OSHA Occupational Noise

San Diego State University

Environmental Health and Safety
Millie Tran and Sheryl Mansour
 Can You Imagine?
• Not being able to
– Hear what the other person is saying?
– Listen to the sound of music?
– Listen to the sound of nature?

• Being afflicted with

– Uncomfortable ringing in your ears?
– Abnormal sounds that interfere with your sleep?
Noise Permissible Exposure Limits
(PEL)
• Utilize administrative or engineering controls
when sound levels exceed Noise
Permissible Exposure Levels (Table N-1),
e.g. 8 hours permitted duration per workday
for 90 dBA sound level.
• Provide hearing protectors if above controls
fail to reduce sound levels within Permissible
Exposure Levels (Table N-1).
• Impulsive or impact noise should not exceed
140 dB.
 Hearing Conservation Program
(HCP)
• implemented whenever employee noise
exposures equal or exceed and 8-hour
time-weighted average (TWA) of 85
dBA without attenuation from use of
hearing protectors.
 Training
• Noise Monitoring
• Elements of HCP • Noise Map (area noise level)
• HCP Flow Chart • Noise Dose (personal occupational noise
exposure level)
• Sound Pressure Level Concepts and
Terms • Table of Permissible Noise Exposure Limits
• Anatomy and Physiology of Normal • Impulsive or Impact Noise
Ear • Noise Control
• How We Hear Sounds • Administrative Controls
• Effects of Noise on Hearing • Engineering Controls
• Symptoms of Overexposure to Noise • Hearing Protectors
• Anatomy and Physiology of Damaged • Purpose of Hearing Protectors
Ear • Advantages and Disadvantages of
• How Hearing is Damaged Different Types of Hearing Protectors
• Signs of Hearing Loss • Attenuation of Different Types of Hearing
• Types of Hearing Loss Protectors
• Noise Induced Hearing Loss • Instructions on Selection, Fitting, Use,
and Care of Hearing Protectors
• Occupational/Non-occupational
Hearing Loss • Audiometric Testing
• Statistics on Occupational Hearing • Purpose of Audiometric Testing
Loss • Evaluation of Audiogram
• Types of Noise • Audiometric Test Requirement
• Recognizing Hazardous Noise • Explanation of Test Procedures
• Audiometer Calibration
• Training
• Record Keeping
 Rule of Thumb
When you feel the need to
shout in order to be heard
3 feet away, the noise levels
are probably 85 dB or more
and hearing protectors are
recommended.
 Elements of Hearing Conservation
Program
• Noise Monitoring
• Hearing Protectors
• Audiometric Testing
• Evaluation of Audiogram
• Audiometric Test Requirements
• Audiometer Calibration
• Training
• Record Keeping
 HCP Flow Chart
• Pre-employment Test
• Noise Map (area noise – sound level meter)
• Occupational Noise Exposure (personal noise – noise
dosimeter)
• Noise Dose
– > 100% - noise control – engr. ctrl.; otherwise ppe
– < 100% - audiometric test
• Engr. Ctrl. / PPE – audiometric test
• Audiometric Test – noise induced hearing loss
– Yes – utilize noise control
– No – continue audiometric test
• Training
• Record Keeping
 Sound Pressure Level
• Sound waves are energy produced by
vibrating objects
• The larynx vibrates to produce the voice
• The vibrations create a pattern, which the
ear translates into sound
• As you double the distance from a noise
source, the source loudness decreases by
half
• Strong vibrations from very loud noises
can damage the ear
 Anatomy and Physiology of
Normal Ear

Stapes Semicircular Canals

Auditory Nerve
Ear Canal

Cochlea

Ossicles

Ear Drum Eustachian Tube

 How We Hear Sounds
• Sound waves enter the ear canal striking the
eardrum.
• When eardrum vibrates, ossicles conducts
vibrations to the cochlea.
• Tiny hairlike cells in cochlea respond to
vibrations by generating nerve impulses.
• Brain interprets nerve impulses as sound.

