Noise: Health Effects, Measurements, & Controls · 2019. 2. 26. · AIHA: The Occupational Environment: Its Evaluation, Control, and Management, 3rd edition. DEMO Noise Source Addition

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Noise: Health Effects, Measurements, & Controls

2019 Indiana Safety & Health Conference

9:00 a.m. ‐ 12:00 p.m.February 26, 2019

©2019, A Havics 1

Andrew A. “Tony” Havics, CIH, PEpH2, LLC

Decibel Hell

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Which would you choose to “keep” if for the rest of your life you could only have one of your two senses – your hearing or your vision?

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“…after a lifetime in silence and darkness that to be deaf is a greater affliction than to be blind…I have imagination, the power of association, the sense of touch, smell, and taste, and I never feel blind, but how can I replace the loss of hearing?”

‐ Helen Adams Keller (1880‐1968)

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Some Facts

• 75% of farm workers have some hearing loss

– Source: NY Center for Agriculture and Medicine

• The sound system in your car is louder than the sound system the Beetles used for their concerts in the 1960s. They only had 300 Amp speakers.

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Anatomy & Hearing

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The Ear

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The Occupational Environment – It’s Evaluation and Control, 3rd Ed., D. Anna, Editor, American Industrial Hygiene Assoc. Press, Fairfax, VA, 2011.

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Sound & Noise Fundamentals

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General Waveform Explanation

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Sound moves about 340 m/s

Wave definitions

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Air at Sea Level


DON’T PANIC ‐ YET

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Typical Sound Variation

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Frequency

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The human hears approximately 20 Hz to 10,000 Hz

Q: What is Hertz?

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Wavelength of Sound in the Air

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Frequency (Hz) Wavelength

31.5 35.8 ft

63 17.9

125 9.0

250 4.5

500 2.2

1000 1.1

2000 6.7 in

4000 3.4

8000 1.7

Speed of Sound

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Material Speed (fps)

Air 1,100

Lead 4,000

Water 4,500

Concrete 10,000

Glass 12,400

Wood 14,000

Steel 17,000

Iron 17,000

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Sound Pressure Level

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Q: How many Pascals is Ambient Air Pressure?

Perceived Loudness

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A‐, B‐, C‐Weighting Scales

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C W e ig h tin gB W e ig h tin gA W e ig th in g

10 100 1,000 10,000

F re q ue nc y (Hz)

-80

-70

-60

-50

-40

-30

-20

-10

0

10

Re

lativ

e R

esp

onse

(dB

)

Typical Values for SPL

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Speech Interference

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OSHA PEL

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OSHA PEL

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5 dB 2X

5 dB 2X

Exchange Rate = 5 dB


Level v. Dose

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Dose Example: Eng/Admin Controls

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D = C1 + C2 + C3 ……. Cn

T1 T2 T3 ……. TnX 100, percent

D = 4 + 2 + 2

4 4 8X 100, percent

D = (0 + 0.5 + 0.25) X 100 = 75%

80 dBA for 4 hours95 dBA for 2 hours90 dBA for 2 hours

D = DoseC = Amount of time exposed at specified noise levelT = Amount of time allowed at specified noise level

0

See Handout Also

A‐Weighting for All Limits

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C W e ig h tin gB W e ig h tin gA W e ig th in g

10 100 1,000 10,000

F re q ue nc y (Hz)

-80

-70

-60

-50

-40

-30

-20

-10

0

10

Re

lativ

e R

esp

onse

(dB

)

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TWA Calculation

• A dose of 1.0 (100%) is equivalent to a time‐weighted average (TWA) of 90 dBA.

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TWA Calculation Example

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TWA = 16.61 Log10[D/100] + 90

TWA = 16.61 Log10[75/100] + 90

TWA = 16.61 Log10[0.75] + 90

TWA = 16.61 [‐0.12494] + 90

TWA = ‐2.08 + 90

TWA = 87.92

87.92 < PEL of 90 dBA so OK

Previous Example ‐ D = (0 + 0.5 + 0.25) X 100 = 75%

See Handout Also

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©2019, A Havics 29The Occupational Environment – It’s Evaluation and Control, 3rd Ed., D. Anna, Editor, American Industrial Hygiene Assoc. Press, Fairfax, VA, 2011.

What about Determining Time for Other Limits?

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TSPL = 8/(2(L‐Th)/ER) hours

Where:

TSPL = Time allowed at a Sound Pressure Level LL = SPL of noise for that time periodTh = Threshold LimitER = Exchange Rate

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NIOSH REL

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TSPL = 8/(2(L‐Th)/ER) hours

Where:

TSPL = ??L = 90 dBATh = 85 dbAER = 3 dBA

TSPL = 8/(2(90‐85)/3) hours

TSPL = 8/(2(5/3)) hours

TSPL = 8/(3.31748) hours

TSPL = 2.41 hours = 145 min

One is allowed 90 dBA for 480 minute for OSHA; What is it for NIOSH?

