penetrating noise: noise that occurs outside a given room and penetrates into it through building envelopes, ventilation, water supply and heating systems.

constant noise: noise, the sound level of which changes over time by no more than 5 dBA when measured on the “slow” time characteristic of the sound level meter according to GOST 17187.

Intermittent noise: noise, the sound level of which changes over time by more than 5 dBA when measured on the “slow” time characteristic of the sound level meter according to GOST 17187.

tonal noise: Noise whose spectrum contains audible discrete tones. The tonal nature of the noise is determined by measuring in one-third octave frequency bands by exceeding the level in one band over the neighboring ones by at least 10 dB.

impulse noise: intermittent noise consisting of one or a series of sound signals(pulses), the sound levels of which (of which), measured in dBAI and dBA, respectively, on the time characteristics of the "impulse" and "slow" sound level meter according to GOST 17187, differ from each other by 7 dBA or more.

Sound pressure level: ten times the base 10 logarithm of the ratio of the square of the sound pressure to the square of the threshold sound pressure (Po = 2*10 -5 Pa) in dB.

Octave sound pressure level: sound pressure level in octave band in dB.

Sound level: noise sound pressure level in the normalized frequency range, corrected according to the frequency response A of the sound level meter according to GOST 17187 in dBA.

Equivalent (energy) sound level: the sound level of a constant noise that has the same RMS sound pressure value as the intermittent noise under investigation during a specified time interval in dBA.

Maximum sound level: the sound level of intermittent noise corresponding to the maximum reading of a measuring, direct-reading instrument (sound level meter) during a visual reading, or the sound level exceeded for 1% of the duration of the measuring interval when noise is recorded by an automatic evaluating device (statistical analyzer).

Impact sound insulation: value characterizing the reduction of impact sound by overlapping.

Airborne sound insulation (sound insulation) R: the ability of a building envelope to reduce sound passing through it. In general terms, it is a tenfold decimal logarithm of the ratio of the sound energy incident on the fence to the energy passing through the fence. In this document, airborne sound insulation refers to the airborne sound insulation provided by the room separating two rooms.
reduction of sound pressure levels in dB, reduced to the conditions of equality of the area of ​​the enclosing structure and the equivalent area of ​​sound absorption in the protected room
R = L1-L2 + 10lg(S/A),

where L1 is the sound pressure level in the room with the sound source, dB; L2 - sound pressure level in the protected room, dB; S - area of ​​the enclosing structure, m2; A is the equivalent sound absorption area in the protected room, m2.

Reduced impact noise level under floor Ln: value that characterizes the impact noise insulation by the ceiling (represents the sound pressure level in the room under the ceiling when working on the floor of a standard impact machine), conditionally reduced to the equivalent sound absorption area in the room Ao = 10 m2. A standard percussion machine has five hammers weighing 0.5 kg each, falling from a height of 4 cm at a frequency of 10 beats per second.

Airborne noise isolation frequency response: airborne sound insulation value R, dB, in one-third octave frequency bands in the range 100-3150 Hz (in graphical or tabular form).

Frequency response of the reduced level of impact noise under the ceiling: the value of the reduced levels of impact noise under the ceiling Ln, dB, in one-third octave frequency bands in the range of 100-3150 Hz (in graphical or tabular form).

Airborne sound insulation index Rw: a value used to evaluate the soundproofing ability of a fence with a single number. Determined by comparing the frequency response of the airborne sound insulation to a specific evaluation curve in dB.

Impact noise level index Lnw: value used to evaluate the insulating capacity of a floor with respect to impact sound in a single number. It is determined by comparing the frequency response of the reduced floor impact sound level with a special evaluation curve in dB.

RAtran: a value used to evaluate the airborne sound insulation of a window. Represents the isolation of external noise generated by the flow of urban traffic in dBA.

Sound power: the amount of energy emitted by the noise source per unit time, W.

Sound power level: ten times the base 10 logarithm of the ratio of sound power to threshold sound power (wo = 10 -12 W).

Sound absorption coefficient a: the ratio of the amount of sound energy not reflected from the surface to the amount of incident energy.

Equivalent absorption area (surface or object): surface area with a sound absorption coefficient a = 1 (totally absorbing sound) that absorbs the same amount of sound energy as a given surface or object.

Average sound absorption coefficient asr: the ratio of the total equivalent absorption area in the Asum room (including the absorption of all surfaces, equipment and people) to the total area of ​​all surfaces in the Scym room. -> asr=Asum/Ssum

Noise maps of the road network, railways, air transport, industrial zones and individual industrial and energy facilities: maps of territories with noise sources with plotted lines different levels sound on the ground with an interval of 5 dBA.

4.4. Octave sound pressure levels L in dB at the design points of rooms in which there are several noise sources should be determined:

a) in the zone of direct and reflected sound according to the formula

Octave sound power level in dB generated by the i-th noise source;

The same as in formulas (1) and (2), but for the i-th noise source;

m is the number of noise sources closest to the design point (i.e. noise sources for which , where is the distance in m from the design point to the acoustic center of the noise source closest to it);

n is the total number of noise sources in the room;

B and - the same as in formulas (1) and (3);

b) in the zone of reflected sound according to the formula

(6)

The first term in formula (6) should be determined by summing up the sound power levels of noise sources according to Table. 5, and if all noise sources have the same sound power, then

Table 5

Difference between two added levels in dB

Addition to the higher level needed to get the total dB level

Note. When using the table 5, the levels in dB (sound power or sound pressure) should be added sequentially, starting from the maximum. First, you should determine the difference between the two added levels, then the additive corresponding to this difference. After that, the additive should be added to the larger of the stacked levels. The resulting level is added to the next one, and so on.