Note: Healthy hair cells are the key to good

hearing. Although, some die off naturally as you
age, many more are killed early, from
unprotected exposure to hazardous noise.
 Effects of Noise on Hearing
Note: How quickly hearing loss takes place
depends on the intensity of the noise, its
duration, and how often the exposure
occurs.
 Symptoms of Overexposure to
Noise
• Temporary Threshold Shift
– muffled sound after noise exposure
– if continued overexposure, shift can worsen and
become permanent
– resulting in untreatable damage to hearing
• Tinnitus
– ringing in the head when trying to sleep at night
– if continued overexposure, ringing can become
permanent, constant annoyance
Anatomy and Physiology of
Healthy Ear
Anatomy and Physiology of
Damaged Ear
Anatomy and Physiology of
Damaged Ear
 How Hearing is Damaged
• Hairlike cells are flattened.
• You do not get used to noise; you
gradually loose your hearing
• Once haring is damaged, it cannot be
repaired or replaced.
 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 is too loud.
 Types of Hearing Loss
• Conductive
– Sound is not conducted from outer ear to inner ear
– Reduction in sound level
– Condition results from fluid in middle ear, foreign bodies, infection in
ear canal, impacted ear wax, malformation of ear
• Sensorineural
– Results from damage to the inner ear or nerve pathways from ear to
brain
– Corrected through surgery
– Caused by birth injury, diseases, noise exposure, head trauma, aging
• Mixed
– Hearing loss resulting from both conductive and sensorineural
 Noise Induced Hearing Loss
Noise induced hearing loss stems from exposure
to loud noises.
• Constant exposure over a period of time
• Exposed to sound level over 140 dBA
• Tinnitus

Age Induced Hearing loss

• Exposure to high sound levels
• Hereditary
• Nerve damage
• Reduced neuronal response
 Occupational/Non-Occupational
Hearing Loss
• Occupational Hearing Loss
– Results from constant exposure to sound levels
above 85 dBA TWA
– Damage to hair cells in cochlea
• Non-Occupational Hearing Loss
– Results from constant exposure to sound levels
above 85 dBA TWA
– Results from damage to outer, middle, or inner ear,
hereditary, ototoxic drugs
– Damage to hair cells in cochlea, damage to nerve
cells relaying sound message to brain, damage to
structure of ear
 Statistics on
Occupational Hearing Loss
Approximately 30 million Americans are
exposed to high intensity noise in their
workplace.
One in 4 of these workers (or 7.5 million
Americans) will develop permanent
hearing loss.

National Institute of Deafness and Other Communicative Disorders: Noise Induced

Hearing Loss. Available
at: http://www.nidcd.nih.gov/health/hearing/noise.asp Accessed November 7, 2004.
 Effects of Age and Noise on
Hearing
Normal Aging Effects Loss from Aging plus
95dB Noise Expsoure
-10
-10
Hearing Threshold

Hearing Threshold Level dB

0
10 10
Level dB

20 20
30 30
40 40
50 50
60 60
70 70
500 1000 2000 3000 4000 6000 500 1000 2000 3000 4000 6000
Frequency Hz
Frequency Hz
40 yrs.exp. 20 yrs.exp.
age 60 age 40 age 20 10 yrs.exp. 0 yrs.exp
 Types of Noise
• Pitch
• Loudness
– Whisper 10 dB
– Street sound 70 dB
– Sander 85 dB
– Sporting Events 100dB
– Mowing the Lawn 101dB
– Motorcycle Riding 112dB
– Concerts 125dB
– Shooting Range 130dB
 Recognizing Occupational
Hazardous Noise
Task Avg. Noise Level Tools Avg. Noise Level
(dBA) (dBA)
Operating forklift 87 Lathe 81
Cutting Wood 93 Welding 94.9
Equipment
Cutting lawn 94
Hand Power Saw 97.2
Installing trench 95.8
conduit Screw Gun, Drill 97.7
Welding 98.4 Rotohammer 97.8
Grinding 99.7 Chop saw 98.4
Chipping 102.9 Stationary Power 101.8
Concrete tool
Working near 116 Chipping Gun 103.0
Generator
 Recognizing Non-Occupational
Hazardous Noise
• Noisy Hobbies
– Loud music
– Firearms
– Car/motorcycle race track
– Sporting events
– Loud speakers

• Household noises
– Crying babies
– Vacuum
– Lawn mower
– Power tools
– Ipod/Boom box
 Noise Monitoring
• Used to identify work locations
where hazardous noise levels exits.
• Employee exposures to noise
monitored periodically with:
– Sound Level Meter (area noise level)
– Noise Dosimeter (personal noise
exposure level)
Noise Map (Area Monitoring)
Noise Dose (Personal Monitoring)
 Table of Permissible Noise
Exposure Limits
Sound Level Permitted Duration per Sound Level Permitted Duration per
(dBA) Workday (hours) (dBA) Workday (hours)
90 8.00 103 1.32
91 6.96 104 1.15
92 6.06 105 1.00
93 5.28 106 0.86
94 4.60 107 0.76
95 4.00 108 0.66
96 3.48 109 0.56
97 3.03 110 0.50
98 2.63 111 0.43
99 2.30 112 0.38
100 2.00 113 0.33
101 1.73 114 0.28
102 1.52 115 0.25
 Impulsive or Impact Noise
• Exposure to impulsive
or impact noise
should not exceed
140 dB peak sound
pressure level.
 Affected Employees
• Employees subjected to noise exceeding
permissible noise limits shall be provided
hearing protection devices, if feasible
administrative or engineering controls failed to
reduce noise levels.