Different Exposure Limits in Perspective

OSHANavyACGIH, NIOSH, Air Force, Army

050

0

1,00

0

1,500

2,00

0

2,50

0

Allowable Time (min)

70

80

90

100

110

120

130

140

150

SP

L (

dB

A)

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Health Effects & NIHL

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Adverse Effects on Man

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Speech

Speech Interference

• Speech Interference Level (PSIL)

• PSIL = Avg SPL for 500, 1000, and 2000 Hz

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Wilson, Noise Control, 1989

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Sleep Interference

• Noise Exposure Forecast (NEF)

• LDN = NEF + 35 dBA

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Wilson, Noise Control, 1989

Learning Interference

• Aircraft noise

• Train noise

• Traffic and street noise

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Shield, The effects of noise on children at school, a review, J Bldg Acoustics, 10, 2, 97‐106, 2003.Haines, Chronic aircraft noise exposure, stress responses, mental health and cognitive performance in school children, Pyschol Med, 31, 2, 365‐277, 2001

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Measuring NIHL

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Normal Audiogram

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Plogg, Barbara, and Patricia Quinlan, Eds.: Fundamentals of Industrial Hygiene, 5th Edition. National Safety Council, Itasca, IL. 2002.

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Typical Hearing Loss Audiograms

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Early Loss

Intermediate Loss

Advanced Loss

Plogg, Barbara, and Patricia Quinlan, Eds.: Fundamentals of Industrial Hygiene, 5th Edition. National Safety Council, Itasca, IL. 2002.

Threshold Shift

• (10) Standard threshold shift. (i) As used in this section, a standard threshold shift is a change in hearing threshold relative to the baseline audiogram of an average of 10 dB or more at 2000, 3000, and 4000 Hz in either ear

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DEMO

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Noise Induced Hearing Loss (NIHL)

• Noise‐Induced Temporary Threshold Shift (NITTS)– a decrease in hearing sensitivity that typically returns to its former level within a few minutes to a few hours

• Noise‐Induced Permanent Threshold Shift (NIPTS)– irreversible sensorineural hearing loss

• Tinnitus

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Hearing Impairment Threshold

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% Excess Risk of HL%Total Risk of HL

70 80 90 100 110

8-Hr TWA SPL (dBA)

0

10

20

30

40

50

60

70

80

90

100

Ris

k of

Hea

ring

Loss

(%)

Based on data from: Prince, A re‐examination of risk estimates from the NIOSH Occupational Noise and Hearing Survey (ONHS), J Acoust Soc Am, 101, 2, 950‐963, 1997

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Hearing Protection

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Hearing Protection

• Use:

– When engineering controls can’t reduce noise enough

– For employees with noted hearing loss

– While engineering controls are being implemented

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Hearing Protection Devices (HPDs)

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Lab v Reality

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Not Wearing All The Time

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Noise Measurement

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Noise Source Addition

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AIHA: The Occupational Environment: Its Evaluation, Control, and Management, 3rd edition.

DEMO

Noise Source Addition

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0 2 4 6 8 10 12 14 16 18 20

Source Difference (dB)

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

Am

ount

Ad

ded

to H

igh

er S

ourc

e (d

B)

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Noise Source Addition Example 1

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One Source to 85 dBA

Source Controlled Controlled Controlled

Lp Lp Lp Lp

90 85 90 90

90 90 90 90

90 90 90 90

90 90 90 90

93 93 85 93

95 95 95 85

Added Source Sound

99.62 99.28 98.74 98.00

93

95

96

98

100

+2

+3

+1

+2

+2

Noise Source Addition Example 2

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Two Sources to 85 dBA

Source Controlled Controlled Controlled

Lp Lp Lp Lp

90 85 90 85

90 85 90 90

90 90 90 90

90 90 85 90

93 93 85 85

95 95 95 85

Added Source Sound

99.62 98.92 98.32 95.96

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Octave Bands

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1/3 Octave Bands

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Commonly Used

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1/1 v 1/3 Octave Bands

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Sound Levels Meters (SLMs)

• Sound level meters used by OSHA meet American National Standards Institute (ANSI)– Standard S1.4‐1971 (R1976) or S1.4‐1983, "Specifications for Sound Level Meters."

• Types 0, 1, and 2.– Type 0 is used in laboratories.

– Type 1 is used for precision measurements in the field.

– Type 2 is used for general purpose measurements

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Sound Levels Meters (SLMs)

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ANSI S1.4‐1983

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Meter Response Time

• Fast response

• corresponds to a 125‐millisecond (ms) time constant.

