noise and hearing conservation
DESCRIPTION
Noise and Hearing ConservationTRANSCRIPT
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Session ObjectivesYou 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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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 ofCommon Noises Noise Source Loudness• Whisper 10 dB• Conversation 65 dB• Shop tools 90 dB• Pneumatic drill 100 dB• Woodworking shop 110 dB• Abrasive blasting 115 dB• Jackhammer 130 dB
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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
permanentImage Credit: OSHA
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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
Image Credit: Tom Ouimet
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Evaluating the Noise Exposure Hazard• Conduct a noise
survey• Identify and characterize
high-noise sources• Identify impacted
employees
• Monitor impacted employees
• Repeat monitoringImage Credit: Tom Ouimet
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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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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
Image Credit: State of WA-WISHA Services
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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?