Lecture 15 - Hearing Impairment Flashcards
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Why is the cochlear hard to investigate?
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The cochlear is hard to investigate because it is buried in the thickest part of the body and is very close to the facial nerve, the carotid artery, the jugular vein - so is basically the most inaccessible place in the body.
So we work out ways in which we can present sounds to people for them to do tasks with them and make an inference from these results.
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From our knowledge of auditory physiology,
what can cause:
- conductive hearing loss
- sensorineural hearing loss
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See purple writing on page 1 of G doc notes.
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What are the 2 principle tools we use in audiometry?
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See purple writing on page 1 of G doc notes.
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Describe the consequences of the loss of outer hair cells (OHCs) and what studies show this.
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See green writing on page 1-3 of G doc notes.
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Describe the consequences of the loss of inner hair cells (IHCs) and what studies show this.
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See orange writing on page 3 of G doc notes.
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Describe the consequences of endocochlear potential (EP) and what studies show this.
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See blue writing on page 3-4 of G doc notes.
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Describe the consequences of cochlear synaptopathy
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See purple writing on page 4-5 of G doc notes.
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Conclusions:
1) There a multiple potential mechanisms underlying cochlear hearing loss.
2) OHC dysfunction is probably a major source of age-related hearing loss (measured audiologically).
3) OHC dysfunction may be caused by loss of the OHCs or by loss of endocochlear potential.
4) IHC loss is thought to be less common but identification of “dead regions” may be important to avoid amplifying frequencies that can never be properly heard.
5) It remains unclear whether cochlear synaptopathy is a significant problem in humans.
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