4.5. Octave sound pressure levels L in dB at the calculated points, if the noise source and the calculated points are located on the territory of residential development or on the site of the enterprise, should be determined by the formula

where is the octave sound power level in dB of the noise source;

Ф - the same as in formulas (1) and (2);

r is the distance in m from the noise source to the calculated point;

Spatial angle of sound emission accepted for noise sources located:

in space -

on the surface of the territory or enclosing structures of buildings and structures -

in a dihedral angle formed by the enclosing structures of buildings and structures -

Attenuation of sound in the atmosphere in dB / km, taken according to Table. 6.

determined by formula (7), if the calculated points are located at distances

r in m, large doubled maximum size noise source.

2. At a distance m, the attenuation of sound in the atmosphere in the calculations is not

taken into account.

Table 6

Geometric mean frequencies of octave bands in Hz

4.6. The octave sound power level of noise in dB that has passed through the barrier (enclosing structure of the room) (Fig. 4, a, b) or a channel connecting two rooms or a room with the atmosphere, if the noise is generated by a source in the room (Fig. 4, c), should be determined by the formula

where L is the octave sound pressure level in dB at the barrier, determined according to the instructions note. 3 and 4 to this paragraph;

The area of ​​the barrier in sq.m;

The reduction in the sound power level of noise in dB when sound passes through an obstacle, determined according to the instructions of note. 1 and 2 to this paragraph;

Adjustment in dB to account for the nature of the sound field at incidence sound waves on the barrier, determined according to the instructions note. 3 and 4 to this paragraph.

Notes: 1. If the barrier is a building envelope

premises, then , where R is the airborne sound insulation of the enclosing

design in the octave frequency band, determined according to the requirements

section 6 of these rules.

2. If the barrier is a channel with an inlet area,

it is equal to the total reduction in sound power in the octave band in

channel determined in accordance with the requirement of section 8 of these standards.

3. When sound waves are incident on an obstacle from the atmosphere = 0, and L

should be determined by formulas (7) and (11).

Fig.4. Layout of noise sources and design points

ISH - source of noise; RT - calculated point; A - intermediate point; I - room

with sources of noise; II - atmosphere; III - room protected from noise

4.7. The octave sound power level of the noise in dB that has passed through the channel, if the noise is emitted by the source directly into the channel connected to another room or to the atmosphere (Fig. 5), should be determined by the formula

where is the sound power level in dB radiated by the noise source into the channel, determined in accordance with the instructions of sections (8) and (9) of these standards;

Total reduction in octave sound power level in dB along the sound path.

Rice. Fig. 5. The layout of the source (IS) emitting noise into the channel, and the calculated point (RT),

located in a noise-protected room in another building

Distance from the outlet of the channel to the outer fence of the room protected from noise;

Distances from the center of the radiating surface to the outer enclosure of the room protected from noise

The total reduction in the octave level of the sound power of the noise source along the sound propagation path in dB should be determined:

when emitting sound through the duct outlet - in accordance with the instructions in section 8 of these standards as the sum of sound power levels in the elements of the duct or duct system, for example, a network of ventilation ducts;

when sound is emitted through the walls of the channel - according to the formula

Reducing the octave sound power level in dB along the sound propagation path between the noise source and the initial section of the channel section through which noise is emitted, determined in accordance with the requirements of Section 8 of these standards;

Area in sq.m of the cross section of the channel;

Area in square meters of the outer surface of the channel walls through which noise is emitted;

Airborne noise isolation in dB by the channel walls;

The reduction in sound power level in dB along the length of the channel section under consideration, determined in accordance with the requirements of Section 8 of these standards.

4.8. Octave sound power levels in dB of noise that has passed through the barrier into the noise-protected room, if the noise sources are located in a room located in another building (Fig. 5), should be determined sequentially.

First, you should determine the octave sound power levels of noise in dB that has passed through various barriers from a room with a source (or several sources) of noise into the atmosphere, using formulas (8) and (9). Then it is necessary to determine the octave levels of noise sound pressure in dB at the intermediate design point A at the outer enclosing structure of the room protected from noise according to formula (7), replacing L in it with , and with . After that, you should determine the total octave sound pressure levels in dB at point A using formula (11), and then determine the octave sound power levels of the noise that passed into the room protected from noise, PR in dB using formula (8), replacing L with and accepting =0.

4.9. The octave levels of sound pressure at the design point in dB that passed through the barrier should be determined by formulas (3), (6) or (7), replacing L with and with .

4.10. Octave sound pressure levels from several noise sources in dB should be determined as the sum of the sound pressure levels in dB at the selected design point from each noise source (or each barrier through which noise penetrates into the room or into the atmosphere) according to the formula

To simplify the calculations, the summation of sound pressure levels should be carried out according to Table. 5 is similar to summing the sound power levels of noise sources.

4.11. The octave sound pressure level in dB at the design point for discontinuous noise from a single source should be determined by formulas (1) - (3) or (7) for each time interval in minutes during which the value of the octave sound pressure level in dB remains constant, replacing L in the above formulas with .

Then you should determine the equivalent octave sound pressure level in dB for the total noise exposure time T in minutes using the formula

(12)

where is the time in minutes during which the value of the sound pressure level in dB remains constant;

Constant value of the octave sound pressure level in dB of intermittent noise over time in minutes;

T is the total noise exposure time in minutes.

Note. For the total time of exposure to noise T in min should be taken:

in industrial premises - the duration of the work shift;

in areas for which noise levels are established - the duration of the day - (from 7 to 23 h) or night (from 23 to 7 h).

