NATIONAL AVIATION UNIVERSITY
Laboratory work
«Environmental noise monitoring»
SANITARY-HYGIENIC EVALUATION OF THE NOISE
Student
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Department _______________________
Group
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Date
Authors: Tokarev V.
Kyiv 2009
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Laboratory work
SANITARY-HYGIENIC EVALUATION OF THE NOISE
Purpose of the work:
- to acquaint with short information about methods of sanitary-hygienic protection
from noise;
- to familiarize with criteria of noise estimation and calculation methods of noise
characteristics.
Task
1. To study requirements of "Sanitary norms of allowable noise in inhabited, public
buildings and in territory of dwelling".
2. To study system of broadband noise estimation using of noise rating curves.
3. To analyze of excess over normative requirements of broadband noise in octave
frequencies bands.
4. To determine overall sound pressure level and sound level of broadband noise.
1. Short theoretical information
1.1. The basic terms
Acoustics is the science of the production, control, transmissions, receptions and
effects of sound and of phenomenon of hearing.
Sound is a longitudinal oscillation in pressure, particle displacement, particle velocity,
etc., in an elastic medium, or the superposition of such propagated alterations.
Noise is concerned with sounds, which annoy us and may have a long-term
physiological effect on an individual. Noise, as a rule, includes frequency oscillations and
emanating from aircraft, highways, industrial, commercial and residential sources.
Ambient noise is the total of all noise in the environment, other than the noise from
the source of interest. This term is used interchangeably with background noise.
A-weighted sound level ( LA ) is a measure of sound pressure level designed to reflect
the acuity of the human ear, which does not respond equally to all frequencies. The ear is
less efficient at low and high frequencies than at medium or speech-range frequencies.
Therefore, to describe a sound containing a wide range of frequencies in a manner
representative of the ear's response, it is necessary to reduce the effects of the low and
high frequencies with respect to the medium frequencies. The resultant sound level is said
to be A-weighted, and the units are dBA. The A-weighted sound level is also called the
noise level.
Broadband noise is noise with components over a wide range of frequencies.
Decibel is a unit of sound pressure level, abbreviated dB.
dBA is unit of sound level. The weighted sound pressure level by the use of the A
metering characteristic and weighting specified in ANSI Specifications for Sound Level
Meter, S1.4-1983. dBA is used as a measure of human response to sound.
Equivalent A-weighted sound level (LAeq, dBA) is the constant sound level that, in a
given time period, would convey the same sound energy as the actual time-varying Aweighted sound level.
Frequency (f) is the number of times per second that the sine wave of sound repeats
itself. Now expressed in hertz (Hz). Audio frequency is the frequency of oscillation of an
audible sound wave, any frequency between 20 and 20,000 Hz.
Harmonic is a sinusoidal (pure-tone) component whose frequency is a whole-number
multiple of the fundamental frequency of the wave. If a component has a frequency twice
that of the fundamental it is called the second harmonic, etc.
Spectrum is the description of a sound wave's resolution into its components of
frequency and amplitude.
Octave is the interval between two sounds having a frequency ratio of two.
Wavelength (  ) is characteristic of a periodic wave (such as sound in air). The
distance between analogous points on any two successive waves. The wavelength of
sound in air is inversely proportional to the frequency of the sound. Thus, the lower the
frequency, the longer the wavelength.
Sound power ( N ) is the total sound energy radiated by a source per unit time. The
unit of measurement is the watt.
Sound pressure (P) is the instantaneous difference between the actual pressure
produced by a sound wave and the average or barometric pressure at a given point in
space.
Sound pressure level (SPL) is 20 times the logarithm, to the base 10, of the ratio of
the pressure of the sound measured to the reference pressure, which is 20 micronewtons
per square meter. In equation form, sound pressure level in units of decibels is expressed
as SPL (dB) = 20 log p/pr.
Sound power level ( L p ) is 10 times the logarithm, to the base 10, of the ratio of the
sound power to reference sound power, which is 10 12 Wt.
Noise reduction (NR) is the numerical difference, in decibels, of the average sound
pressure levels.
