for residential premises at night, from 23 to 7 o'clock.

The norm for residential premises during the day, from 7 to 23 hours.

Maximum permissible sound pressure for the player's headphones (according to European standards)

At sound levels above 160 decibels, rupture of eardrums and lungs is possible,

moredeath (noise weapon)

The maximum permissible sound levels (LAmax, dBA) are 15 decibels more than “normal”. For example, for living rooms of apartments, the permissible constant sound level during the daytime is 40 decibels, and the temporary maximum is 55.

Inaudible noise - sounds with frequencies less than Hz (infrasound) and more than 20 KHz (ultrasound). Low-frequency vibrations of 5-10 hertz can cause resonance, vibration of internal organs and affect brain function. Low-frequency acoustic vibrations increase aching pain in bones and joints in sick people. Infrasound sources: cars, carriages, thunder from lightning, etc.

In workplaces, the maximum permissible, by law, equivalent sound levels for intermittent noise: the maximum sound level should not exceed 110 dBA, and for impulse noise, dBAI. It is prohibited to stay even briefly in areas with sound pressure levels above 135 dB in any octave band.

When constructing buildings and structures in accordance with modern, more stringent sound insulation requirements, technologies and materials must be used that can provide reliable protection from noise.

For fire alarms: the sound pressure level of the useful audio signal provided by the siren must be at least 75 dBA at a distance of 3 m from the siren and no more than 120 dBA at any point in the protected room (clause 3.14 of the airbag).

116 dB(A) - when installing a sound emitter on the roof of a vehicle;

122 dBA - when installing the radiator in the engine compartment of a vehicle.

Fundamental frequency changes should be from 150 to 2000 Hz. Cycle duration is from 0.5 to 6.0 s.

If a city dweller, accustomed to constant noise, finds himself in complete silence for some time (in a dry cave, for example, where the noise level is less than 20 db), then he may well experience depression instead of rest.

Sound meter device for measuring sound level, noise

To measure the noise level, a sound level meter is used (pictured), which is produced in different modifications: household (approximate price, measurement ranges: dB, 31.5 Hz - 8 kHz, filters A and C), industrial (integrating, etc.). d.) The most common models: SL, octave, svan. Wide-range noise meters are used to measure infrasonic and ultrasonic noise.

Sound frequency ranges

Subranges of the audio frequency spectrum to which the filters of two- or three-way speaker systems are tuned: low-frequency - fluctuations up to 400 hertz;

mid-frequency0 Hz;

Speed ​​of sound and range of its propagation

The approximate speed of audible, mid-frequency sound (frequency of the order of 1-2 kHz) and the maximum range of its propagation in various environments:

in the air - 344.4 meters per second (at a temperature of 21.1 Celsius) and approximately 332 m/s - at zero degrees;

in water - approximately 1.5 kilometers per second;

in hard wood - about 4-5 km/s along the fibers and one and a half times less - across.

in stainless steel - 5.8 kilometers per second.

Polystyrene - 2.4 kilometers per second.

sand dry / wet0 /

The range of sound propagation along the surface of the earth is reduced by high obstacles (mountains, buildings and structures), the opposite direction of the wind and its speed, as well as other factors (low atmospheric pressure, increased temperature and humidity). Distances at which the source of loud noise is almost inaudible - usually from 100 meters (in the presence of high barriers or in a dense forest), house. - in open areas (with a fair average wind - the range increases to a kilometer or more). With distance, higher frequencies are “lost” (attenuated and dissipated faster) and low-frequency sounds remain. The maximum propagation range of medium-intensity infrasound (a person cannot hear it, but there is an effect on the body) is tens and hundreds of kilometers from the source.

If during a thunderstorm you saw strong lightning and after 12 seconds heard the first rumbles of thunder, this means that lightning struck four kilometers from you (340 * 12 = 4080 m.) In approximate calculations, it is assumed that three seconds per kilometer of distance (in air space) to the sound source.