4.12. The octave sound pressure level in dB at the design point for impulse noise from a single source should be determined by formulas (1) - (3) or (7) for each individual impulse with a duration in minutes with an octave sound pressure value in dB, replacing L in the indicated formulas on the .

Then you should determine the equivalent octave sound pressure level in dB for the selected time interval T in min according to formula (12), replacing it with and with .

4.13. Equivalent octave sound pressure levels in dB at the design point for intermittent and impulsive noise from several noise sources should be determined in accordance with clause 4.10 of these standards, replacing a with.

5. Determining the required noise reduction

5.1. The required reduction in octave sound pressure levels in dB should be determined separately for each noise source, if the design point receives noise from several noise sources.

Note. This rule does not apply to the determination of the required noise reduction from noise sources in industrial premises (in the shops of the textile industry, woodworking, metalworking, etc.).

5.2. The required reduction in octave sound pressure levels in dB at the calculated point in the room or on the territory for one or several noise sources that differ from each other in octave sound pressure levels by less than 10 dB should be determined:

a) for one noise source according to the formula

b) for several noise sources according to the formula

where L and - octave sound pressure levels in dB, created respectively by one or separately considered noise source at the design point, determined in accordance with paragraphs. 4.2 - 4.8 of these standards;

Permissible octave sound pressure level in dB at the design point, determined in accordance with paragraphs. 3.4 and 3.5 of these standards;

n is the total number of noise sources taken into account, determined in accordance with paragraphs. 5.4 and 5.5 of these rules.

5.3. The required reduction in octave sound pressure levels in dB at the design point in the room or on the territory from several noise sources that differ from each other in octave sound pressure levels by more than 10 dB should be determined:

a) for each noise source with higher sound pressure levels according to the formula

where is the total number of noise sources with higher sound pressure levels;

b) for each noise source with lower sound pressure levels according to the formula

= , (16)

where n is the total number of noise sources taken into account, determined in accordance with paragraphs. 5.4 and 5.5 of these rules.

5.4. In the total number of noise sources n, when determining the required reduction in octave sound pressure levels in dB at design points located on the territory of residential development or on the sites of industrial enterprises, all noise sources located in these territories (aggregates, installations, etc.) should be included. ), as well as the number of elements of the enclosing structures of buildings and structures (walls or windows, coatings, etc.) oriented towards the design points through which noise from the room enters the design point, as well as outlets (openings) of channels and shafts emitting noise to the atmosphere.

When determining in dB for design points in a room protected from external noise sources, the total number n of noise sources taken into account should include the number of mechanically driven ventilation systems serving this room, as well as the number of building envelope elements through which noise penetrates into room.

Note. Noise sources located in the room protected from noise should not be taken into account, but the value should be increased by 5 dB.

5.5. In the total number of noise sources n, one should not take into account those noise sources that create sound pressure levels in dB below the permissible values ​​at the design point by the value , in each octave band, i.e. for which the relation

In this case, the value in dB should be determined by the formula

where is the number of noise sources whose sound pressure levels are at least 10 dB less than .

5.6. When determining by formula (7) octave sound pressure levels in dB from various noise sources to calculate the required reduction in sound pressure levels in dB at the calculated point using formulas (15) and (16), it is allowed to take the distances to noise sources the same and equal to the arithmetic mean in cases where 1.5 r min for different noise sources.

For noise sources with the same radiated power, in this case it is sufficient to calculate the required reduction in the sound pressure level for one of the sources, taking

The required sound pressure level reduction in dB will then be the same for all noise sources.

5.7. The required total reduction in octave sound pressure levels in dB in rooms with noise sources with simultaneous operation of all noise sources should be determined by the formula

where is the octave sound pressure level at the design point from all noise sources in dB, determined in accordance with clause 4.4 of these standards, replacing L by ;

Permissible octave sound pressure level in dB at the design point, determined in accordance with paragraphs. 3.4. and 3.5 of these rules.

6. Sound insulation of building envelopes

Soundproofing standards for building envelopes

6.1. Standardized parameters of sound insulation of enclosing structures of residential and public buildings, as well as auxiliary buildings and premises of industrial enterprises are the index of airborne sound insulation by the enclosing structure in dB and the index of the reduced impact noise level under the ceiling in dB.

6.2. Airborne sound insulation index in dB by a building envelope with a known (calculated or measured) frequency response of airborne sound insulation should be determined by the formula

where is the correction determined by comparing the frequency response of airborne noise insulation by the enclosing structure with the standard frequency response of airborne noise insulation (Fig. 6) according to the method described in Appendix. one.

Rice. 6. Regulatory frequency response isolation

airborne noise enclosing structure

6.3. The index of the normalized impact noise level in dB under a floor with a known (calculated or measured) frequency response of the normalized impact noise level should be determined by the formula

where is the correction determined by comparing the frequency response of the reduced impact noise level under the ceiling with the standard frequency response of the reduced impact noise level (Fig. 7) according to the method described in Appendix. one.

Rice. 7. Normative frequency response of the reduced level

impact noise under the ceiling

6.4. Normative indices of airborne noise insulation by enclosing structures in dB and the reduced level of impact noise under the floor in dB of residential and public buildings, as well as auxiliary buildings and premises of industrial enterprises, should be taken according to Table. 7.

