Hearing by cuiliqing


									                                       Course Curriculum for:
                                      Hearing Conservation

I.     Course Prerequisites:
            Hazard Communication Training
            On-site Safety Orientation
II.    Instructor's Qualifications:
            Basic understanding of hearing conservation
            Thorough understanding of OSHA CFR 1910.95
III.   Training Method(s)

               0.5   Classroom hours
               0.5   Demonstration hours

IV.    Course Visual Aids (as needed)

            Noise Protection Devices (ear plugs, ear muffs, etc.)

VI.    Course Contents

       A.    OSHA Action Level

       The purpose of a Hearing Conservation Program (HCP) is to help protect employees from hearing
       loss due to occupational noise exposure. OSHA requires training for all workers who are exposed
       to occupational noise levels at or exceeding an 8-hour time-weighted average of 85 dBA. This is
       known as the OSHA Action Level.

       Discuss all areas where people may be exposed at or above the OSHA Action Level of 85 dBA.

       B.    Hazards of Occupational Noise Exposure

       Noise, or unwanted sound, is one of the most pervasive occupational health problems and is a
       by-product of many industrial processes. Sound consists of pressure changes in a medium (usually
       air) caused by vibration or turbulence. Pressure changes produce waves emanating away from the
       turbulent or vibrating source. High level exposure causes hearing loss and may cause other
       harmful health effects. The extent of damage depends on intensity of noise and duration of
       exposure. Hearing loss can be temporary or permanent.

       C.    How Do We Hear?

       The outer ear collects the sound waves that hit the eardrum and
       cause it to vibrate. These vibrations are sent through the ear
       bones to the cochlea where delicate hair cells vibrate to different
       frequencies. When these hair cells detect the vibration, they send
       a signal to the brain. Loud sounds and intensity destroy the hair
       cells, and they stop functioning - permanently!

       The ear does something else too. The ear has semi-circular canals,
       three tubes laying perpendicular to one another that are filled with fluid
and tiny hair cells. Depending on which way your head is tilted, the fluid moves the hair cells, and
they send a signal to your brain. This is what is responsible for your balance or equilibrium.

D.    Types of Hearing Loss

Hearing loss can be categorized by where or what part of the auditory system is damaged. There
are two basic types of hearing loss:

1.    Conductive Hearing Loss:

Conductive hearing loss occurs when there is damage to the air conduction mechanism and sound
is not conducted efficiently through the outer ear canal to the eardrum and the tiny bones, or
ossicles, of the middle ear. Conductive hearing loss usually involves a reduction in sound level, or
the ability to hear faint sounds. This type of hearing loss can often be medically or surgically

2.    Sensorineural Hearing Loss:

Sensorineural hearing loss occurs when there is damage to the inner ear (cochlea) or to the nerve
pathways from the inner ear (retrocochlear) to the brain. It not only involves a reduction in sound
level, or ability to hear faint sounds, but also affects speech understanding, or ability to hear clearly.
Sensorineural hearing loss cannot be medically or surgically corrected. It is a permanent loss.

E.    Causes of Hearing Loss

Hearing loss can be caused by a one-time exposure to an intense “impulse or impact”
sound, such as an explosion, or by continuous exposure to loud sounds over an
extended period of time. Hearing loss can also occur simply due to aging

Noise - Induced Hearing Loss occurs when we are exposed to noises that are “too loud”, “too
close” or last “too long” and damage the delicate hair cells in our inner ear.

If an ear is repeated exposed to excessive noise, the ear's sensitivity level will decrease as a
measure of protection. This process is referred to as a shift in the Threshold of Hearing, meaning
that only sounds louder than a certain level will be heard. The shift may be temporary, chronic or

Thus a Temporary Threshold Shift (TTS) implies a temporary hearing loss for low levels of sounds.
If the hair cells are not allowed to recover through periods of quiet, they gradually lose their ability to
respond and eventually die causing permanent damage. During short exposure to noise, most
people experience a rise in the auditory threshold which normally disappears in 24 hours, but may
last up to a week. On an audiogram, this type of hearing loss configuration is commonly referred
to as a "noise notch." This can be diagnosed by a “notch” at 4,000 Hz.

Permanent hearing loss, also known as Permanent Threshold Shift (PTS), progresses constantly
as noise exposure continues month after month and year after year. Major damage occurs in the
first 5 to 10 years of work in a noisy environment. The hearing impairment is noticeable only when
it is substantial enough to interfere with routine activities. At this stage, a permanent and irreversible
hearing damage has occurred to the hair cells in the cochlea. Noise-induced hearing damage
cannot be cured by medical treatment and worsens as noise exposure continues. Diagnosis is
similar to TTS but with a deepening and widening “notch” at 4000 Hz in an audiogram.
                                           Record of Training for:
                                           Hearing Conservation

I.     Date of Training: _______/______/______

II.    Method of Training:

                 •                        Hours of classroom instruction
                 •                        Hours of practical or hands on training

III.   Course Contents:

         A.    OSHA Action Level
         B.    Hazards of Occupational Noise Exposure
         C.    How Do We Hear
         D.    Types of Hearing Loss
         E.    Causes of Hearing Loss
         F.    Ear Anatomy
         G.    What is Sound
         H.    Hearing Protection
                   Types of Hearing Protection
                   Advantages and Disadvantages
                   Proper Use of Hearing Protection
         I.    Audiometric Testing
         J.    Curriculum Quiz

IV.    Visual Aids and Handout Materials:

             Noise Protection Devices (ear plugs, ear muffs, etc.)

V.     Student's Acknowledgment:
       I hereby acknowledge that I have completed the training course outlined above and understand
       the material presented to me.

                  Employee’s Signature                                Employee’s Name Printed

VI.    Instructor's Certification:
       Through class participation and quiz completion, the above named student has successfully
       demonstrated the knowledge and abilities as defined in the course objectives.

                  Instructor’s Signature                              Instructor’s Name Printed
                                   Curriculum Quiz for :
                                 Hearing Conservation

                                                       Written Test Score:
                                                       Passing Score:      =     80%


1.        True     False   Hearing loss can be permanent.

2.        True     False   Hearing protectors work properly only when used as instructed by the
3.        True     False   Cotton balls in your ears will provide adequate protection from high noise levels.

4.        True     False   Noise levels can be measured accurately in the workplace.

5.   Which of the following can be caused by exposure to high levels of noise?
     a.      Damage to the inner parts of the ear
     b.      Loss of effectiveness due to increased stress
     c.      Loss of all or part of your hearing
     d.      Missing safety warnings or instructions
     e.      All of the above

6.   Noise is:
     a.      Unwanted sound,
     b.      One of the most pervasive occupational health problems,
     c.      A by-product of many industrial processes,
     d.      None of the above
     e.      All of the above

7.   When exposure to high levels of noise without proper protection, the ear's sensitivity level will
     decrease. This process is referred to as:
     a.      Going deaf
     b.      A shift in the Threshold of Hearing
     c.      Audiometric desensitivity
     d.      A miracle

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