SNA-Davis-Chapter 15 Noise (1)

7/23/2019 SNA-Davis-Chapter 15 Noise (1)

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Chapter 15Chapter 15

Principles of EnvironmentalPrinciples of Environmental

Engineering and ScienceEngineering and Science

3rd Edition3rd Edition

Mackenzie L. DavisMackenzie L. Davisndnd

S!san ". MastenS!san ". Masten

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Noise PollutionNoise Pollution

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The Decibel:The Decibel:

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=

oI

IdB log$%

=

oI

IdB log$%

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oP

PdB log"%

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=%%%%".%

log"% P

SPL

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log"% P

SPL

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Figure 15-3Figure 15-3( )elati*e scale o! sound pressure le*els( )elati*e scale o! sound pressure le*els

+Copyright McGraw-Hill Global Education Holdings, LLC. Permission reuired !or reproduction or display.


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Three SPLs 68 db, 79 dB and 75Three SPLs 68 db, 79 dB and 75

dBdB

What is SPL o co!bination"What is SPL o co!bination"



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Figure 15-4Figure 15-4( Graph !or sol*ing decibel addition( Graph !or sol*ing decibel addition

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'. d'. d

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$%&S'()N* SPL$%&S'()N* SPL

+ T-e )) sound Le.el $eterT-e )) sound Le.el $eter

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+ 1cta.e Band &nalsis1cta.e Band &nalsis

+ Narro2 BandNarro2 Band

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T3P%S 14 N1)S%T3P%S 14 N1)S%

+0ontinuous0ontinuous

'ninterru-ted, .aries less than'ninterru-ted, .aries less than 5 dB5 dB

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)nterru-ted or sec)nterru-ted or sec

+)!-ulsi.e )!-ulse)!-ulsi.e )!-ulse 0han/e SPL ; dB in less than


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Figure 15-11Figure 15-11( Cross section through the cochlea( Cross section through the cochlea

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Figure 15-14Figure 15-14( 1arious degrees on in2ury to hair cells( 1arious degrees on in2ury to hair cells

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Figure 15-13Figure 15-13( 3n audiogram illustrating e4cellent hearing( 3n audiogram illustrating e4cellent hearing

responseresponse$'



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Figure 15-15Figure 15-15( 3n audiogram illustrating hearing loss at high( 3n audiogram illustrating hearing loss at high

!reuency notch!reuency notch$+



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Figure 15-16Figure 15-16(5678H occupational noise e4posure limits !or(5678H occupational noise e4posure limits !or

continuous or intermittent noise e4posurecontinuous or intermittent noise e4posure $Copyright McGraw-Hill Global Education Holdings, LLC. Permission reuired !or reproduction or display.


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)N>%(S% S?'&(% L&W)N>%(S% S?'&(% L&W

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WI

="

& r

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)N T%($S 14 S1'ND)N T%($S 14 S1'ND

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# ; lo/ # ; lo/

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D)(%0T)>)T3 )ND%D)(%0T)>)T3 )ND%

D)D)# L# L--@ L@ L-s-s

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B&S)0 P1)NT S1'(0%B&S)0 P1)NT S1'(0%

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%0%SS &TT%N'&T)1N%0%SS &TT%N'&T)1N

&&ee## attenuation b absor-tion in air, dBattenuation b absor-tion in air, dB

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&&ee# attenuation b barriers, dB# attenuation b barriers, dB

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&&e5e5# attenuation b houses, dB# attenuation b houses, dB

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SNA-Davis-Chapter 15 Noise (1)