Table 7

Name and location of the building envelope

Airborne sound insulation index

Impact sound level index in dB

residential buildings

Ceilings between apartments

Ceilings between apartments and unused attic spaces

Ceilings between the premises of the apartment and basements, halls and used attic spaces

Ceilings between the premises of the apartments and the shops located below

Ceilings between the premises of the apartment and the restaurants, gyms, cafes and other similar premises located below

Ceilings between rooms in a two-story apartment

Overlappings separating the premises of cultural and community services of hostels from each other and from the premises common use(halls, lobbies, corridors)

Walls and partitions between apartments, between apartment rooms and stairwells, halls, corridors, vestibules

Walls between the premises of the apartment and shops

Walls between the premises of the apartment and restaurants, gyms, cafes and other similar premises

Partitions without doors between rooms, between a kitchen and a room in an apartment

Partitions between rooms and a sanitary unit of one apartment

Entrance doors of apartments facing stairwells, halls, lobbies and corridors

Stairwells and marches.

* The requirement should be imposed on the transmission of impact noise to a room protected from noise during impact on the floor of a room that is not protected from noise.

Walls and partitions separating the premises of cultural and community services of hostels from each other and from common areas (halls, lobbies, stairwells)

Hotels Overlaps between rooms:

Ceilings separating rooms from common areas (lobbies, halls, buffets):

" " second "

* The requirement should be imposed on the transmission of impact noise to a room protected from noise during impact on the floor of a room that is not protected from noise.

Ceilings separating rooms from restaurants, cafes, canteens, kitchens:

" " second "

* The requirement should be imposed on the transmission of impact noise to a room protected from noise during impact on the floor of a room that is not protected from noise.

Walls and partitions between rooms:

Walls and partitions that separate rooms from common areas (stairwells, lobbies, halls, buffets):

" " second "

Walls and partitions that separate rooms from restaurants, cafes, canteens, kitchens:

" " second "

Buildings of administrations, party and public organizations Ceilings between work rooms, offices, secretariats and separating work rooms, offices, secretariats from common areas (lobbies, halls)

Ceilings separating working rooms, offices from working rooms that are not protected from noise (mashroom, teletype rooms, etc.)

Walls and partitions between work rooms

Walls and partitions that separate work rooms, secretariats from common areas (stairwells, lobbies, halls) and workers that are not protected from noise

Walls and partitions separating offices from workers, rooms not protected from noise and common areas

Hospitals and sanatoriums Ceilings between wards, doctors' offices

Ceilings between operating rooms and separating operating rooms from wards and offices

Ceilings separating wards, doctors' offices from common areas (lobbies, halls)

Ceilings separating wards, offices from dining rooms, kitchens

* The requirement should be imposed on the transmission of impact noise to a room protected from noise during impact on the floor of a room that is not protected from noise.

Walls and partitions between wards, doctors' offices

Walls and partitions between operating rooms and separating operating rooms from other rooms. Walls and partitions separating wards and offices from dining rooms, kitchens

Walls and partitions separating wards, offices from common areas (stairwells, lobbies, halls)

Schools and other educational institutions Ceilings between classrooms, classrooms and auditoriums and separating classrooms, classrooms and auditoriums from common areas (corridors, lobbies, halls)

Overlaps between music classes in secondary schools

Overlaps between music classes in higher education

Walls and partitions between classrooms, classrooms and auditoriums and separating classrooms, classrooms and auditoriums from common areas (stairwells, lobbies, halls, recreations)

Walls and partitions between music classes of secondary educational institutions and separating them from common areas (stairwells, lobbies, halls, recreations)

Walls and partitions between music classrooms of higher educational institutions

Kindergartens Ceilings between group rooms, bedrooms and between other children's rooms

Ceilings separating group rooms, bedrooms from kitchens

Walls and partitions between group rooms, bedrooms and between other children's rooms

Walls and partitions separating group rooms, bedrooms from kitchens.

Auxiliary buildings and premises of industrial enterprises Ceilings between the premises for recreation, training sessions, health centers, work rooms of departments and design bureaus, offices, premises of public organizations and separating these premises from common areas (lobbies, dressing rooms)

Ceilings between the premises of laboratories, red corners, meeting rooms, canteens and separating these premises from the premises indicated in position 44 of this table

Walls and partitions between the working rooms of departments and design bureaus, premises of public organizations

Walls and partitions between the premises for recreation, training sessions, health centers, separating these premises from the working rooms of departments and design bureaus, offices, premises of public organizations and separating all these premises from common areas (lobbies, dressing rooms, stairwells)

Walls and partitions between the rooms of laboratories, red corners, meeting rooms, canteens and separating these rooms from the rooms indicated in pos. 44 of this table

Note. The values ​​of airborne noise insulation indexes by enclosing structures and the reduced level of impact noise under ceilings for living rooms in dormitories should be taken the same as for the enclosing structures of apartments in residential buildings.

7.1 Settlement points in production and auxiliary premises of industrial enterprises are selected at workplaces and (or) in areas of permanent residence of people at a height of 1.5 m from the floor. In a room with one source of noise or with several sources of the same type, one calculated point is taken at the workplace in the zone of direct sound of the source, the other - in the zone of reflected sound at the place of permanent residence of people who are not directly related to the work of this source.

In a room with several noise sources, the sound power levels of which differ by 10 dB or more, the calculated points are selected at workplaces near sources with maximum and minimum levels. In a room with group placement of the same type of equipment, the design points are selected at the workplace in the center of groups with maximum and minimum levels.

7.2 The initial data for acoustic calculation are:

Plan and section of the premises with the location of technological and engineering equipment and design points;

Information about the characteristics of the enclosing structures of the room (material, thickness, density, etc.);

Noise characteristics and geometric dimensions of noise sources.

7.3 Noise characteristics of technological and engineering equipment in the form of octave sound power levels L w, corrected sound power levels L wA, as well as equivalent L wA eq and maximum L wA Max corrected sound power levels for intermittent noise sources must be specified by the manufacturer in the technical documentation.