• Employee exposed to noise at or above the 8-

hour time-weighted average (TWA) of 85 dB, or
equivalently, a dose of 50% shall be notified and
enrolled in HCP.
 Noise Control
• Administrative Control
• Engineering Control
• Personal Protective Equipment ( hearing
protective devices)
 Administrative Controls
• Operate noisy equipment on second or
third shifts.
• Rotate employees through high-noise
areas.
• Modify existing machinery.
• Place noise limit specs. on new equip.
• Maintain equip. in good condition.
• Use noise control when installed.
• Reporting noisy equip. to supervisor for
repair.
 Engineering Controls
• Reduce noise at the source.
• Interrupt the noise path.
• Reduce reverberation and structural
vibration.
 Personal Protective Equipment
(Hearing Protection Devices - HPD)
• Employers shall provide to employees
exposed to 8 hr TWA of 85 dB at no cost.
• Employers shall ensure being worn:
– by employees exposed to 8 hr TWA of 90dB
or greater
– by employees exposed to 8 hr TWA of 85dB
or greater and:
• Whose baseline audiogram has not been
established
• Who have experienced a threshold shift
 Hearing Protection Device (HPD)
Noise Reduction
• HPD must reduce employee noise exposure
below PEL e.g. below 8 hr TWA of 90 dB.
• Employees with standard threshold shift (STS),
HPD must reduce employees noise exposure
below an 8 hr TWA of 85 dB.
• Noise Reduction Ratio (NRR)
1. Convert dose to TWA; subtract 7 from NRR;
subtract remainder from TWA to obtain the est.TWA
under ear protector
2. Subtract 7 from NRR; subtract remainder from TWA
to obtain the est. TWA under ear protector
 Hearing Protection Use
• Voluntary Use
– Exposed to an 8 hr TWA of 85 dB
• Mandatory Use
– Exposed to an 8 hr TWA of 90 dB
– Exposed to an 8 hr TWA of 85 dB but have
not had a baseline hearing test
– Employees who have suffered STS hearing
loss and are exposed to an 8 hr TWA of 85 dB
 Employee Responsibility
• Understand the need for hearing
protection devices.
• Wear HPDs and seek replacements.
• Encourage co-workers to wear HPDs.
• Communicate problems to supervisors.
 Management Responsibility
• Provide occupational noise training.
• Provide hearing protection devices.
• Demonstrate commitment – wear HPDs.
• Enforce the use of HPDs.
• Keep up to date with HPD selection and
use.
• Encourage questions and resolve
problems.
 Purpose of Hearing Protectors
• Reduction of sound waves traveling to the
inner ear
 Advantages and Disadvantages of
Different Types of Hearing Protectors
Kind of Protector Advantages Disadvantages
Ear Plug •Free head movements •Can work loose during the
•Good for tight work work day
spaces •Must be replaced
•Worn with any hairstyle periodically
•Worn with hats, eye •Small and can easily be
protection, respirators lost
•Good protection against
high frequency sounds
Ear Muff •Headband can be •Difficult to wear with eye,
adjusted for comfort head and breathing
•Seldom come loose protection
during the work day
•Free head movements
 Attenuation of Different Types of
Hearing Protectors
• Ear Plugs
– Reduce noise by as much as 30 decibels
• Ear Canals
– Reduce noise by as much as 30 decibels
– Used when individual is unable to use traditional ear
plugs
• Ear Muffs
– Reduce noise by as much as 15-30 decibels
– Use in conjunction with ear plugs when exposed to
high noise levels (105+ decibels)
 Instructions on Selection, Fitting,
Use, and Care of Hearing Protectors
Ear plugs
– Keep clean and free of materials
• Wash in mild liquid detergent and warm water
• Squeeze excess water and air dry
– Discard plugs when hardened or do not re-
expand
• Ear Canals
– Clean like normal ear plugs
– Do not tamper with the headband and the
acoustic seal
 Instructions on Selection, Fitting,
Use, and Care of Hearing
Protectors
• Ear Muffs
– Keep clean and free of debris
• Clean cushions with warm soapy water
– Do not tamper with the acoustic seal between
the cushions and the headband
– Do not modify the ear muffs in any way
– Do not stretch or abuse the headband
 Audiometric Testing
• Conducted by a qualified audiologist.
• Baseline Audiogram/Test
– Shows initial hearing status
– For comparison to future audiograms
• Periodic (Annual) Audiogram/Test
– To determine if HCP is effective and if non-
noise factors affects hearing
– Recheck audiogram or professional referral
necessary if significant hearing change occurs
Purpose of Audiometric Testing
• To measure hearing by sending tones to
each ear through headphones.
• To show how one’s hearing compares to
normal hearing based on age.
• To determine whether hearing is being
conserved.
• To alert employee and employer for noise,
age or medical related hearing loss.
 Explanation of Test Procedures
• Audiometer sends tones to each ear
through headphones.
• Listen carefully and respond each time
you hear a tone.
• Levels at which you can barely hear the
tones is your hearing threshold levels.
• Audiogram records threshold (dB) for
different pitches or frequencies (Hertz).
 Evaluation of Audiogram
• Annual audiogram compared to baseline audiogram to
determine threshold shift
• If threshold shift
– Employee must be notified in writing within 21 days
• If threshold shift from occ. noise exp.
– Employee fitted with hearing protectors, trained in use and care,
required to use them.
– Employee refitted with better attenuation hearing protectors and
retrained in hearing protector use
– Refer employee to eval/exam if add. testing necessary or if
medical pathology is caused by hearing protectors
– Inform employee of need to eval/exam if medical pathology
unrelated to hearing protectors is suspected
Evaluation of Audiogram (con’t)
• If subsequent audiogram to noise exp.
less than 8 hr TWA of 90dBA indicates
that threshold shift is not persistant:
– Inform employee of new audiogram
– May discontinue required use of hearing
protectors
 Normal Audiogram and Degree of Hearing Loss

