Lecture 7 Flashcards
When to use a hearing aid
The more loss, the greater benefit from a hearing aid Greater degree of loss reduced benefit Most often used for sensorineural Motivation Lifestyle
Bilateral hearing aids
Better speech recognition in noise
Better localization ability
Less power required from each hearing aid
Almost always better, but obviously more expensive
Hearing aids can
Speech understanding in quiet
Speech understanding in noise
Loud sounds tolerable
Comfortable fit
Hearing aids can’t
Give perfect hearing Bionic hearing Get rid of annoying sounds Cure hearing loss Work instantly
How a hearing aid works
Microphone changes sound to electricity Amplifier boosts electrical signal Receiver changes electricity back to sound Battery for power Controls to adjust hearing aid response
Behind the ear (BTE)
Most powerful, durable (don’t have to clean as often), lowest repair rate, easiest to operate, largest controls but may be difficult to position behind the ear
In the ear (ITE)
Custom made
Easiest to insert for wearers with dexterity problems
Suitable for all BUT severe hearing loss
Limited by power
In the canal (ITC)
Smaller batteries and volume wheel, may be difficult for wearers with dexterity or vision problems
Suitable for mild to moderate hearing loss
Completely in the canal (CIC)
Smallest aid
Highest repair rate
Not suitable for: dexterity/vision problems, usually shaped or small ear canals, severe loss
Open fit
Has BTE processor, thin tube, and open mold
Can be fit same day in office
May be prone to feedback
Not suitable for greater than moderate hearing loss
Bone anchored hearing system (BAHS)
Transmits sound the same way as the bone conduction vibrator used for audiometry
Surgically implanted
Main uses: for permanent conductive loss, atresia, profound unilateral loss
Goal when fitting hearing aids
Make soft sounds audible
Make average speech maximally audible
Make sure loud sounds are comfortable
Gain
How much the hearing aid has increased the sound level
Frequency response
Amount of gain as a function of frequency, for example most hearing losses are worse at high frequencies and require a hearing aid with more gain in the high frequencies
Linear hearing aids
Provide same gain for every input level until they reach maximum limit
Compression hearing aids
Automatically adjust volume, more gain for soft input, less gain for loud input
Can be adaptive
Detectors in the hearing aid monitor the sound level
Different amounts of compression at different frequencies
Directional microphone
2 microphones, one forward and one backward facing
- in directional mode, amplifies sound from the front, reduces sound from the rear
Improve speech understanding in noise by 30%
Feedback management
Get ears cleaned out Make sure earmold fits tightly in the ear Reduce high frequency gain Turn the volume down Feedback cancellation
Feedback cancellation
Hearing aid feature that can detect feedback and then produce a signal that is opposite in amplitude and phase and in doing, eliminate the signal
Hearing aid trouble shooting
Clean?
Broken?
Battery?
Sound?
Cochlear implant
Assistive technology for people with severe to profound hearing loss who do not benefit from conventional amplification
External: speech processor and transmitter coil
Internal: receiver-stimulator, electrode array
CI candidacy adults
Moderate to severe/profound hearing loss
Limited benefit from amplification
No medical contraindications
Realistic expectations
CI candidacy children
Bilateral severe to profound
Limited benefit from hearing aids for 3-6 mos
At least 12 months old
Inner ear can accommodate the implant
No medical contraindications
Family with good motivation and realistic expectations
Enrolment in appropriate education program
