hearing conservation

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  1. what percentage of work force is exposed to excessive noise
  2. what is hearing impairment consider as? what db
    • at 25 db
    • risk at 80 dba= 3%
    • at 85 dba=15%
    • at 90dba=29%
  3. what is hearing impairment dependent on
    • how the hearing loss is calculated
    • the level of noise exposure
    • number of years of exposure
  4. additional factors in determination of hearing loss
    • function of age other than nihl
    • importance of differentiating general risk from excessive risk
  5. what is excess risk as defined by national institute for occupational safety and health
    as a % with material hearing impairment in a noise pop after subtracting the % who would normally incur such impairment from other causes in non exposed pop
  6. when did NIOSH recalculate risk
    • in 1997 based on its occupational noise and hearing survey conducted from 1968 to 1971
    • recalc was necessary because of the porlific use of  hearing protection begun in early 1980s which would confound a determination of dose response relationships for contemporary workers
  7. noteworthy differences of niosh recalc
    • 1. considers non linear efects of noise
    • 2. uses the definition of hearing handicap as proposed by asha which is the average hearing loss at 1, 2, 3 and 4 with a 25 db low fence
  8. what are the auditory and non auditory effects of hearing loss
    • hearing loss
    • effects on a person's well being
  9. non aud effects include
    • annoyance
    • sleep disturbances
    • speech effects
  10. physiological effects of non aud effects
    • higher heart rate
    •  change in resp pattern
    • chages in blood chem
    • causes stress
    • muscle response
  11. psychological effects of non aud
    • affects human performance
    • reduces ability to focus
    • fine motor skills
    • concentration
    • annoyance, irritalility
    • reduces muscular precision
  12. what additional issues can affect hearing loss
    • smoking
    • certain cancer drugs
    • airborne toxins 
    • hl is variable
  13. speech communication
    • use of articulation index which shows what you should be hearing
    •     percentage of speech components that are audible
    • speech interference level (SIL) METHOD
    •     acceptability of background noise
  14. how is SIL determined
    • using octave band sound level meter
    • vocal effort
    • avg sound pressure level over 500, 1000, 2000 and 4000
  15. at what background noise speech interference level will speech communication be affected
    • at a distance beyond 6-9 feet
    • 6 = normal com
    • 9 = forced com
  16. what is the dba criterion for day and night
    • 55 for day 
    • 45 for night
  17. acoustic trauma
    • a single high intensity noise event such as an explosion
    • impulsive, high intensity noise causes mechanical damage
    • outer hair cells distorted immediately
    • middle ear changes may occur with perforated tm or ossicles dislocated
  18. noise induced hearing loss
    • nihl
    • repeated exposure to moderately high intensity noise
    • insidious nature of nihl
    • physiochemical damage
    • tinnitus and muffled hearing after exposure are warning signs
    • 4 notch on audiogram
  19. when will tts recover
    • temporary threshold shift will recover in 12-16 hours post exposure
    • need to have that time 12-16 filled with effective quiet below 75 dba
  20. where do you usually see notches that indicate a hearing loss
    • at 3, 4, and 6
    • frist sharp cochlear turn around is at 4 tonotopic
    • turbulance and overstimulation of basilar membrane
    • may also see:
    •     problems in acoustic transfer function of outer ear
    •     high freq incr in sound pressure at the eardrum
    •     ear canal resonance around 2500-3
    •     half octave to a full octave above this is about 35-30 hz
  21. if i see a notch at 6, what could this mean
    • firearm because its a hgh freq noise,
    • most impulsive noises mean a notch at 6
    • head shadow causes asymmetry of loss (ie if you use firearm, ear opposite the shot may have more of a loss than the shooting ear.
