Hearing and Hearing Loss - PowerPoint by liwenting

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									Hearing, Hearing Loss and Hearing
            Research
 Virginia Lion’s Hearing Foundation
Our ears…
…help us with sounds…
…from very quiet sounds…
…to very loud sounds…
…beautiful sounds…
…and not so beautiful sounds…
…even sounds we’d just rather not hear…
 Basic Facts About Hearing Loss
• 36 million Americans                   • What Causes Hearing
  have hearing loss                        Loss?
   – More than half of these                – Exposure to excessive
     people are younger                       loud noise
     than age 65                            – Ear infections, trauma,
   – The 3rd most common                      disease
     health problem in the                  – Certain illness and/or
     United States                            medications
   – Negative impact on                     – Genetic factors
     speech understanding                   – Hearing loss due to
     and overall quality of                   natural aging process
     life
               *American Academy of Audiology: www.audiology.org
            Hearing Loss in Children
Congenital Hearing Loss
• About 3-6 of every 1,000 children in the U.S.
  are born with hearing loss
   – More may lose their hearing later in
     childhood
• More than 95% of newborns who are born
  deaf have parents with normal hearing

 *National Institute on Deafness & Other Communication Disorders: http://www.nidcd.nih.gov/health/hearing/
            Hearing Loss in Children
Importance of Universal Newborn Hearing
  Screening
• Hearing loss is invisible; it cannot be seen by
  physical examination
• Most newborns with hearing loss have no
  obvious signs or symptoms
• Early intervention is crucial for developing
  age-appropriate communication skills


 *National Institute on Deafness & Other Communication Disorders: http://www.nidcd.nih.gov/health/hearing/
The Ear
The Ear
The Ear
The Ear
The Ear
      How Does the Ear Work?
1. Sound waves from the
   environment enter via
   the outer ear and
   continue through the
   ear canal to the
   eardrum.

2. These waves cause the
   eardrum to vibrate,
   which sets the three
   tiny bones in the
   middle ear into           *University of Maryland Medical Center:
                           www.umm.edu/otolaryngology/ear_works.htm
   motion.
      How Does the Ear Work?
3. The motion of the
   bones causes the
   fluid in the inner ear
   or cochlea to move.

4. Movement of inner
   ear fluid causes the
   hair cells in the
   cochlea to bend and
   change the
   movement into
   electrical pluses.         *University of Maryland Medical Center:
                            www.umm.edu/otolaryngology/ear_works.htm
      How Does the Ear Work?
5. These electrical
   impulses are
   transmitted to the
   hearing (auditory)
   nerve and up to the
   brain, where they are
   interpreted as sound.




                             *University of Maryland Medical Center:
                           www.umm.edu/otolaryngology/ear_works.htm
        Typical Signs of Hearing Loss
   • Do you have a problem hearing over the telephone?
   • Do you have trouble following the conversation
     when two or more people are talking at the same
     time?
   • Do people complain that you turn the TV volume up
     too high?
   • Do you have to strain to understand conversation?
   • Do you have trouble hearing in a noisy background?

*National Institute on Deafness & Other Communication Disorders: http://www.nidcd.nih.gov/health/hearing/10ways.asp
        Typical Signs of Hearing Loss
   • Do you find yourself asking people to repeat
     themselves?
   • Do many people you talk to seem to mumble (or
     not speak clearly)?
   • Do you misunderstand what others are saying and
     respond inappropriately?
   • Do you have trouble understanding the speech of
     women and children?
   • Do people get annoyed because you misunderstand
     what they say?
*National Institute on Deafness & Other Communication Disorders: http://www.nidcd.nih.gov/health/hearing/10ways.asp
Noise Induced Hearing Loss (NIHL)
• Of the 36 million Americans with hearing
  loss, 1 in 3 developed their hearing loss as a
  result of noise exposure
• Caused by damage to hair cells that are
  found in the cochlea.
    – Once damaged, human hair cells cannot
      grow back. This is what causes permanent
      hearing loss.