It is allowed to represent noise characteristics in the form of octave sound pressure levels L or sound levels in the workplace L A(at a fixed distance) with a single operating equipment.

7.4 L, dB, at the calculated points of proportionate rooms (with the ratio of the largest geometric dimension to the smallest not more than 5) during the operation of one noise source should be determined by the formula

where L w- octave sound power level, dB;

χ - coefficient taking into account the influence of the near field in cases where the distance r less than twice the maximum size of the source ( r < 2l Max) (accepted according to table 2);

F- directivity factor of the noise source (for sources with uniform radiation F = 1);

Ω - spatial angle of radiation source, rad. (accepted according to table 3);

r- distance from the acoustic center of the noise source to the calculated point, m (if the exact position of the acoustic center is unknown, it is assumed to coincide with the geometric center);

k- coefficient taking into account the violation of the diffuseness of the sound field in the room (accepted according to table 4 depending on the average sound absorption coefficient α Wed);

AT- acoustic constant of the room, m 2, determined by the formula

BUT- equivalent sound absorption area, m 2, determined by the formula

(3)

α i- sound absorption coefficient i-th surface;

S i - square i-th surface, m 2;

BUT j- equivalent sound absorption area j-th piece absorber, m 2;

n j- amount j th piece absorbers, pcs.;

α cp- average sound absorption coefficient, determined by the formula

S ogre - the total area of ​​the enclosing surfaces of the room, m 2.

table 2

r /l Max		10 lg χ , dB

Table 3

Radiation conditions		10 lgΩ, dB
Into space - a source on a column in a room, on a mast, a pipe
Into the half-space - the source on the floor, on the ground, on the wall
In 1/4 space - source in dihedral corner (on the floor close to one wall)
In 1/8 space - source in trihedral corner (on the floor close to two walls)

Table 4

α cp		10 lg k, dB

7.5 Boundary Radius r gr , m, in a room with one noise source - the distance from the acoustic center of the source, at which the energy density of the direct sound is equal to the energy density of the reflected sound, is determined by the formula

If the source is located on the floor of the room, the boundary radius is determined by the formula

(6)

Calculated points up to 0.5 r gr can be considered as being in the area of ​​direct sound. In this case, the octave sound pressure levels should be determined by the formula

Design points more than 2 r gr can be considered as being in the area of ​​effect of the reflected sound. In this case, the octave sound pressure levels should be determined by the formula

7.6 Octave sound pressure levels L, dB, at design points of a commensurate room with several noise sources should be determined by the formula

(9)

where L wi - octave sound power level i-th source, dB;

χ i , F i , r i - the same as in formulas (1) and (6), but for i-th source;

m- the number of noise sources closest to the design point (located at a distance r i ≤ 5 r min, where r min- distance from the calculated point to the acoustic center of the nearest noise source);

n - the total number of noise sources in the room;

k and AT- the same as in formulas (1) and (8).

If everyone n sources have the same sound power L wi, then

(10)

7.7 If the noise source and the calculated point are located on the territory, the distance between them is greater than twice the maximum size of the noise source and there are no obstacles between them that screen the noise or reflect the noise in the direction of the calculated point, then the octave sound pressure levels L, dB, at the design points should be determined:

with a point source of noise (a separate installation on the territory, a transformer, etc.) - according to the formula

with an extended source of limited size (a wall of an industrial building, a chain of shafts of ventilation systems on the roof of an industrial building, a transformer substation with a large number of open transformers) - according to the formula

where L w , r,F, Ω - the same as in formulas (1) and (7);

β a- sound attenuation in the atmosphere, dB / km, taken according to table 5.

At a distance r ≤ 50 m, sound attenuation in the atmosphere is ignored.

7.8 Octave sound pressure levelsL, dB, at design points in an isolated room, penetrating through the building envelope from an adjacent room with a source (sources) of noise or from the territory, should be determined by the formula

where L sh- octave sound pressure level in a room with a noise source at a distance of 2 m from the fence separating the room, dB, is determined by formulas (1), (8) or (9); with noise penetrating into the isolated room from the territory, the octave sound pressure level L sh outside at a distance of 2 m from the building envelope is determined by formulas (11) or (12);

R - isolation of airborne noise by the enclosing structure through which the noise penetrates, dB;

S- area of ​​the enclosing structure, m 2;

AT and - acoustic constant of the isolated room, m 2 ;

k - the same as in formula (1).

If the building envelope consists of several parts with different sound insulation (for example, a wall with a window and a door), R determined by the formula

(14)

where S i- square i-th part, m 2;

R i - airborne sound insulation i-th part, dB.

If the enclosing structure consists of two parts with different sound insulation (R 1 > R 2), R determined by the formula

(15)

At R 1 >> R 2 with a certain ratio of areas is allowed instead of soundproofing the building envelope R when calculating according to formula (13), introduce sound insulation of the weak part of the composite fence R 2 and its area S 2 .

Equivalent and maximum sound levels L BUT, dBA, created by external transport and penetrating into the premises through the outer wall with a window (windows), should be determined by the formula

where L A 2 m- equivalent (maximum) sound level outside at a distance of 2 m from the fence, dBA;

R A trans.o- isolation of external traffic noise by a window, dBA;

S about- area of ​​the window (windows), m 2;

k - the same as in formula (1).

