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					Occupational Hearing Loss

    Dr. Stephen A. Dawkins
Caduceus Occupational Medicine
         April 7, 2005

           Stephen A. Dawkins, MD
        Caduceus Occupational Medicine
       Causes of Hearing Loss

•   Noise Exposure
•   Congenital Disorders
•   Genetic Causes
•   Infections
•   Ototoxic Drugs
•   Head Trauma

                 Stephen A. Dawkins, MD
              Caduceus Occupational Medicine
         Types of Hearing Loss
• Conductive Hearing Loss
  – Involvement of Outer and/or Middle Ear
     • Most often this is medically or surgically treatable.
• Sensorineural Hearing Loss
  – Inner Ear
     • Most often is permanent and not medically/surgically
       treatable.
     • Treatment usually involves aural rehabilitation which
       includes the fitting of amplification devices.


                        Stephen A. Dawkins, MD
                     Caduceus Occupational Medicine
Audiogram




   Stephen A. Dawkins, MD
Caduceus Occupational Medicine
         Decibels and Hertz
• Hertz (Hz)
  – Frequency
  – Pitch
• Decibels (dB)
  – Amplitude
  – Loudness


                   Stephen A. Dawkins, MD
                Caduceus Occupational Medicine
Degrees of Hearing Loss
                                        0

                                       10                  NORMA L
                                                           HE AR IN G
                                       20
 HEARING LEVEL IN d B (A NSI, 1996)




                                       30                    MILD
                                                        HE AR IN G LOSS
                                       40
                                                         MOD ERA TE
                                       50               HE AR IN G LOSS

                                       60                     E
                                                     MODE RA T LY --S EVE RE
                                                        HEA RIN G LOSS
                                       70

                                       80                   SEV ER E
                                                        HE AR IN G LOSS

                                       90
                                                          P ROFOU ND
                                      100               HE AR IN G LOSS


                                            250      500     1000     2000     4000   8000
                                                      FR EQU Dawkins, MD
                                                  Stephen A. EN CY IN Hz
                                             Caduceus Occupational Medicine
Audiogram with Levels of Speech and Environmental Sounds Superimposed

                                                                   FREQUENCY IN Hz
                                                   250            500   1000   2000        4000       8000


                                               0
          HEARING LEVEL IN dB (ANSI, 1996)



                                              10

                                              20                                               f st
                                                                                  p               h
                                                     zv                               h    k
                                              30                                       g
                                                                              c
                                              40   j mdb ia                   h s
                                                     n n   o r                  h
                                              50       e
                                                       g l
                                                       u
                                              60

                                              70

                                              80                             BU
                                                                             D
                                              90
                                                                  MOUNTAIN
                                             100                    EXPR
                                                                  HOME ES
                                                                    S

                                             110
                                                         VIR GI
                                                         N

                                                            Stephen A. Dawkins, MD
                                                         Caduceus Occupational Medicine
           Definition:
     Standard Threshold Shift
• A standard threshold shift is a
  decrease in hearing threshold
  relative to the baseline audiogram of
  an average of 10 dB or more at 2000,
  3000, and 4000 Hz in either ear.



                Stephen A. Dawkins, MD
             Caduceus Occupational Medicine
   Standard Threshold Shift (1)

• What happens when a decrease in
hearing (Standard Threshold Shift or
STS) is detected in the annual
audiometric evaluation:
– Employee is informed of STS in writing
  within 21 days (29 CFR 1910.95 g 8 i).
– Employee is retested within 30 days to
  verify STS (29 CFR 1910.95 g 7 ii).

                  Stephen A. Dawkins, MD (Continued on the next slide)
               Caduceus Occupational Medicine
    Standard Threshold Shift (2)

• If STS verified and is work related then:
  – If not using hearing protection employee shall be
    fitted and trained in the use and care of PPE (29
    CFR 1910.95 g 8 ii A).
  – If employee is using hearing protection the
    employee shall be refitted and retrained (29 CFR
    1910.95 g 8 ii B).
  – The employee shall be referred for a clinical
    audiological or otological evaluation, as
    appropriate (29 CFR 1910.95 g 8 ii C).