• Harmful sounds are:
    – Too loud and last too long
         • i.e. Use of heavy equipment and/or power
           tools daily
    – Very loud and sudden
         • i.e. Being near an explosion or other impulse
           sound

          *American Academy of Audiology: http://www.howsyourhearing.org/prevention.html
 Hearing Conservation & Preservation
• NIHL is 100% preventable with proper education!
• How do you protect and preserve your hearing?
     – Know which noises can cause damage
           • OSHA recognizes sounds louder than 85 dBHL as ‘harmful’ over time
     – Wear hearing protective devices, such as earplugs, when involved in a
       loud activity
           • Available at hardware and sporting goods stores
           • Custom products available from an audiologist
     – Educate family & friends
     – If hearing loss is suspected, contact an audiologist for a full evaluation
• Check out the WISE EARS!® Campaign for more information
     – http://www.nidcd.nih.gov/health/wise/

*National Institute on Deafness & Other Communication Disorders: http://www.nidcd.nih.gov/health/hearing/noise.asp
Hearing Aids
                     Hearing Aids




• Fact:
   – Only 1 out of 5 people who could benefit from a hearing aid
     actually wears one.
   – In most instances, two hearing aids are better than one.
   – A hearing aid will not restore normal hearing; however, it
     should improve overall understanding of speech in the
     presence of hearing loss.
                     Hearing Aids
• Hearing aids come in many
  shapes, sizes, and colors. Each
  type of hearing aid is different
  and is appropriate for different
  types and configuration of
  hearing loss.

• Work with a licensed
  audiologist to select a hearing
  aid that best suits your own
  needs and personal lifestyle.
Hearing Aids
Hearing Aids
                       Other Options
In more severe hearing losses with
more hair cell damage, a hearing aid
may not be beneficial.

What other options are available?
• Cochlear Implant
   – A surgically implanted electronic
      device that provides a sense of sound
      to a person who is profoundly deaf or
      severely hard of hearing
   – Bypasses damaged structures in the
      inner ear and directly stimulates
      auditory nerve
   – Candidacy is regulated by the FDA
                 Useful Resources
• American Academy of Audiology
   – http://www.howsyourhearing.org/whatisanaudiologist.html
• American Speech Language & Hearing Association
   – http://www.asha.org/public/hearing/
• Early Hearing Detection and Intervention (EHDI)
   – http://www.cdc.gov/ncbddd/ehdi/
• National Institute for Deafness and Other (NIDCD)
  Communication Disorders
   – http://www.nidcd.nih.gov/health/hearing/
• National Institute for Occupational Safety and Health
  (NIOSH)
   – http://www.cdc.gov/niosh/topics/noise/
• Occupational Safety & Health Administration (OSHA)
   – http://www.osha.gov/SLTC/noisehearingconservation/
Hearing Research at UVA
  Supported by VLHF
Development of mouse auditory
         hair cells




          Gwenaelle S.G. Geleoc, PhD
     Associate Professor, University of Virginia
                    Development of mouse auditory hair cells.
                                                                                       Scanning electron micrographs
                                                                                       show sensory hair bundles from
                                                                                       outer hair cells at P0, P3 and P6
                                                                                       across the Organ of Corti.
                                                                                       Developmental changes in the
                                                                                       hair bundles length and shape
                                                                                       are observed during the first
                                                                                       postnatal week.




                 First             Basal hair cells                                                           Onset
               Hair cells       are mechanosensitive                                                        of hearing


10   11   12   13    14   15   16   17   18   19   00   01   02   03    04   05   06    07   08   09   10   11   12   13   14

Embryonic
stages (in days)
                                               Birth
                           Small                                       All cochlear hair cells
                    hair bundles appear                                   take up FM1-43
                      (Anniko 1983)
                            FM1-43 uptake in P4 cochlea
        Base                                                                                     Apex




          B                            BQ                            AQ                           A
FM1-43 , which permeates transducer channels, is used to determine when hair cells become functional.
This illustration shows four sections of the organ of Corti from its base (B) to apex (A). The upper panel
shows DIC micrographs where outer hair cell hair bundles can be seen. At P4, strong uptake is seen at the
base and very little at the apex. The apex is fully mature by P6.
      Recording from mouse auditory hair cells




                                   B                             C




                                                       50pA


                                       0      40       80     -0.4   0.0       0.4       0.8
                                           Time (ms)                 Displacement (m)

Transduction current can be recorded from mouse hair cells using the patch clamp technique
while displacing the hair bundle with a stiff probe.
                   The Holt-Geleoc Lab




Jeffrey R. Holt, Ph.D.
Gwenaelle Géléoc, Ph.D.
Bradley W. Kesser, M.D.
Andrea Lelli, Ph.D. (Postdoc)
Yukako Asai, Ph.D. (Postdoc)
Charlie Askew (Graduate Student)
Michaela Levin (Graduate Student)
Ye-Hyun Kim (Graduate Student)
Geoff Horwitz (Graduate Student)
Laura Digilio (Lab Manager)
Mark Rollag, Ph.D. (Visiting Scholar)
When we know more about how
 the ear works and develops,
we may be able to cure
    hearing loss

								
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