Binaural Beat Frequency

When the right and left ears hear sounds (for example, from the player's headphones, f< 1000 герц, f1 - f2 < 25 Гц) двух различных частот - мозг, в результате обработки этих сигналов, получает третью, разностную частоту биения (бинауральный ритм, который равен арифметической разнице их частоты), «слышимую» как низкочастотные колебания, совпадающие с диапазоном обычных мозговых волн (дельта - до 4 Гц, тета - 4-8Гц, альфаГц, бетаГц). Этот биологический эффект учитывается и используется в студиях звукозаписи - для передачи низких частот, не воспроизводимых напрямую динамиками обычных стереосистем (вследствие конструкционных ограничений), но эти способы и методы, при неумелом применении, могут негативно сказаться на психологическом состоянии и настроении слушателя, так как отличаются от естественного, природного восприятия человеческим ухом шумов и звуков.

In those places of the ionosphere where electromagnetic waves of sufficient power hit, with a well-established (with high signal quality) Schumann resonance, especially at the frequencies of its first harmonics, the resulting plasma clots begin to emit infrasonic acoustic (sound) waves. Specific ionospheric emitters exist as long as lightning discharges continue in the initiating thunderstorm source - approximately up to the first tens of minutes. For the eight-hertz frequency, these emitting points are located on the opposite side of the globe from the electromagnetic source. waves On 14 Hz - in a triangle. Local, highly ionized regions in the lower layers of the ionosphere (sporadic Es layer) and plasma reflectors can be interconnected or spatially coincide.

Long-term exposure to noise levels above decibels can lead to partial or complete hearing loss (at concerts, the power of speaker systems can reach tens of kilowatts). Also, pathological changes in the cardiovascular and nervous systems can occur. Only sounds with a volume of up to 35 dB are safe.

The reaction to prolonged and strong noise exposure is “tinnitus” - ringing in the ears, “noise in the head”, which can develop into progressive hearing loss. It is typical for people over 30 years old, with a weakened body, stress, alcohol abuse and smoking. In the simplest case, the cause of ear noise or hearing loss may be a wax plug in the ear, which can be easily removed by a medical specialist (by rinsing or extraction). If the auditory nerve is inflamed, this can be cured, also relatively easily (with medications, acupuncture). Pulsating noise is a more difficult case to treat (possible causes: narrowing of blood vessels due to atherosclerosis or tumors, as well as subluxation of the cervical vertebrae).

To protect your hearing:

Do not increase the sound volume in the player's headphones in an attempt to drown out external noise (in the subway or on the street). At the same time, electromagnetic radiation to the brain from the headphone speaker also increases;

In a noisy place, to protect your hearing, use anti-noise soft earplugs, earbuds or headphones (noise reduction is more effective at high sound frequencies). They must be adjusted individually to the ear. In field conditions, they also use flashlight bulbs (they are not for everyone, but they are the right size). In shooting sports, individually molded “active earplugs” with electronic filling are used, at the same price as a telephone. They must be stored in packaging. It is better to choose earplugs made from hypoallergenic polymer that have good SNR (noise reduction) of 30 dB or more. In case of sudden changes in pressure (on an airplane), to equalize it and reduce pain, you need to use special earplugs with micro holes;

In the premises, use noise-insulating environmentally friendly materials to reduce noise;

When underwater diving, to prevent the eardrum from rupturing, blow in time (blow through the ears by holding your nose or swallowing). Immediately after diving, you cannot board a plane. When jumping with a parachute, you also need to equalize the pressure in a timely manner so as not to get barotrauma. Consequences of barotrauma: noise and ringing in the ears (subjective “tinnitus”), hearing loss, ear pain, nausea and dizziness, and in severe cases, loss of consciousness.

With a cold and runny nose, when the nose and maxillary sinuses are blocked, sudden changes in pressure are unacceptable: diving (hydrostatic pressure - 1 atmosphere per 10 meters of immersion depth in water, that is: two - at ten, three - at around 20 m. and etc.), parachute jumping (0.01 atm per 100 m altitude, increases rapidly, with acceleration).

// approximately seven and a half millimeters of mercury barometer - for every hundred meters, in height.

Give your ears a break from loud noise.

Techniques usually used to equalize pressure on both sides of the eardrum: swallowing, yawning, blowing with a closed nose. When firing a shot, artillerymen open their mouths or cover their ears with the palms of their hands.

Other articles on a similar topic in the left menu “To topic”.

Search

Resources

Resources that are interesting to us and will be useful to you.

Articles topic

Economical construction

Your calculator:

Brands

All rights reserved by the law of the Russian Federation and planet Earth, 2010–2013, ©

Noise level. What does 35 dB mean and what can it be compared to?