                     Stephen A. Dawkins, MD (Continued on the next slide)
                  Caduceus Occupational Medicine
  Standard Threshold Shift (3)

• Employee is informed of the need for
  an otological examination if a
  medical pathology of the ear that is
  unrelated to the use of hearing
  protectors is suspected.
        (29 CFR 1910.95 g 8 ii D)


                Stephen A. Dawkins, MD
             Caduceus Occupational Medicine
       Components of a Hearing
        Conservation Program
• Assessment and monitoring of workplace
  noise and noise exposure

• Control of workplace noise and noise
  exposure

• Measurement of hearing

• Employee education A. Dawkins, MD
                Stephen
                        and training
                Caduceus Occupational Medicine
         Professional Team
• Professionals typically involved in
  the hearing loss prevention/hearing
  conservation program at the local
  level:
  – Audiologist
  – Industrial Hygienist
  – Safety Officer
  – Physician
                  Stephen A. Dawkins, MD
               Caduceus Occupational Medicine
               Hearing Protectors
• Must be available if:                • Must be worn if:
     • Exposed to 85 dB or
                                              Duration     Sound
       greater for eight-hour
       TWA
                                              Level
                                           (hours per day)    (dBA)
• Must be worn if:                             8              90
     • No baseline audiogram                   6              92
       has been established
                                               4              95
     • Hearing threshold has
                                               3              97
       changed an average of
       10 dB or more at 2000,                  2              100
       3000, or 4000 hertz in                  1.5            102
       either ear                              1              105
                                               0.5            110
                                               0.25 or less
                          Stephen A. Dawkins, MD              115
                        Caduceus Occupational Medicine
      General Considerations
• Proper initial fit required
• Must be used correctly
• Must receive training in the use and care
  of hearing protectors provided
• Must be allowed to select hearing
  protectors from a variety of suitable
  hearing protectors provided by employer
• Must be replaced as necessary

                  Stephen A. Dawkins, MD
               Caduceus Occupational Medicine
   Types of Hearing Protectors
• Canal Caps

• Earplugs

• Earmuffs




                  Stephen A. Dawkins, MD
               Caduceus Occupational Medicine
              Canal Caps
• Flexible tips

• Do not extend into the ear canal

• Only cover canal opening



                 Stephen A. Dawkins, MD
              Caduceus Occupational Medicine
                Earplugs
• Lightweight
• Comfortable for long periods of time
• Made of soft fibers or foam (self-
  forming)
• Disposable or reusable
• Preformed, pre-molded, or custom
  molded

                 Stephen A. Dawkins, MD
              Caduceus Occupational Medicine
               Earmuffs

• Easily put on or removed
• Require entire ear to fit inside cup
  (seat)
• May interfere with glasses or goggles
• Can be designed for use with hard
  hats


                Stephen A. Dawkins, MD
             Caduceus Occupational Medicine
            Hearing Safety
• If you have to shout to talk to someone
  within 2 or 3 feet - Wear hearing protection
• Off-the-job activities (woodworking,
  shooting, etc.) can hurt your hearing -
  Hearing protection is recommended
• Never remove hearing protection in high
  noise areas
• Do NOT share hearing protection with
  others
                  Stephen A. Dawkins, MD
               Caduceus Occupational Medicine
  Test Yourself to Recognize Hearing
               Loss (1)
The following questions will help you determine if you need to
have your hearing evaluated by a medical professional:
 Do you have a problem hearing over the telephone?
  [Yes] [No]
 Do you have trouble following the conversation when two or
  more people are talking at the same time? [Yes] [No]
 Do people complain that you turn the TV volume up too high?
  [Yes] [No]
 Do you have to strain to understand conversation?
  [Yes] [No]
 Do you have trouble hearing in a noisy background?
  [Yes] [No]
                          Stephen A. Dawkins, MD (Continued on the next slide)
                       Caduceus Occupational Medicine
Test Yourself to Recognize Hearing
             Loss (2)
 Do you find yourself asking people to repeat themselves?
  [Yes] [No]
 Do many people you talk to seem to mumble (or not speak
  clearly)?
  [Yes] [No]
 Do you misunderstand what others are saying and respond
  inappropriately? [Yes] [No]
 Do you have trouble understanding the speech of women
  and children? [Yes] [No]
 Do people get annoyed because you misunderstand what
  they say? [Yes] [No]

                       Stephen A. Dawkins, MD
                    Caduceus Occupational Medicine
  Test Yourself to Recognize Hearing
               Loss (3)
• If you have answered "yes" to three or more of
  these questions, it is suggested that you consult an
  otolaryngologist (an ear, nose, and throat specialist)
  or an audiologist for a hearing evaluation.
• The material on Slides 14-16 is for general
  information only and is not intended for diagnostic
  or treatment purposes. A doctor or some other
  health care professional must be consulted for
  diagnostic information and advice regarding
  treatment.

                      Stephen A. Dawkins, MD
                   Caduceus Occupational Medicine

				
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