Table 5

For premises of residential and administrative buildings, hotels, hostels, etc. up to 25 m2 L A, dBA, is determined by the formula

(17)

7.9 Octave sound pressure levels in a noise-protected room in cases where noise sources are located in another building should be determined in several stages:

1) determine the octave sound power levels of noise, dB, passed through the outer fence (or several fences) to the territory, according to the formula

where L wi - octave sound power level i-th source, dB;

AT sh - acoustic constant of the room with the source (sources) of noise, m 2 ;

S- area of ​​​​the fence, m 2;

R- insulation of airborne noise by a fence, dB;

2) determine the octave sound pressure levels for the auxiliary design point at a distance of 2 m from the outer fence of the room protected from noise according to the formulas (10) or (11) from each of the noise sources (ISh 1 and Ish 2, Figure 1). When calculating, it should be taken into account that for the calculated points within 10 ° from the plane of the building wall (in Figure 1 - a complex noise source ISH 1), a correction for radiation directivity 10 lg is introduced F= -5 dB;

3) determine the total octave sound pressure levels L sum , dB, at the auxiliary design point (at a distance of 2 m from the outer fence of the room protected from noise) from all noise sources according to the formula

(19)

where L i - sound pressure level from i-th source, dB;

4) determine the octave levels of sound pressure L, dB, in a room protected from noise according to formula (13), replacing in it L sh on the L sum .

7.10 With intermittent noise, octave sound pressure levels L j , dB, at the calculated point should be determined by formulas (1), (7), (8), (9), (11), (12) or (13) for each time interval τ j, min, during which the level remains constant, replacing in the indicated formulas L on the L j .

RT - calculated point;

RT1 - auxiliary design point;

ISH 1 and ISH 2 - buildings - sources of noise

Picture 1 - Calculation scheme

Equivalent octave sound pressure levels L eq , dB, for the total exposure time T, min, should be determined by the formula

(20)

where τ j- level exposure time L j, min;

L j - octave level over time τ j, dB.

For the total time of exposure to noise T accept: in production and office premises - the duration of the work shift; in residential and other premises, as well as in territories where the norms are set separately for day and night, the duration of the day is 7.00 - 23.00 and the night is 23.00 - 7.00 h.

It is allowed in the latter case to take for the time of exposure T during the day - a four-hour period with the highest levels, at night - a one-hour period with the highest levels.

7.11 Equivalent sound levels of intermittent noise L Aeq, dBA, should be determined by formula (20), replacing L eq on the L Aeq and L j on the L Aj .

8.16. The total reduction in sound power levels in dB along the noise propagation path should be determined sequentially for each element of the duct network and then summed up using the formula

(65)

where is the reduction in octave levels of sound power in individual elements of air ducts in dB, determined according to paragraphs. 8.17 - 8.22 of these rules;

nc- number of elements of the duct network, in which the reduction of sound power levels is taken into account.

8.17. The decrease in octave levels of sound power in dB per 1 m of length in straight sections of metal air ducts of rectangular and round sections should be taken according to Table. twenty.

8.18. The decrease in octave sound power levels in dB in straight sections of brick and concrete channels is taken into account in the calculations.

Table 20

Duct cross-sectional shape	Hydraulic diameter in mm	Reduction of sound power levels also at geometric mean frequency of octave bands in Hz
Rectangular	75 to 200	0,6	0,6	0,45	0,3	0,3	0,3	0,3	0,3
» 210 » 400	0,6	0,6	0,45	0,3	0,2	0,2	0,2	0,2
» 410 » 800	0,6	0,6	0,3	0,15	0,15	0,15	0,15	0,15
» 810 » 1600	0,45	0,3	0,15	0,1	0,06	0,06	0,06	0,06
Round	75 to 200	0,10	0,1	0,15	0,15	0,3	0,3	0,3	0,3
» 210 » 400	0,06	0,1	0,1	0,15	0,2	0,2	0,2	0,2
» 410 » 800	0,03	0,06	0,06	0,1	0,15	0,15	0,15	0,15
» 810 » 1600	0,03	0,03	0,03	0,06	0,06	0,06	0,06	0,06

8.19. The decrease in octave levels of sound power in dB at the turns of the ducts should be determined from Table. 21. When the angle of rotation is less than or equal to 45 degrees, the reduction in octave sound power levels is not taken into account.

For smooth turns of air ducts and turns of air ducts at right angles and equipped with guide vanes, the reduction in octave sound power levels in dB should be taken from Table. 22.

Table 21

Turning width d in mm	Decrease in octave sound power levels in dB at the geometric mean frequency of the octave bands in Hz

Table 22

Turning width d in mm	Reduction of sound power levels in dB at the geometric mean frequency of the octave bands in Hz
125 - 250
260 - 500
510 - 1000
1100 - 2000

8.20. The decrease in octave sound power levels in dB with a change in the cross section of the duct should, depending on the frequency and dimensions of the cross section of the ducts, determine:

a) with dimensions of the cross-section of the duct in mm, less than those indicated in Table. 23, according to the formula

(66)

where t p- the ratio of the cross-sectional areas of the duct, equal to:

F 1 and F 2 - cross-sectional area of ​​the duct before and after changing the section in m 2;

b) with cross-sectional dimensions of the duct in mm, greater than those indicated in Table. 23, according to the formulas:

(at >1) (68)

(at<1) (69)

With a smooth transition of the air duct from one section to another, the reduction in octave levels of sound power is not taken into account.

8.21. Decrease in octave levels of sound power in dB in the branching of the duct should be determined by the formula

(70)

where t p- the ratio of the cross-sectional areas of the air ducts, equal to:

F- cross-sectional area of ​​the duct before branching in m 2 ;

F resp, i- cross-sectional area of ​​​​the duct of a separate branch in m 2;

The total cross-sectional area of ​​the air ducts of all branches in m 2.

Table 23

Note. If the air duct of a separate branch in the branch is rotated by 90 °, then the value in dB obtained by formula (70) should be supplemented with the reduction in octave sound power levels determined from Table. 21 or 22.