The noise characteristics of the equipment are given in the form of tables, which contain:

• Sound power level LWA in dB(A) by frequency band, sound power levels to the input, output and surroundings of the fan.
• Overall sound pressure level dB(A) at a distance of 3m.

The frequency band is divided into 8 wave groups. In each group, the average frequency is determined: 63 Hz, 125 Hz, 250 Hz, 500 Hz, 1000 Hz, 2 kHz, 4 kHz and 8 kHz. Any noise is broken down into frequency groups and the distribution of sound energy over different frequencies can be found.

The noise from the fan spreads through the air duct (air channel), is partially attenuated in its elements and penetrates into the serviced room through the air distribution and air intake grilles.

The basis for the design of ventilation systems is acoustic calculation - a mandatory application to the ventilation project of any facility.

The main tasks of such a calculation are: determination of the octave spectrum of ventilation noise at design points and its required reduction by comparing this spectrum with the permissible spectrum according to hygienic standards. After selecting construction and acoustic measures to ensure the required noise reduction, a verification calculation of the expected sound pressure levels at the same design points is carried out, taking into account the effectiveness of these measures.

Can not hear anything

almost inaudible

quiet rustle of leaves

human whisper (at a distance of 1m).

human whisper (1m)

whispering, ticking of the wall clock.

norm for residential premises at night, from 23 to 7 am

norm for residential premises, from 7 to 23 hours

normal conversation

conversation, typewriter

Standard for class A office premises (according to European standards)

the norm for offices

loud conversation (at a distance of 1m)

loud conversations (1m)

scream, sound of a motorcycle with a muffler

loud scream, sound of a motorcycle with a muffler

loud screams, freight railway car (at a distance of 7 m)

sound of a passing subway car (7m)

the sound of an orchestra, the intermittent sounds of a passing subway car, the sound of thunder

maximum permissible sound pressure for the player's headphones (according to European standards)

Noise- random oscillations of various physical natures, characterized by the complexity of their temporal and spectral structure.

• Originally the word noise referred exclusively to sound vibrations, but in modern science it was extended to other types of vibrations (radio, electricity).

  Noise classification

  Noise- a set of aperiodic sounds of varying intensity and frequency. From a physiological point of view, noise is any unfavorable perceived sound.

  By spectrum

  Noises are divided into stationary and non-stationary.

  By the nature of the spectrum

  Based on the nature of the spectrum, noise is divided into:

• broadband noise with a continuous spectrum more than 1 octave wide;
• tonal noise, in the spectrum of which there are pronounced tones. A tone is considered pronounced if one of the one-third octave frequency bands exceeds the others by at least 7 dB.

By frequency (Hz)

According to the frequency response, noise is divided into:

• low frequency (<400 Гц)
• mid-frequency (400-1000 Hz)
• high frequency (>1000 Hz)

According to time characteristics

• constant;
• unstable, which in turn is divided into oscillating, intermittent and impulsive.

By nature of occurrence

• Mechanical
• Aerodynamic
• Hydraulic
• Electromagnetic

  Noise measurement

  To quantify noise, averaged parameters determined on the basis of statistical laws are used. Sound level meters, frequency analyzers, correlometers, etc. are used to measure noise characteristics.

  Noise levels are most often measured in decibels.

  Sound intensity in decibels

• Conversation: 40-45
• Office: 50-60
• Street: 70-80
• Factory (heavy industry): 70-110
• Chainsaw: 100
• Jet launch: 120
• Vuvuzela: 130

Sources of noise

Sources acoustic noise any vibrations in solid, liquid and gaseous media can serve; In technology, the main sources of noise are various engines and mechanisms. The following classification of noise according to its source is generally accepted: - mechanical; - hydraulic; - aerodynamic; - electric.

Increased noise of machines and mechanisms is often a sign of malfunctions or irrational designs. Sources of noise in production include transport, technological equipment, ventilation systems, pneumatic and hydraulic units, as well as sources that cause vibration.

Non-acoustic noises

Electronic noise- random fluctuations of currents and voltages in radio-electronic devices arise as a result of uneven emission of electrons in electric vacuum devices (shot noise, flicker noise), uneven processes of generation and recombination of charge carriers (conduction electrons and holes) in semiconductor devices, thermal movement of current carriers in conductors (thermal noise), thermal radiation of the Earth and the Earth's atmosphere, as well as planets, the Sun, stars, the interstellar medium, etc. (space noise).

