Transcript ENVIRONMENTAL NOISE1
ادخ مان هب
یبلطم دوعسم رتکد : هدننک هیهت http://healthf.kaums.ac.ir/ [email protected]
ENVIRONMENTAL NOISE SOURCES
1-Traffic noise 2-Constructional equipment noise 3-Industrial process noise 4-Aircraft noise 5-Railway noise 6-Miscellaneous noise
Most important factors affecting noise propagation
1-Type of source 2-Distance from source 3-Atmospheric absorption 4-Air temperature gradient 5-Wind 6-Barrier and building 7-Ground absorption 8-Plant covering
Apropagation = Adiv + Aatm + Agr + Abar + Amisc + Crefl Lp = LW+ Dc + Cb - Apropagation Lp Equivalent noise level at receiver point in dB LWSound power level of source in dB (ref = 1 pW) Dc Directivity correction in dB if the source does not emit sound equally in all directions Cb Correction in dB if the source is not always active. For example, the long term level is reduced by 3 dB if the source is active 12 hours a day Apropagation Propagation attenuation in dB
ATMOSPHERIC ATTENUATION
1-Distance 2-Frequancy 3-Temperature 4-Relative humidity 5-Ambient pressure
اب اوه طسوت توص بذج
سکع تبسن یبسن تبوطر میقتسم تبسن سناکرف سکع تبسن امد
دراد
TEMPERATURE GRADIENT
WIND
BARRIER
Effective distance
frequency
GROUND EFFECTS
ENVIRONMENTAL NOISE PARAMETERS
1
-
DL
(
L
d) : Daily average sound level
2
-
EL
(
L
e) : Evening ,, ,, ,,
3
-
NL
(
L
n) : Night ,, ,, ,,
4
-
24HL
: (24-hour ,, ,, ,,
5- DNL ( L dn) : Day-Night average sound level 6- CNEL ( L den) : community noise equivalent level 7- YCNEL : Year community noise equivalent level 8- LNP : Noise pollution level 9-SEL (
L
AE): Sound exposure level 10-TNI : Traffic noise index
11-Aircraft Noise Parameter : 11-1- LPN (Perceived noise level ) 11-2- LEPN (Effective perceived …) 11-3- NEF (Noise exposure forecast) 12-
L
r (Rating level) 13-Speech interference parameters: 13-1- PSIL (Preferred Speech Interference level) 13-2- PNC (Preferred noise criteria)
DL 15 HOUR (7-22)
L d= 10 log
[
1/15 S um antilog L 1h /10
]
EL 3 HOHR (19-22)
L
ev = 10 log
[
1/3 S um antilog
L
1h/10
]
NL 9 HOUR (22-7)
L
n =10 log
[
1/9 s um antilog
L
1h/10
]
24HL
L
24h = 10 log [1/24 (15 antilog
L
d/10) + (9 antilog
L
n/10)]
DNL ADDING 10 dB for night time
L
dn = 10 log
[
1/24[(15 antilog
L
d/10 ) +9
(
antilog {
L
n+10}/10
)]
]
CNEL
ADDING 10 dB for NIGHT AND 5 dB for EVENING L den = 10 log [ 1/24 [(sum antilog L h/10)+(3 antilog { L e+5}/10)+(9 antilog { L n +10}/10)] ]
YCNEL
FOR : WEEK ,MONTH , YEAR L deny=10 log [1/365 sum antilog L den/10]
LNP
L NP= L eq+ ( L 10 – L 90) L NP= L 50 + ( L 10 – L 90)/60] L 90) + [ ( L 10-
EXAMPLE
SEL
L eq = L AE – 10 log (T/t) T=86400 S L eq24h = 10 log 49.4
[ sum antilog L AE/10 ] L dn = 10 log [sum antilog L AEd ( L AEn +10)/10] + sum antilog
TNI
TNI = L 90 + 4( L 10 – L 90 ) – 30 L 10 – L 90 (NOISE CLIMATE)
Aircraft Noise Parameter :
LPN (Perceived noise level ) PN (Perceived noise):has been made to quantify perceived noisiness by means of a set of equal noisiness contours ;in the units NOYS were developed.
1 NOYS is defined as the perceived noisiness in the band from 910 to 1090 HZ (centered 1 KHZ ) with maximum sound pressure level of 40 dB.