-10
H earin g T h resh o ld L evel

0 Normal Hearing
10
20
30 Mild Hearing Loss
40
dB

50 Moderate Hearing Loss

60
70 Severe Hearing Loss
80
90 Profound Hearing Loss
100
500 1000 2000 3000 4000 6000

Frequency, Hz (low pitched to high pitched sounds)

 Standard Threshold Shift
• Hearing ability changed by an average of
10 decibels.
• Employee notification within 21 days.
• Revised hearing protection required.
• Further medical evaluation.
• Allowance may be made for the
contribution of aging.
Audiometric Test Requirements
• Test shall be pure tone, air conduction,
hearing threshold exam.
• Test frequencies from 500 to 6000 Hz in
each ear.
• Audiometers shall meet ANSI S3.6 and
Appendix B
• Audiometric exams administered in room
shall meet Appendix C
 Audiometer Calibration
• Audiometer functional operation shall be
checked daily.
• Audiometer calibration shall be checked
acoustically annually per Appendix D
 Training
• Provide annually to employees who are exposed
to noise at or above 8 hr TWA of 85 dB.
• Topics must include:
– Effects of Noise on Hearing
– Purpose of Hearing Protectors
– Advantages and Disadvantages of Different Types of
Hearing Protectors
– Attenuation of Different Types of Hearing Protectors
– Instructions on Selection, Fitting, Use, and Care of
Hearing Protectors
– Purpose of Audiometric Testing
 Record Keeping
• Employee Exposure Measurements
• Audiometric Tests
– Audiogram/Noise Exposure Assessment
– Job classification
– Audiometer calibration date
• Hearing Protection Devices Used
• Audiometric Test Rooms
– Background sound pressure level in test room
 Summary
• Constant exposure to noise over 85 dB
can cause hearing damage.
• Hearing loss can not be cured or repaired.
• Hearing tests are conducted annually.
• Hearing protection devices include ear
plugs, ear muffs, and canal caps.
 QUIZ
1. Employee participation in the Hearing
Conservation Program is required when
exposed to an 8 hr TWA noise level of ____
decibels.
2. Hearing damage can easily be repaired with
surgery. True or False
3. Describe a sign of hearing loss: _______
4. Name two off-work activities that may expose
you to high-noise levels.
5. Your company keeps records of noise
monitoring and hearing tests. True or False
 QUIZ
6. A noise dosimeter is used to test an
employee’s hearing capability. True or False
7. Describe one of the ways noise impacts the
workplace. ____________________________
8. Name two kinds of hearing protection devices:
_______________ and __________________
9. In order to look for hearing loss, how often are
hearing tests conducted? ________________
10. Name one of the ways management attempts
to control employee noise exposure:
_____________________________________