Impact of noise on humans

Noise in the audio range leads to decreased attention and increased errors when performing various types of work. Noise slows down a person's reaction to signals coming from technical devices. Noise depresses the central nervous system (CNS), causes changes in breathing rate and heart rate, contributes to metabolic disorders, the occurrence of cardiovascular diseases, stomach ulcers, and hypertension. When exposed to high levels of noise (more than 140 dB), rupture of the eardrums, contusion, and at even higher levels (more than 160 dB) and death are possible.

Hygienic noise regulation

To determine the permissible noise level in workplaces, residential premises, public buildings and residential areas, GOST 12.1.003-83 is used. SSBT “Noise. General safety requirements”, SN 2.2.4/2.1.8.562-96 “Noise in workplaces, in residential and public buildings and in residential areas.”

Normalization of noise in the audio range is carried out using two methods: according to the maximum noise level spectrum and according to dBA. The first method sets maximum permissible levels (MAL) in nine octave bands with geometric mean frequencies of 63, 125, 250, 500, 1000, 2000, 4000, 8000 Hz. The second method is used to normalize non-constant noise and in cases where the spectrum of real noise is not known. The normalized indicator in this case is the equivalent sound level of broadband constant noise, which has the same impact on a person as real non-constant noise, measured on the A scale of a sound level meter.

Noise colors

Noise colors- a system of terms that assigns certain colors to certain types of noise signals based on the analogy between the spectrum of a signal of an arbitrary nature (more precisely, its spectral density or, mathematically speaking, the distribution parameters of a random process) and the spectra of various colors of visible light. This abstraction is widely used in branches of technology that deal with noise (acoustics, electronics, physics, etc.).

White noise

White noise- stationary noise, the spectral components of which are evenly distributed over the entire range of frequencies involved. Examples of white noise are the noise of a nearby waterfall (distant waterfall noise is pink, since high-frequency components of sound are attenuated in the air more than low-frequency ones), or Schottky noise at high-resistance terminals. It gets its name from white light, which contains electromagnetic waves of frequencies across the entire visible range of electromagnetic radiation.

In nature and technology, “pure” white noise (that is, white noise having the same spectral power at all frequencies) does not occur (due to the fact that such a signal would have infinite power), however, any noise whose spectral density is the same (or slightly different) in the frequency range under consideration.

Statistical properties

The term "white noise" is usually applied to a signal that has an autocorrelation function, mathematically described by the Dirac delta function across all dimensions of the multidimensional space in which the signal is considered. Signals with this property can be considered as white noise. This statistical property is fundamental for signals of this type.

The fact that white noise is uncorrelated in time (or in any other argument) does not determine its values ​​in the time (or any other argument considered) domain. The sets received by the signal can be arbitrary up to the main statistical property (however, the constant component of such a signal must be equal to zero). For example, a binary signal that can only take values ​​equal to zero or one will only be white noise if the sequence of zeros and ones is uncorrelated. Signals that have a continuous distribution (such as a normal distribution) can also be white noise.

Discrete white noise is simply a sequence of independent (that is, statistically unrelated to each other) numbers.

Flicker noise, pink noise

flicker noise (flicker noise, 1/f noise, Sometimes pink noise in the narrow applied understanding of such a term) - electronic noise observed in almost any electronic devices; its sources may be inhomogeneities in the conducting medium, generation and recombination of charge carriers in transistors, etc. Usually mentioned in connection with direct current.

Flicker noise has the spectrum of pink noise, which is why it is sometimes called that. However, one should distinguish between pink noise, as a mathematical model of a signal of a certain type, and flicker noise, as a well-defined phenomenon in electrical circuits.