• Slow response

• corresponds to a 1‐second time constant

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Dosimetry

• On the Person

– Microphone near Lapel

– OSHA defines the hearing zone as a 2‐foot‐wide sphere surrounding the head

• Criterion Setups

– single or multiple

• Batteries last 8‐10 hours

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Typical OSHA Setup

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Selection Setting forHearing

Conservation

Setting forAdministrative and

Engineering Controls

Threshold 80 dBA 90 dBA

Criterion Level 90 dBA 90 dBA

Exchange Rate 5 dB 5 dB

Frequency Weighting A A

Response Rate Slow Slow

Peak Threshold 140 dBA 140 dBA

Limit 85 dBA AL 90 dBA PEL

Microphone

• Protect from wind and harsh materials

• Wind screens are optional indoors if air currents are minimal

• Always use a windscreen in areas with air motion, outdoors, and in dusty locations or during jobs when the microphone might get dirty

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Similar for SLM

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SPL vs Distance

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Calibration

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Calibration

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Meter Specifics

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Noise Control

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Principle 1 ‐ Identify Sources of Noise and Their Importance

• Sound is Generated by:

– Vibrating surfaces: panels, pipes, etc.

– Mechanical impacts: presses, dropped parts, etc.

– Pulsating gas flows: exhausts

– Air flow over surfaces: ducts, wind, etc.

– Compression & rarefaction of medium: gears mashing, blade passage frequency, etc.

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DEMO

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• Obtain frequency spectrum

• Turn components on & off

• Use temporary controls (mufflers, lagging, enclosures)

• Conduct near‐field readings

• Measure vibration spectrum

• Plot frequency data to observe possible BPF, gear meshing, etc.

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Driscoll, AIHA PDC 431, Noise Control Engineering, 1999

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• Prioritizing for Noise Control:

– Plot linear versus A‐weighted

– Rank noise order sources (dBA)

– Determine interrelationship between noise source and receiver

– Consider benefit to employees in the area

– Consider Noise Criteria

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Variable Speed Fan (at Maximum): A‐Weighted v Linear

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A-WeightedLinear

8 16 32 64 128

256

512

1,024

2,048

4,096

8,192

16,38

4

32,76

8

Frequency (Hz)

-50

0

50

100

SP

L (d

B)

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Rank Order

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Blower

Elect

ric M

otor

Gea

rbox

Pipel

ine

Pump

Equipment Type

50

70

90

110

SP

L (d

BA

) 85.081.0

88.0

95.091.0

Principle 2 – List & Evaluate Possible Noise Control Procedures as they Apply to Source, Path and Receiver

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Possible noise control procedures for:

Source Path Receiver

Modify Enclosure Enclosure

Redesign Absorption Absorption

Relocate Barrier Relocate

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Treatment at Source:

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Treatment of Sound Path:

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liadur.czNewWell

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Treatment of Receiver:

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http://www.iac‐acoustics.com/us/soundproof‐rooms‐and‐booths/medical/audiology‐booths/

Principle 3 – Identify Relative Contributions for Direct and Reflected

Sound

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Total Sound Level = Direct + Reflected

Direct & Reverberant

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Principle 4

• Sound Absorption– is realized by materials, usually porous, which dissipate acoustic energy in the form of heat

– light weight fibrous or foam material

• Sound Isolation– is realized by materials that are poor transmitters

– dense, heavy

• See EAR DEMOs

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Principle 5 – Identify the Significance of Flanking Paths

• Flanking path

– any route by which sound waves travel from a source to a receiver

– airborne or structure‐borne

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DEMO

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Effect of Opening Size

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10% opening

1% opening

0.1% openingApprox. 38‐29 = 9 dB

0.1%

1 SFout of 1,000 SF

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Effect of Distance on Noise

Free-field presumption

0 10 20 30 40 50 60Distance from Sound Source (feet)

75

80

85

90

95

100

105

SP

L (

dB

A)

100 dBA at 5 ft from source

SPLd2 = SPLd1 + 20 Log [d1/d2]

6 dBA

6 dBA

6 dBA

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Total Sound

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Absorption

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Absorption

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Room Effect

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2,0001,0005002001005020105

TA

0.12

5

0.25

0

0.50

0

1.00

0

2.00

0

4.00

0

8.00

0

16.0

00

32.0

00

64.0

00

r/Q (r in feet)

-30

-20

-10

0

10

Lp -

Lw

(dB

)

Direct

Reverberant/Room Effect

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Q‐Factor

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DEMO

Compressed Air

• SPL % (speed)8

• So reduce air speed as low as possible

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Electric Motors

• If an enclosure is used, increase number of blades

• Higher BPF making wavelengths shorter & frequency higher –thus easier to control

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Questions?

©2019, A Havics 94

Andrew Anthony “Tony” Havics, PE

pH2, LLC

5250 E US Highway 36, Suite 830

Avon, IN 46123

(317) 718‐7020 Office

[email protected]

Noise: Health Effects, Measurements, & Controls · 2019. 2. 26. · AIHA: The Occupational Environment: Its Evaluation, Control, and Management, 3rd edition. DEMO Noise Source Addition

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