8.22. The decrease in octave levels in sound power in dB as a result of sound reflection from the open end of the duct or grille should be determined from Table. 24.

Table 24

Duct diameter or square root of the cross-sectional area of ​​the end of a rectangular duct or grille in mm	Decrease in octave sound power levels in dB at the geometric mean frequency of the octave band in Hz
2500
Note. The data in this table refer to the case when the duct ends flush with the wall or ceiling and is located, like the air distribution device (grille), at a distance of two or more duct diameters from other walls or ceiling. If an air duct or an air distribution device (grille) ending flush with the building envelope are located closer to other building envelopes, then the reduction in octave sound power levels should be determined from Table 24, assuming the value in dB for the duct diameter doubled.

Silencer design

8.23. In ventilation, air conditioning and air heating systems, tubular, plate and chamber silencers (Fig. 19) with sound-absorbing material should be used, as well as lining of air ducts and turns from the inside with sound-absorbing materials.

The choice of silencer design should be made depending on the size of the air duct, the allowable air flow velocity and the required reduction in octave sound pressure levels.

Rice. 19. Diagram of muffler designs

a - lamellar with extreme plates; b - lamellar without extreme plates; in - tubular rectangular section; g - tubular round section; d - chamber; 1 - muffler casing; 2 - sound absorbing plate; 3 - channels for air; 4 - sound-absorbing lining; 5 - internal partition

8.24. Tubular silencers should be used for duct sizes up to 500-500 mm. For large air ducts, plate or chamber silencers should be used.

Note. If there is an appropriate justification, the use of silencers of other types is permissible. Honeycomb mufflers are not allowed to be used in ventilation, air conditioning and air heating systems.

8.25. Plate silencers should be designed from sound-absorbing plates installed in parallel at some distance from each other in a common casing.

The thickness of sound-absorbing plates for silencers should be taken from Table. 25.

Table 25

8.26. Decrease in octave sound power levels in dB in air ducts and bends, lined with sound-absorbing material from the inside, and in mufflers should be determined from experimental data.

8.27. The reduction in octave sound pressure levels in dB in air intake devices (such as chambers) with sound-absorbing lining should be determined by the formula

(72)

where - - total sound absorption of a separate chamber in m 2 (sound absorption of the floor is not taken into account);

where Q- volumetric air flow through the muffler in m 3 / s;

Permissible air velocity in the muffler in m/s, taken depending on the available pressure losses and the level of noise generation in the muffler.

For residential and public buildings, auxiliary buildings and premises of enterprises, it is allowed to take the speed of air movement in silencers according to Table. 26, if the length of the duct section to the room is at least 5 - 8 m.

Table 26

8.29. When designing ventilation, air conditioning and air heating, it is necessary to provide for the installation of a central silencer and place it as close as possible to the fan at the beginning of the ventilation network.

To muffle the noise generated in the air ducts during the movement of the air flow, as well as the noise penetrating into the air ducts from the outside from other sources of noise, on the branches of the air duct, it is necessary to provide additional installation of silencers according to the calculation.

8.30. In rooms for ventilation equipment, the outside air of the silencer and the air duct after it, located within the room for ventilation equipment, should be soundproofed from the outside so that the octave values ​​​​of airborne sound insulation by the walls of the silencer and the air duct are not less than the required value in dB, determined by the formula

where L- octave sound pressure level in the room for ventilation equipment in dB, determined by formula (6) and in accordance with paragraphs. 8.5 - 8.7 of these standards;

Surface area of ​​the muffler and air duct within the room for ventilation equipment in m 2 ;

- octave levels of sound power radiated by the fan into the duct in dB, determined by formula (57);

- total reduction in octave levels of sound power, in the sections of the air duct (including mufflers) from the fan to the exit from the room for ventilation equipment in dB, determined in accordance with paragraphs. 8.16 and 8.26 of these rules.

To reduce the value of the required insulation from airborne noise of the walls of the muffler and air ducts, sound-absorbing lining of the internal surfaces of the enclosing structures of the room for ventilation equipment can be used.

Similar information.

Sound pressure is the changing excess pressure that occurs in an elastic medium when a sound wave passes through it. Sound pressure level - the measured sound pressure value, relative to the reference pressure Рspl\u003d 20 μPa and the corresponding threshold of hearing of a sound wave with a frequency of 1 kHz. An increased sound pressure level is the cause of noise pollution. In order to determine the sound pressure level and determine measures to reduce it, a special calculation is made:

• identify the source (sources) of noise and its noise characteristics;
• select design points, determine the permissible level of sound pressure in them;
• calculate the expected sound pressure levels at the calculated points;
• calculate the required noise reduction;
• develop acoustic and architectural and construction measures to ensure noise reduction.

The sound pressure level is determined at the calculated points, selected either at workplaces or in areas with a permanent stay of people at a height of 1.5 m from the floor. Moreover, in a room with one or more identical sources, there are two points, one - at the workplace in the zone of direct sound, the second - in the zone of reflected sound and in the place of permanent residence of people. If there are several sources in the room, the sound power levels of which differ by 10 dB or more, the points are chosen at the workplaces near the sources with maximum and minimum levels.

Initial data for calculation:

• plan and section of the premises with the location of all types of production equipment and indication of design points;
• characteristics of enclosing building structures (material, thickness, density, etc.);
• noise characteristics and dimensions of noise sources.

The noise characteristics of the equipment are given by the manufacturer in the documentation. It can be: octave lw, corrected LwA, equivalent LwAeq or maximum LwAmax corrected sound power levels. Characteristics in the form of octave sound pressure levels are allowed L or sound levels in the workplace Ld(at a certain distance).