1.2. Effect of noise
Sound, and hence noise, results from periodic disturbances of the air and at room
temperature is propagated in air at a speed of approximately 340 m/s. As the disturbance
spreads geometrically its effect will decrease with its distance from the sound source but
the diminution in sound intensity will also be affected by the damping of the sound waves
by the transmitting medium. This effect may arise in the atmosphere and is influenced by
the degree of humidity and sound frequency. It is of particular importance in a closed
space, where the geometrical spreading is almost eliminated. Typical sources of noise
include vibrating structures (such as a panel), air moving devices (fans, blowers, engines,
compressors), transportation noise.
Noise is a physical and social problem with several undesirable effects:
1. It can cause hearing loss if of sufficient level (a physical effect).
2. Causes annoyance (a psychological effect) which can result in sleep disturbance,
stress, tension, ability to work.
3. Interferes with activities, such as speech communication, which in turn can cause
annoyance and all of its associated effects.
4. Causes structural response (mechanical effect) which can cause structural failures,
injury, product liability.
A constitutionally guaranteed right for environmental protection was reflected in
federal law on protection atmospheric air: “About the protection of atmospheric air” (№
2556-ІІІ from 21.06.2001). In article 21 “Prevention and abatement noise” it is
concerned domestic and environmental noise measure of decreasing the main sources of
noise.
Steady noise restricted in according with setting norms (“Sanitary norms of allowable
noise in inhabited, public buildings and in territory of dwelling”) by means of limitation
sound pressure levels in octave frequency bands: 63, 125, 250, 500, 1000, 2000, 4000,
8000 Hz. For additional evaluation of noise A weighted sound level LA is used.
Equivalent sound level recommended for application in case sounds vary irregularly in
level.
1.3. The basic settlement formulas
Basic formulas for calculation are the following:
- summary sound pressure level
i 8
L  10 lg 10 0,1Li ( f } ,
i 1
where Li ( f ) is sound pressure level for i octave frequency band;
- sound level
i 8
L A  10 lg 10 0,1[ Li ( f )  Li ( f )] ,
i 1
where values of the spectral noise correction factors are resulted in the Table 1.
Table 1
The spectral noise correction
f, Гц
63
125
250
500
1000
2000
4000
8000
-
Li(f)
26,2
16,1
8,6
3,2
0
-1,2
-1,0
1,1
equivalent sound level
T
L Aeq  10 lg[
1
1
10 0,1LA (t ) dt ]  10 lg[

T0
T
jN
10
0.1LA ( t J )
t j ] ,
1
where L A (t j ) is sound level at the moment of time t j , t j is time separation of an
interval from 0 up to T at the moment of time t j .
Нормативні значення рівнів звукового тиску наведені в Талиці 2.
Table 2
Normative sound pressure levels
Type of rooms
Rooms of hospitals and sanatorium,
operational hospitals
Inhabited rooms of apartments,
rooms rest houses and boarding
houses, sleeping rooms in children's
preschool establishments
Cabinets of doctors of hospitals,
santeria, clinics, auditory of concert
halls, rooms of hotels, inhabited
rooms in hostels
Territories of hospitals, santeria,
adjoining to a building
Territories, directly adjoining to
to apartment houses (in 2 m from
protecting construction), platforms
of rest and groups of apartment
houses, platforms of nurseries up to
school establishments schools
Class rooms, educational cabinets, an
schools and other educational
institutions, halls, reading rooms,
auditory theatres, clubs, cinemas,
halls judicial
Working management’s rooms,
design bureau, design scientific
research centuries
Halls of cafe, restaurants, dining
rooms, foyer of theatres
Trading halls of shops, sports halls,
passenger halls of the airports,
stations, places of acceptance a
consumer services establishment
LA ,
Sound pressure levels in octave frequency
bands, Hz
dBA
63 125 250 500 1000 2000 4000 8000
51
39
31
24
20
17
14
13
25
55
44
35
29
25
22
20
18
30
59
48
40
34
30
27
25
23
35
59
48
40
34
30
27
25
23
35
67
57
49
44
40
37
35
33
45
63
52
45
39
35
32
30
28
40
71
61
54
49
45
42
40
38
50
75
66
59
54
50
47
45
43
55
79
70
63
58
55
52
50
49
60
2. The procedure of carrying out the laboratory work
Measured values of sound pressure levels in a working management’s rooms in octave
frequencies bands are resulted in Table 3. Experimental data of changeable noise (noise
from the passing automobile) are given in Table 5.