In 1996, at the Institute of Thermophysics, Ural Branch of the Russian Academy of Sciences, V.P. Koverdoy and V.N. Skokov experimentally discovered intense thermal pulsations during the transition from the bubble boiling regime of liquid nitrogen to the film boiling regime in the thermal region of a high-temperature superconductor. The spectrum of these pulsations corresponds to flicker noise

Red noise

Red noise (Brownian noise) is a noise signal that produces Brownian motion. Because in English it is called Brown (Brownian) noise, its name is often translated into Russian as brown noise.
The spectral density of red noise is proportional to 1/f², where f is the frequency. This means that at low frequencies the noise has more energy, even more than pink noise. The noise energy drops by 6 decibels per octave. Acoustic red noise is heard as muffled compared to white or pink noise

Blue (cyan) noise

Blue noise is a type of signal whose spectral density increases by 3 dB per octave. That is, its spectral density increases with frequency, and, similar to white noise, in practice it must be frequency limited. To the ear, blue noise is perceived as sharper than white noise. Blue noise is obtained by differentiating pink noise; their spectra are mirror-like.

Purple noise

Violet noise is a type of signal whose spectral density increases by 6 dB per octave. That is, its spectral density is proportional to the square of the frequency and, similar to white noise, in practice it must be frequency limited. Violet noise is obtained by differentiating white noise. The spectrum of violet noise is the mirror opposite of the spectrum of red.

Gray noise

Term gray noise refers to a noise signal that has the same subjective loudness to human hearing over the entire range of perceived frequencies. The spectrum of gray noise is obtained by adding the spectra of Brownian and violet noise. In the spectrum of gray noise, a large “dip” is visible at mid-frequencies, but the human ear subjectively perceives gray noise as uniform in spectral density (without a predominance of any frequencies).

The American Federal Telecommunications Standard 1037C Glossary defines white, pink, blue and black noise.

Orange noise

Orange noise is quasi-stationary noise with a finite spectral density. The spectrum of such noise has stripes of zero energy scattered throughout the spectrum. These stripes are located at the frequencies of musical notes.

Red noise

Red noise can be either a synonym for Brownian or pink noise, or a designation for natural noise characteristic of large bodies of water - seas and oceans that absorb high frequencies. Red noise is heard from the shore from distant objects located in the ocean.

Green noise

Green noise is the noise of the natural environment. Similar to pink noise with enhanced frequency region around 500 Hz

Black noise

The term "black noise" has several definitions:

• Silence
• Noise with spectrum 1/f β, where β > 2 (Manfred Schroeder, “ Fractals, chaos, power laws"). Used to simulate various natural processes. Considered to be characteristic of "natural and man-made disasters such as floods, market crashes, etc."
• Ultrasonic white noise (with a frequency of more than 20 kHz), similar to the so-called. "black light" (with frequencies too high to be perceived, but capable of affecting the observer or instruments).
• Noise whose spectrum has predominantly zero energy except for a few peaks

Noise is defined as a disordered combination of different sounds having tones of varying strength and frequency. Noise levels must be measured in quantities capable of expressing the degree of sound pressure produced. Such units of noise level measurement are associated with the names of two physicists - Alexander Bell and Heinrich Hertz.

Bels, or more often decibels, express the relative loudness of a sound. At its core, a decibel is ten times the logarithm of the ratio of the intensity of existing sound energy to its value. It is not directly a unit of measurement, but rather an expression of a relationship.

The measurable characteristic of sound is the amount of energy contained in it. That is, its intensity as a flow of this energy. That is why the quantitative characteristic is, for example, expressed in watts per square meter (W/m2). However, the obtained values ​​relative to the reference level of 10−12 W/m2 are so small and incomprehensible to most ordinary people that 1 bel was “adopted” to express the resulting ratios. For example, the noise level of a jet airplane is about 13 bels, or in smaller units 130 decibels (dB). For the human ear, the normal range of noise is defined by the boundaries from 20 to 120 decibels. At sounds above this level, a person can suffer serious injuries to the eardrum and contusion. And 160 dB can be lethal.

All people experience noise in their homes. They consist of those directly arising in the room and penetrating from the outside. In order to protect the health and normal condition of citizens, standards for permissible penetrating noise have been adopted. This is 40 dB during the day and 30 at night. Average indicators of noise level units prove that in approximately 80% of cases, even with normal operation of the radio and TV, conversations, noise penetrating from neighboring apartments remains at a level of 40-45 dB, and sounds from the entrance (elevator movement, door slams) reach 60 dB.

