Noise

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Noise Hearing Conservation

• INSY 5010/6010/6016
• Fall 2006

LG 4
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YOUR EARS HAVE NO PROTECTION

• Noise destroys your hearing little by little.
• Exposure to noise occurs on and off the job.
• Your ears typically recover from exposures to
  low level noises.
• However, permanent damage may occur from even a
  single exposure to very loud noises.

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Noise Effects Us In Other Ways

• Noise is Psychologically Stressful
• Noise may distract our attention and cause
• Accidents, Misunderstandings, Poor Performance,
  Fatigue and General Anxiety.
• NIOSH is studying the health effects of chemical
  exposures (solvents) combined with excessive
  noise exposures.

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Noise

• Any unwanted sound--created by many different
  sources
• Traffic
• Industrial equipment and tools
• Music
• Gunfire exercises
• Ventilation
• Excessive noise--over time and certain
  levels--can cause hearing loss

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Technically What is Noise?

• Energy
• Pressure changes in a medium (air) caused by
  vibration or turbulence
• Pressure produces wave motions from a source
• Amplitude Loudness Decibels dB
• 60 dB Average Speaking Voice
• Frequency Cycles per Second Hertz Hz
• 1000 Hz 1 Kilohertz 1 kHz Human Voice

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Noise at work

• 30 million workers are exposed to harmful levels
• 2nd most reported occupational illness
• Noise-induced hearing loss is irreversible but
  100 preventable

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It is too Loud When ____ ?

• 2-3 foot rule

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Noise Exposure

• Determined by
• Duration of exposure
• Type of noise
• Continuous
• Impulse
• Intensity
• Frequency

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Causes of Hearing Loss

• Age
• Disease (Middle or Inner Ear)
• Trauma
• Drugs
• Noise exposure

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How Hearing Loss Occurs
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Damage to the Ear

• Outer ear--
• Catches dirt and particles in the canal that
  contains wax
• Middle ear--
• Has bones and ear drum which can rupture from
  sudden high sound pressure levels
• Inner ear--
• Has cochlea with tiny hair cells connected to
  nerves. Damage is irreversible

Middle ear
Cochlea
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Human Hearing Ranges

• 20 Hz (low rumble) to 20,000 Hz (whine)
• Speech Between 500 Hz to 2000 Hz
• Average Hearing Loss at 4000 Hz and up
• 0 dB (just audible) to 140 dB (causes pain)
• 80 dB(A) 8 hour TWA will effect some
• 100 dB(A) 8 hour TWA will effect all

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Measuring Sound
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Terminology

• Frequency
• Measured in hertz (Hz) or cycles per second
• Determines how high or low the pitch is
• Intensity
• Measured in decibels (dB)
• Determines how loud a noise sounds

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Other Information

• Ability to hear well depends on
• Pitch of the sound
• Age of the individual
• Distance from noise source
• Previous noise exposures
• Environment (surroundings)

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Other Information

• Sound level meters used to measure noise levels
• 20 Decibels (dB)- faint sound (like a quiet
  bedroom)
• 150 Decibels (dB)- F/A-18 at takeoff on flight
  deck
• Typically, industrial hygienists and safety
  personnel conduct noise surveys

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How is Noise Measured?

• Noise is measured in decibels (dB) at a certain
  scale, such as A or C.
• The decibel scale is logarithmic
• That means, with a 5dB exchange rate, 95 dB is
  100 more noise than 90 dB!

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Hearing Conservation Program
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Program Objective

• The objective of the Hearing Conservation Program
  is to prevent hearing loss as a result of
  exposure to hazardous noise.

How would YOU like to own this?
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Program Elements

• Identifying noise hazardous areas
• Engineering controls to reduce the hazard
• Posting of noise hazardous areas
• Providing hearing protection to personnel
• Medical monitoring (audiograms)
• Education and training
• Recording Requirements

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The Program Elements
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Identifying Noise Hazardous Areas

• Limits for continuous noise exposure
• OSHA 90 dB
• Impact (Impulse) noise limit 140 dB
• 90 dB or less?OK for personnel 8 hours a day,
  five days a week with no ill effects.
• Above 90 dB?Noise is considered hazardous

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Identifying Noise Hazardous Areas