L, dB, at the design points of the premises (with a ratio of the largest to the smallest size of not more than 5) during the operation of one noise source should be determined by the formula (1) L = Lw +10 lg ((χ Ф)/(Ω r²) + 4/kB), where lw- octave sound power level, dB;

χ - coefficient taking into account the influence of the near field in cases where the distance r less than twice the maximum size of the source ( r<2lмакс ) (table data);

F- directivity factor of the noise source (for sources with uniform radiation F= 1);

Ω - spatial angle of radiation source, radians (table data);

r- size from the acoustic center of the noise source to the calculated point, m;

k- coefficient of distortion of the sound field in the room (table data, depending on the average sound absorption coefficient αav);

B- room acoustic constant, m², determined by formula (2) B = A /(1-αcp ),

BUT- equivalent sound absorption area, m², determined by the formula:

Si- area of ​​i-th surface, m²;

Aj- equivalent sound absorption area of ​​the j-th artificial absorber, m²;

nj- number of j-th artificial absorbers, pieces;

αcp- average sound absorption coefficient, determined by the formula (4) αcp = A /Slimit,

Sgr- the total area of ​​the enclosing surfaces of the room, m².

Boundary Radius r gr, m, in a room with one noise source - the distance from the acoustic center of the source, at which the energy density of the direct sound is equal to the energy density of the reflected sound, is determined by the formula (5) r gr \u003d √ (B / 4 Ω)

If the source is located on the floor of the room, the boundary radius is determined by the formula (6) r gr \u003d √ V / 8π \u003d √ V / 25.12

Calculated points at a distance of up to 0,5 r gr are considered to be in the zone of direct sound. In this case, the octave sound pressure levels should be determined by the formula (7) L \u003d Lw + 10 log Ф + 10 log χ - 20 log r - 10 log Ω.

Settlement points at a distance of more 2 r gr are considered to be in the zone of reflected sound. In this case, the octave sound pressure levels should be determined by the formula (8) L \u003d Lw - 10 log B - 10 log k + 6.

Octave sound pressure levels L, dB, at the calculated points of the room with several noise sources should be determined by the formula:

where L wi- octave sound power level of the i-th source, dB;

χi, Фi, ri- the same as in formulas (1) and (6), but for the i-th source;

m- the number of noise sources closest to the design point (located at a distance ri ≤ 5 rmin, where rmin- distance from the calculated point to the acoustic center of the nearest noise source);

n- the total number of noise sources in the room;

k and AT- the same as in formulas (1) and (8).

If everyone n sources have the same sound power Lwi, then

If the noise source and the calculated point are located in the same room, the distance between them is greater than twice the maximum size of the noise source, and there are no obstacles between them that shield or reflect the noise in the direction of the calculated point, then the octave sound pressure levels L, dB, at design points should be determined: with a point source of noise (separate installation on the territory, transformer, etc.) - according to the formula (11)

L \u003d Lw - 20 log r + 10 log F - βa r / 1000 - 10 log Ω;

with an extended source of limited size (wall of an industrial building, a chain of shafts of ventilation systems on the roof of an industrial building, a transformer substation with a large number of openly located transformers) - according to the formula (12)

L \u003d Lw - 15 lg r + 10 lg F - βa r / 1000 - 10 lg Ω;

where Lw, r, Ф, Ω- the same as in formulas (1) and (7);

βa- sound attenuation in the atmosphere, dB/km (table data).

At a distance r ≤ 50 m attenuation of sound in the atmosphere is not taken into account.

Octave sound pressure levels L, dB, at calculated points in an isolated room, penetrating through the building envelope from an adjacent room with a source (sources) of noise or from the territory, should be determined by formula (13)

L = Lsh – R + 10 log S – 10 log B and – 10 log k,

where Lsh- octave sound pressure level in a room with a noise source at a distance of 2 m from the fence separating the room, dB, is determined by formulas (1), (8) or (9); with noise penetrating into the isolated room from the territory, the octave sound pressure level Lsh outside at a distance of 2 m from the building envelope is determined by formulas (11) or (12);

R- isolation of airborne noise by the enclosing structure, through which the noise penetrates, dB;

S- area of ​​the enclosing structure, m²;

In and- acoustic constant of the isolated room, m²;

k- the same as in formula (1).

If the building envelope consists of several parts with different sound insulation (for example, a wall with a window and a door), R determined by the formula:

where Si- area of ​​i-th part, m²;

Ri- isolation of airborne noise by the i-th part, dB.

If the building envelope consists of two parts with different sound insulation ( R1>R2), R determined by the formula:

At R1>>R2 and a certain ratio S1/S2 allowed instead of soundproofing the building envelope R when calculating according to formula (13), introduce sound insulation of the weak part of the composite fence R2 and its area S2.

Equivalent and maximum sound levels LA, dB, created by external transport and penetrating into the premises through the outer wall with a window (s), should be determined by the formula (16) L \u003d LA2m - RAtrans.o + 10 lg So - 10 lg B and - 10 lg k,

Where LA2m- equivalent (maximum) sound level outside at a distance of 2 m from the fence, dB;

RAtrans.o- isolation of external transport noise by a window, dB;

So- area of ​​the window(s), m²;

Bi is the acoustic constant of the room, m²(in the octave band 500 Hz);

k- the same as in formula (1).

For residential and administrative premises, hotels, hostels up to 25 m² LA, dB, determined by the formula (17) LA \u003d LA2m - RAtrans.o - 5.

Octave sound pressure levels in a noise-protected room in cases where noise sources are located in another building should be determined in several stages:

1) determine the octave sound power levels of the noise Lwpr , dB passed through the outer fence (or several fences) into the territory, according to the formula.