In addition to sound intensity, the human ear is sensitive to noise vibrations. Hertz is a unit of frequency, equal to the frequency of the ongoing periodic process, in which one cycle of such a periodic process occurs in 1 second (that is, 1 oscillation). Therefore, for an objective characterization it is necessary to use both of these units of noise level measurement. The human hearing system is more sensitive to vibrations created by high frequencies than by low frequencies. But in industrial and living conditions, everyone is under the influence of the entire spectrum. In this regard, when comparing the sound volume level, it is necessary, in addition to the characteristics of the strength and intensity of the sound in decibels, to also indicate the frequency of vibrations per second.

Noise unit

Noise levels are measured in units expressing the degree of sound pressure. They are associated with the names of two famous scientists - A.G. Bell, inventor of the telephone, and Heinrich Hertz, German physicist. In bels, or more commonly, decibels, the relative loudness of a sound is measured. A decibel is ten times the logarithm of the ratio of the intensity of sound energy to its value. Sound is also measured in Hertz. Hz is an SI unit of frequency equal to the frequency of a periodic process, in which one cycle of the periodic process occurs in 1 second (for example, 1 oscillation). But who determines when noise is harmful and when it is not? - The person himself, since the human ear is “the most accurate measuring instrument.”

The fact is that the human ear has an extremely large sensitivity range - from 20 dB to 120 dB, which corresponds to 10 times the energy.

Types of noise

There are noises: industrial and non-industrial.

There are also favorable noises:

Sound of the surf

The murmur of a spring

rustling leaves

These sounds are always pleasant to a person. They calm him down and relieve stress.

Environmental regulation of parametric pollution

The concept of environmental regulation

Ecological regulation is the regulation of anthropogenic impact on an ecosystem within the limits of its ecological capacity, which does not lead to disruption of self-regulation mechanisms. The main criteria for environmental regulation are: maintaining biotic balance, stability and diversity of the ecosystem.

In environmental practice in Russia, as well as throughout the world, environmental regulation is used as one of the main measures or tools for environmental protection.

The development and adoption of environmental standards is one of the areas of environmental protection activities of authorized government bodies.

The development of environmental regulation is intended to ensure the creation of a system of real guidelines for minimizing anthropogenic impact, reflecting fundamental natural processes and the capabilities of modern technologies.

Standardized parameters and maximum permissible noise levels in workplaces

Characteristics of constant noise in workplaces are sound pressure levels in octave bands with geometric mean frequencies of 31.5; 63; 125; 250; 500; 1000; 2000; 4000; 8000 Hz, determined by the formula:

L = 201gР/Р0, where

P - root mean square sound pressure, Pa;

Po - the initial value of sound pressure in air equal to 2-10°Pa.

It is allowed to take the sound level in dBA as a characteristic of constant broadband noise in workplaces, measured on the time characteristic of a “slow” sound level meter, determined by the formula:

LA = 201g RA / P0,

where PA is the root-mean-square value of sound pressure taking into account the correction “A” of the sound level meter, Pa.

A characteristic of non-constant noise in workplaces is the equivalent (energy) sound level in dBA.

Maximum permissible sound levels and equivalent sound levels at workplaces, taking into account the intensity and severity of work activity, are presented in Table.

Quantitative assessment of the severity and intensity of the labor process should be carried out in accordance with Guideline 2.2.013-94 “Hygienic criteria for assessing working conditions in terms of harmfulness and danger of factors in the working environment, severity, intensity of the labor process.”

Maximum permissible sound levels and equivalent sound levels at workplaces for work activities of different categories of severity and intensity in dBA

Notes:

* for tonal and impulse noise, the remote control level is 5 dBA less than the values ​​​​indicated in the table. 1;

* for noise generated indoors by air conditioning, ventilation and air heating installations - 5 dBA less than the actual noise levels in the premises (measured or calculated), if the latter do not exceed the values ​​​​of the table. 1 (correction for tonal and impulse noise is not taken into account), otherwise - 5 dBA less than the values ​​​​indicated in table. 1;

* additionally, for time-varying and intermittent noise, the maximum sound level should not exceed 110 dBA, and for impulse noise -125 dBA1.

The maximum permissible sound pressure levels in octave frequency bands, sound levels and equivalent sound levels for the main most typical types of work activities and jobs, developed taking into account the categories of severity and intensity of work, are presented in Table. 2.

Acceptable sound pressure levels in octave frequency bands, sound levels and equivalent sound levels