• Sound level surveys conducted to determine which
  spaces routinely have
• Continuous noise gt 85 dB
• Impact noise gt140 dB
• Survey documents retained at establishment
• Readings repeated if new equipment added/changed
• Readings reviewed every 18 months as part of IH
  survey

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Engineering Controls

• Accomplished as part of
• New construction
• Renovation
• Equipment Replacement or repair

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Engineering Controls

• Noise can be decreased by changes in design or
  imposing controls
• Damping material or sound curtains around
  equipment
• Acoustical tiles for classrooms
• Rubber insulating pads at metal-to-metal
  interface
• Moving noise equipment to isolated location
• Engineering controls must be considered FIRST,
  prior to resorting to PPE

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Posting Noise Hazard Signs

• Used when engineering controls do not work, or
  are not feasible
• Use Yellow and Black signs to mark hazards
• Large signs for entire areas
• Small stickers for individual equipment
• Post areas as DOUBLE Hearing Protection Required
  if sound levels gt 105 dB

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Personal Protection

• Used as last resort--when exposures cannot be
  controlled by any other means
• Ear plugs and muffs
• Mechanically block noise from ear
• Rated for specific Noise Reduction Rating
  (NRR)--reduce decibel levels reaching the ear by
  the number listed on the package

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Personal Protection

• Ear plugs
• Fit into ear canal
• Fitted/Flanged types issued by Medical
• Disposable foam plugs dont require fitting--also
  have highest NRR (about 30 dB)
• Ear muffs
• Fit over outer ear
• Have NRR of 24-28 dB
• Ear caps--like plugs with a head band--NRR of
  about 22 dB

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Personal Protection

• Double protection
• Required when continuous sound levels gt 105 dB
• Use combination of ear plugs and ear muffs
• Must be kept clean and in good condition
• Dirty plugs may cause infections
• Muffs with hardened seals DO NOT protect
• Noise Reduction Ratings (NRR) - adjust by the
  following formula (NRR-7)/2

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Real World Reduction (Thumb rules)

• Earmuffs Subtract 25 from the manufacturer's
  labeled NRR
• Formable earplugs Subtract 50 from the
  manufacturer's labeled NRR
• All other earplugs Subtract 70 from the
  manufacturers labeled NRR

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Hearing Protection Selection

• Convenience
• Comfort
• Communication needs
• Hygiene
• Noise Reduction
• Hearing ability
• Noise Level

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Medical Monitoring

• Baseline and routine testing required for all
  personnel working in noise hazardous areas
• Annual audiograms given to personnel assigned
  work in noise hazardous areas
• Termination audiograms given to personnel when
  leaving the company

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Monitoring

• Required where exposure may equal or exceed 85
  dB(A) for an 8 hr TWA
• Measure 8 hr. TWA using
• Calibrated integrating dosimeter
• Remonitor when change occurs or new employee
• Employees may observe the monitoring
• Notify employees of monitoring results

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Audiometric Testing

• Baseline test (within 6 months of exposure)
• Annual audiograms (compared to baseline)
• Performed by certified technician
• Professional supervisor must be a licensed
  audiologist or doctor
• Inform employees in writing of results if
• Abnormal test results
• Standard Threshold Shift (STS) detected

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Comparing Baseline and Annual Audiograms

• Compare latest audiogram with the oldest
• Compute differences of test results at
• 2 kHz, 3 kHz and 4 kHz
• Notify employee within 10 days, of hearing loss
  when gt 10 dB(A), also known as a Standard
  Threshold Shift (STS)
• Retrain employee on hearing protection

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Audiogram Comparison for Mr. I. Ben Listnen

• Right Ear 500 1000 2000 3000 4000 6000
• 9/10/82 10 5 15 10 20
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• 9/16/98 15 20 35 25 45
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• difference 20 15 25
• Average (20 15 25) / 3 60/3 20 dB
• Standard Threshold Shift - YES
• OSHA Recordable - NO

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Employee Training

• Conduct annually on
• Effects of noise on hearing
• Reasons for annual audiograms
• Proper selection, use and care of protectors
• Pros and Cons of various protectors
• Other training may include
• Explanation of audiometric test results
• Methods to control noise

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The Best Ways to Reduce Hearing Loss (in order of
priority)

• Eliminate the source
• Substitute a quieter process
• Engineer sound controls on the source
• Isolate the source by distance
• Shield the source
• Provide sound dampening materials
• Reduce exposure times
• Hearing protective devices (last option)

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The End