Execution sequence of carrying out of laboratory work:
- to determine summary sound pressure level;
- to determine sound level;
- to determine equivalent sound level;
- to compare the measured values of sound pressure levels with normalized values
(Table 4);
- to determine excess of sound pressure levels over normative requirements.
Table 3
Experimental sound pressure levels
Variant
L
LA
Sound pressure levels in octave frequency
bands, Hz
63
1
23
3
4
5
6
7
8
9
10
11
12
125 250 500 1000 2000 4000 8000
77
70
62
56
53
50
46
44
76
69
61
55
52
49
45
43
75
68
60
54
51
48
44
42
74
67
59
53
50
47
43
41
73
66
58
52
49
46
42
40
72
65
57
51
48
45
41
39
71
64
56
50
47
45
42
38
69
63
57
51
48
44
42
39
68
64
58
52
49
46
43
38
67
63
57
50
48
43
42
39
66
62
56
49
47
43
41
38
65
64
56
48
46
42
40
37
Table 4
Noise rating curves (NRC)
Mark of
noise
Variant
rating
curves
Noise rating curves in octave frequency
bands, Hz
63 125 250
1
500
LA ,
dBA
1000 2000 4000 8000
NRC-50
75
66
59
54
50
47
45
43
55
NRC -50
75
66
59
54
50
47
45
43
55
NRC -50
75
66
59
54
50
47
45
43
55
NRC -50
75
66
59
54
50
47
45
43
55
NRC -45
71
61
54
49
45
42
40
38
50
NRC -45
71
61
54
49
45
42
40
38
50
NRC -45
71
61
54
49
45
42
40
38
50
NRC -40
67
57
49
44
40
37
35
33
45
NRC -40
67
57
49
44
40
37
35
33
45
NRC -45
71
61
54
49
45
42
40
38
50
NRC -45
71
61
54
49
45
42
40
38
50
NRC -45
71
61
54
49
45
42
40
38
50
2
3
4
5
6
7
8
9
10
11
12
Table 5
Experimental data of changeable noise L A (t j ) , t j  1 s, T = 10 s
tj, s
Variant
1
2
3
4
5
6
7
8
9
10
11
12
1
31
33
42
44
47
45
55
52
54
56
57
58
2
40
42
45
47
51
49
58
56
58
67
68
69
3
45
47
53
55
53
51
61
58
61
72
74
77
4
53
49
60
61
64
60
66
63
62
78
80
83
5
57
51
63
62
69
67
69
64
63
81
83
86
6
60
57
65
60
68
66
68
63
61
83
85
88
7
54
51
62
58
64
61
65
60
57
80
81
83
8
51
48
59
54
59
55
61
56
51
75
77
78
9
43
41
51
49
53
50
57
51
47
71
68
74
10
37
38
44
43
46
48
51
47
41
64
61
69
L Aeq
3. Reporting requirements
Results of the calculations of summary sound pressure levels and sound levels which
have been carried out during laboratory work are resulted in the Table 3. The calculations
of equivalent sound level are to be filled in Table 5. To answer on control questions.
3.1. Conclusions on laboratory work
In this section brief conclusions on laboratory work are resulted. After construction of
graph (spectra) of the measured sound pressure levels (Table 3) and normative values
(Table 4), it is necessary to analyze excess measured sound pressure levels above
normalized values.
3.2. Key questions
1.
2.
3.
4.
5.
What is the difference between a sound and noise?
What is background noise?
What is ratio between calculated summary sound pressure level and sound level?
What type of a spectrum is submitted in Table 3?
To give definition of equivalent sound level.