  22. which industry was the first to enforce regulations
  23. walsh-healey public contracts act in 1936
    contained refs to excessive noise but did not prescribe limits or acknowledge occupational hearing loss prob
  24. osha
    • occupational safety and health act of 1970
    • created within the department of labor
    • charged with establishing safety and health standards for all of general industry
    • created niosh nat inst for occupational safety and health
  25. what does niosh do
    • develops criteria for safe occupational exposures to workplace hazards and recommends standards
    • communicates recommended standards to osha and others
  26. what are the 1972 recommendations for exposure limit
    • 85 dba for 8 hours
    • risk of developing hihl is 8%
    • 3 db exchange rate
  27. what dba does osha use
    • 90 
    • mine safety and health admin uses 90 too
    • 25% excess risk
    •  5 db exchange rate
  28. when did osha amend regulations
    • in 1981
    • they can change enforcement policies but they can not change the law
  29. does osha noise standard amend all industries
    • no
    • only transportation, oil drilling and servicing, agriculture, construction, and mining
  30. what do exposure limits apply to
    • only continuous type noises, not impulsive noises
    • impulsive noises at 140 dba are not to be exceeded for any amount of time
  31. what does osha regulate
    • exposure assessment
    • engineering and admin controls
    • proper use of hearing protectors
    • audiometric eval
    • ed and motivation
    • recordkeeping
    • program audits and eval
  32. what are the elements of a successful hearing conservation program
    • key individual
    • communication
    •     voice concerns
    •     communication line open
    • management support
    •     must be apparent
    •     must be consistent
    •     policy of reinforcement
  33. audiologic management
    • baseline following quiet period of 14 hours for osha, 12 hours for niosh (<75 dba)
    • within 6 months of employment for osha
    • 30 days for niosh
  34. annual hearing test
    • if in working environment above 85dba need to be tested annually
    • at the end of shift
    • if hearing change, retest within 30 days
    • restest at beginning of shift
  35. if the shift still persists then...
    • notify employee in writing within 21 days
    • reinstruct emp on use of hearing protection
    • refit with alternative protection if necessary
    • monitor emps use of hearing protection
    • document
  36. standard threshold shift
    • change of 10 db or more
    • must be present on 2 tests
  37. when should the baseline be revised
    • controversy
    • osha requires
    • decision must be made by professional supervisor not tech
    • revised if change is consistent over two annual tests
  38. what equipment is needed for a baseline
    • vans
    • manual audiometer
    • self recording audiometer
    • industrial sound booth-looks like a large refrig
  39. noise problems
    • ambient noise levels
    • upward spread of masking
    • low freq noise is more prevalent at industrial sites than in professional or commercial buildings
  40. what are the ambient noise levels
    • must be tested prior to audiometric testing
    • can only test down to 25 db for 500 hz
  41. caohc
    • council for accreditation inn occupational hearing conservation
    • influenced government agencies
    • multi disciplinary and non profit
    • requried certification or its equivalent
  42. referral criteria
    employer pays
    • 1. physical problem related to hearing protection
    • 2. suspect test is not valid
  43. what are the required freqs when conducting hearing tests
    5, 1, 2, 3, 4, 6 tabular audiogram used higher incidence of malingering in an industrial pop
  44. when referred, what would be the avg
    • loss>25 dbhl at 5, 1, 2, and 3 difference btw ears
    • >15db avg at 5, 1, 2Hz
    • >30 db avg at 3, 4, 6
    • employer need not pay costs
  45. when would emp need to have annual tests
    • when there is a worsening compared to the baseline audiogram of 
    • >15db avg at 5, 1, 2
    • >20 db avg at 3, ,4, 6
    • employer need not pay
  46. sts
    • standard thres shift
    • pta osha gets worse by 10db or more compared to baseline
  47. what is the standard thres shift for osha
    osha freqs are at 2, 3, 4 and then PTA is the avg of the 3/3
  48. medical referral
    • history of ear pain, drainage, felling of fullness or discomfort, sudden or rapid hearing loss, severe persistent tinnitus
    • evidence of excessive cerumen
    • employer need not pay
  49. when is the baseline revised
    • improvement
    • revise baseline if pta osha improves 5 db or more over two consecutive annual tests
  50. if the hearing is worsening what happens with the baseline then
    • if pta osha worsens by 10db or more on two consecutive annual tests it must be revised
    • baselines are made for each ear
  51. low and high fence
    • low=material impairment
    • high=complete impairment
  52. rate of growth
    difference btw the low and high fences, expressed as %
  53. binaural weighting
    binaural hearing is better than monaural hearing, no consensus
  54. what is the award for
    for disadvantage, loss of wages, or loss of employability that the hearing loss creates
  55. impairment
    a deviation or change for the worse in either aud structure or function, usually outside the range of normal
  56. handicap
    disadvantage imposed by a hearing impairment on a person's communicative performance in activities of daily living
  57. disability
    the determination of a financial award for the loss of function caused by any hearing impairment that results in significant hearing handicap
  58. what does osha say about recreational noise
    40-50 hours/week of on had to be considered a sizeable exposure compared to only 1-4 hours/week of non oc noise
  59. at arms length, if you speak louder than ---- the you are at risk
  60. what does epa regulations not affect
    • it does not affect noise regulations
    • created noise reduction rating (nrr) ear plugs
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hearing conservation
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