Stephen A. Dawkins, MD

1
Occupational Hearing Loss

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

2
Causes of Hearing Loss

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

3
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.

4
Audiogram
5
Decibels and Hertz

• Hertz (Hz)
• Frequency
• Pitch
• Decibels (dB)
• Amplitude
• Loudness

6
Degrees of Hearing Loss
7
Audiogram with Levels of Speech and
Environmental Sounds Superimposed
8
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.

9
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).
• (Continued on the next slide)

10
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).
• (Continued on the next slide)

11
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)

12
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 and training

13
Professional Team

• Professionals typically involved in the hearing
  loss prevention/hearing conservation program at
  the local level
• Audiologist
• Industrial Hygienist
• Safety Officer
• Physician

14
Hearing Protectors

• Must be available if
• Exposed to 85 dB or greater for eight-hour TWA
• Must be worn if
• No baseline audiogram has been established
• Hearing threshold has changed an average of 10 dB
  or more at 2000, 3000, or 4000 hertz in either ear

• Must be worn if
• Duration Sound Level
• (hours per day) (dBA)
• 8 90
• 6 92
• 4 95
• 3 97
• 2 100
• 1.5 102
• 1 105
• 0.5 110
• 0.25 or less 115

15
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

16
Types of Hearing Protectors

• Canal Caps
• Earplugs
• Earmuffs

17
Canal Caps

• Flexible tips
• Do not extend into the ear canal
• Only cover canal opening

18
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

19
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

20
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

21
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
• (Continued on the next slide)

22
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

23
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.