Download Noise and Hearing Conservation English

Noise and Hearing
Conservation
Image credit: OSHA
Session Objectives
You will be able to:
• Understand the effects of noise on hearing
• Identify sources of noise in your workplace
• Describe the purpose of audiometric testing
and be able to interpret your test results
• Select, fit, and use hearing protection
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0507
What Is Sound?
• Sound is a longitudinal pressure wave of
energy with the following characteristics:
• Frequency (pitch) measured in hertz (Hz)
• Pressure (loudness) measured in decibels (dB)
• Frequency and pressure of a sound wave
with duration of exposure determine the risk
of hearing loss
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Noise Sources
• Machinery, tools, and
equipment emit sounds
of varying loudness
and in particular
frequencies
• Continuous or
intermittent
• Low-frequency
equipment noise
sources cause hearing
loss in the speech
frequencies
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Sound Pressure Levels of
Common Noises
Noise Source
• Whisper
• Conversation
• Shop tools
• Pneumatic drill
• Woodworking shop
• Abrasive blasting
• Jackhammer
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Loudness
10 dB
65 dB
90 dB
100 dB
110 dB
115 dB
130 dB
OSHA Noise Exposure
Limits
• 90 dBA TWA for 8-hour exposure
• 95 dBA TWA for 4-hour exposure
• 100 dBA TWA for 2-hour exposure
• 105 dBA TWA for 1-hour exposure
• Use engineering controls, administrative
controls, and personal protective equipment
(hearing protection) to meet standards
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Indicators of High Noise
Levels
• Noisy conditions can make normal
conversation difficult
• 80 dB–People have to speak very loudly
• 85-90 dB–People have to shout
• 95 dB–People have to move close together
to hear each other at all
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How Is Noise Hazardous?
• Noise can result in temporary or permanent
hearing loss
• It can cause you to misunderstand
communication
• It can cause you to miss important safety
warnings
• It can create unhealthy stress
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How We Hear Sounds
• Sound waves enter the ear canal
• Eardrum vibrations pass along tiny bones
• Tiny hairlike cells flow back and forth
• The auditory nerve sends signals to the
brain that are registered as sound
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How Hearing Is Damaged
• Hearing ability relies
on delicate parts that
can be damaged in the
inner and middle ear
• Hairlike cells in the
inner ear are flattened
by high noise levels
and injured over time
• Hearing loss is gradual
• Hearing damage is
permanent
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Image Credit: OSHA
Hearing Loss
• Hearing loss is any
reduction in the ability
to hear
• Two types of loss
• Temporary hearing loss
(temporary threshold
shift) may occur
immediately following a
high noise exposure
• Permanent hearing loss
(standard threshold shift)
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Signs of Hearing Loss
• Difficulty hearing
people speak
• Inability to hear certain
high-pitched or soft
sounds
• Noise or ringing in ears
• Getting complaints that
the radio or TV volume
is too high
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Image Credit: Tom Ouimet
Evaluating the Noise
Exposure Hazard
• Conduct a noise
survey
• Identify and characterize
high-noise sources
• Identify impacted
employees
• Monitor impacted
employees
• Repeat monitoring
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Image Credit: Tom Ouimet
Noise Hazards—Any
Questions?
• Any questions about the hazards of
excessive noise and how to identify them?
• Questions about signs and symptoms of
hearing loss?
• Questions about measuring hearing loss?
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Elements of the Hearing
Conservation Program
• All employees exposed to >85 dBA for
8 hours must participate
• You receive:
• Baseline and annual audiograms
• Annual training on hearing loss
• Audiograms and PPE
• Hearing protection is provided
• Exposure assessment conducted
periodically
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Audiometric Exams
• Exams can detect early signs of hearing
loss
• Typically measures hearing threshold at six
frequencies
• Hearing thresholds are compared with
previous audiograms
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Standard Threshold Shift
(STS)
• Hearing loss has occurred if you have
experienced a standard threshold shift
(STS)
• Hearing ability changed by an average
of 10 dB
• Revised hearing protection required for
STS
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Has an STS Occurred?
Baseline
Annual
Image Credit: Tom Ouimet
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An Example of Hearing
Loss in Carpenters
Image Credit: Tom Ouimet
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Hearing Protection Use
• Voluntary use if exposed to an 8-hour TWA
of 85-90 dB
• Mandatory use when:
• Exposed to an 8-hour TWA of 90 dB
• Exposed to an 8-hour TWA of 85 dB and have
suffered an STS (hearing loss) or have not had a
baseline hearing test
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Hearing Protection Devices
Noise Reduction
• Hearing protection devices must reduce
employee noise exposure below an 8-hour
TWA of 90 dB
• Employees with STS, noise exposure
reduced below an 8-hour TWA of 85 dB
• Noise reduction ratio (NRR)
• Earplugs: use 1/3 of NRR
• Earmuffs: use 1/2 of NRR
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Hearing Protection Devices—
Earplugs and Canal Caps
• Must be properly
inserted to seal the ear
canal
• Slowly roll and compress
foam into cylinder
• Insert into ear canal while
compressed
• Keeps noise from
reaching the eardrum
• Cotton is not an
earplug
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Image Credit: State of WA-WISHA Services
Hearing Protection
Devices—Earmuffs
• Sealed against head
•
•
•
•
with ears fully enclosed
Hair out from muffs
Glasses and caps do
not interfere with seal
Headband adjusted so
cushions exert even
pressure
Cleaned with warm,
soapy water and rinsed
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Any Questions?
• Any questions about audiometric testing?
• Questions about our hearing protection
program?
• About when to use hearing protection?
• About hearing protection devices?
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Key Things to Remember
• Hearing is a very important sense – don’t
lose it
• Noise exposure over 85 dB can cause
hearing loss
• Hearing loss cannot be cured or repaired
• Hearing tests are conducted annually and
can detect hearing loss
• Hearing protection devices must be worn in
high-noise areas
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0507