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CD 443 Final Study Guide – Questions With Solutions
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CD 443 Final Study Guide – Questions With Solutions
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CD 443 Final Study Guide – Questions With SolutionsHearing aids Right Ans - amplify the signal to
compensate for sensitivity loss.
• Rely on remaining inner hair cells to transduce the signal and stimulate
auditory nerve.
Conductive hearing loss Right Ans - Most conductive losses are medically
or surgically treatable
- Examples: Cerumen impaction, acute otitis media, chronic otitis media,
perforated eardrum
- People with permanent CHL do very well with hearing aids
• Some people may use a bone conduction aid
Sensorineural hearing loss Right Ans - - Most sensorineural hearing losses
are sensory, not neural
• Problem in cochlea
• Frequently, the outer hair cells
- Outer hair cells are extremely vulnerable to insult
- Degree of hearing loss tends to be related to the amount of hair cell damage
• The greater the degree of hearing loss the more likely outer and inner hair
cells involved
Most with sensorineural losses benefit from hearing aids (depending on
degree) Right Ans - - Amplifying the signal overcomes the sensitivity loss
due to hair cell damage
• Caveat: Hearing aids do not provide normal hearing
- Amplifying sound not making a person's thresholds better
- Making sound more audible
Hearing aids = miniature amplifiers Right Ans - Capture incoming sound,
increase its intensity, and deliver it to the ear
Modern Hearing Aids Right Ans - - Less focus on miniaturization, more
focus on improving performance
- Holy grail of hearing aids: Improve speech perception in noise
• Changes in signal processing technology • Changes in microphone
technology
, Open-fit technology Right Ans - New in 2005
- Key ingredients
• Fitted to ear with narrow tube
• Digital feedback cancellation
- Excellent for high-frequency hearing losses
- Have led to large increase in BTE sales
• Jump from 25% to approx. 50% in 2007
How hearing aids work Right Ans - 1. Sound is picked up by the
microphone
- Converts acoustic signal to an electrical signal
2. This electrical signal is then amplified and/or processed in some way
3. The receiver converts the electrical signal back to an acoustic signal
- In a BTE, sound is delivered to the ear canal by the earmold
Three main types of processors or circuits Right Ans - Analog, digital, and
hybrid or "digitally programmed"
Analog Right Ans - Sound is processed as a continuous electrical signal
(generated by the microphone)
- Signal is modified by electronic components
- Hearing aid characteristics are adjusted by screw settings
Digital Right Ans - - Electrical signal from mic is converted into 1's and 0's
- Computer chips carry out the various signal modifications
- Characteristics are programmed using specialized software
- Can store multiple sets of characteristics
- First true digital hearing aids debuted in 1998
Hybrid or "digitally programmable" Right Ans - - Sound remains in analog
form
- Electronic circuits modify the signal
- However, hearing aid settings are controlled using computer software and
stored in the hearing aid digitally
- Can have multiple settings stored
- Debuted around 1990
hearing aid features Right Ans - Automatic volume control
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