PN=N m (1-K)+K sum N i noys Octavband---k=0.3 1/2octav---k=0.2 1/3octav---k=0.15
Aircraft Noise Parameter :
PNL=L PN =33.3 logPN+40 PNdB Short method : L PN =L D +7
Estimated method:
L
PN
=L
A
+13
Aircraft Noise Parameter :
ENPL (Effective perceived noise level)
L
EPN
=L
PN
+C+D
L EPN =L D +7+10 log (T / t) EPNdB t =15 s
Aircraft Noise Parameter :
NEF (NOISE EXPOSURE FORECAST) NEF ij =EPNL ij +10 log[N dij +17N nij ]-88 i : type of aircraft (707 ;747;etc) J : ,, ,, direction N d N n : number of fly (7 am – 22 pm) : ,, ,, ,, (22 pm -7 am ) NEF=10 log sum antilog {NEF ij / 10 }
55 - 60 dB = Light blue 60 - 70 dB = Dark blue 70 - 75 dB = Red 75 - 80 dB = Green 80 - 85 dB = Yellow > 85 dB = Pink
NEF Zones can be interpreted in terms of community reaction as follows : NEF<20 :NO COMPLIANTS EXPECTED 20
Rating Level (Annoyance and Penalties)
The Rating Level is defined in the ISO 1996-2 standard (see section on International Standards). It is basically a measure of the noise exposure corrected for factors known to increase annoyance. The basic parameter is the A-weighted equivalent continuous sound pressure level or LAeq.
The formula for the Rating Level is (in general terms):
Rating Level Lr -- How Much is Too Much?
International standards describe how to determine the Rating Level L r , but do not set legal limits. These are regulated individually by country or local authority. Differences in lifestyle, climate (outdoor activities, open or closed windows) and building design make international harmonisation of noise limits impossible.
Three Applications of Limits
As an example of national regulation, the Swiss use three kinds of limits: Planning values for new, industrial, transportation or housing areas Limits at dwellings for alterations or new installations Alarm values to identify areas for high priority noise abatement
PSIL (Preferred Speech Interference level) PSIL=(L 500 +L 1000 +L 2000 ) / 3
MEASUREMENT & ASSESSMENT (LIMITS) Noise of sources measurement.
Environmental Noise measurement.
MEASUREMENT of SOURSES
SWL or ?
SPL
MEASUREMENT of SOURCES
Measurement of SPL in specific distance (EPA) ,, ,, SWL of sources (ISO) Prediction of noise (calculation)
Measurement of SPL in specific distance Measurement of noise in specific distance (usually 1; 7 ; 15 meter) and different directions was done.
Then calculate Mean Different< 5dB ----- Mean 5dB
Measurement of SWL
Measurement in Reverbrant field.
SWL=SPL+10logV – 10logt – 14
ISO method
SWL=SPL+10log (S/s)
Environmental Noise Measurement.
ISO 1996 (Assessment of environmental noise) (part 1,2,3) ISO 3891 (Aircraft Noise Monitoring) ISO 9613 (Calculation) (part 1,2,3) IEC 60651 IEC 60804 IEC 61672
Environmental Noise Measurement.
Attended
Unattended
Permanent monitoring
In some cases it is vital for the operator to be present on-site to: Change or improve measurement setup Ensure representative measurement Identify and mark specific noise sources Identify and mark residual noise Prevent interference with equipment or measurement Advise workers using noisy equipment Mediate in conflicts over environmental issues
Attended measurements are often made under difficult conditions -- time is scarce, access to the site is difficult, mains power is unavailable or intermittent, unexpected events or interruptions occur, and the operator gets no second chance to make measurements. So the operator needs equipment that: Is easy to transport, set up and operate Has markers to identify events and noise sources Measures all parameters simultaneously Time-stamps all recorded data
For unattended measurements, preparation of equipment and setup must be made with great care and foresight, since the equipment must function entirely on its own. This requires: Wide dynamic range Data logging (e.g., every second or minute) Simultaneous measurement of all parameters Sound recording for noise source identification Weather data recording Time-stamp on all recorded data Huge storage capacity for data Automatic calibration check Remote access to data and setup (preferably) Back-up power supply Weatherproof microphone and equipment Protection against tampering and animals
For unattended measurements, the microphone needs protection against wind, rain and birds! It also has to be easily accessible for inspection and calibration
Permanent Noise Monitoring Systems
The Measurement Report
ISO 1996 states that the following information must be recorded:
Results Measurement technique Type of instrumentation used Measurement procedure used Calculations used Prevailing conditions Atmospheric conditions (wind direction and speed, rain, temperature, atmospheric pressure, humidity) Nature/state of ground between source and receiver Source variability Calibration data Measurement date, start and stop time Number of measurements made Description of the sound sources under investigation