Chapter 2 Flashcards
Components of a hearing aid
Microphone
Amplifier
Receiver
Batteries
Components of HA microphone
Transduces acoustic energy into electric energy
Directional - picks up sound from the front - greatly improves SNR, increasing word understanding
Omnidirectional - picks up sound from all directions equally
Amplifier (digital processor ) of HA
Converts electric signal from microphone to digital (analog-to-digital)
Allows different programs for: noise, music, telephone, etc
Uses algorithms to improve speech perception
Receiver - HA component
Converts electric signal to acoustic signal
Larger the receiver the greater output
Designed to be shock resistant, but can be damaged by cerumen, oils, moisture
Behind the ear BTE
Microphone at top of ear
Sound transmitted from receiver through earhook to tubing and then ear old
Preferred style for pediatrics due to changing ear size and shape
Excellent for adults with dexterity issues
Less susceptible to damage
Easy access to control buttons
All electronics are in case
What is head shadow?
Reduction of sound intensity b/c obstruction of head
Creates changes in frequency and phase of sound picked up by 2 ears
Receiver in the canal RIC
Blend of BET and ITE
Great for high frequency gain without feedback
Little or no occlusion
Cosmetically appealing
Extended Wear Hearing Aids (Phonak Lyric)
Placed deep in the ear canal
Remain until battery dies
1 year contract
Reduces occlusion
Improves localization
Reduces effect of wind
CONS: fit up to to 60 dB loss at low frequency gain and 30-90 dB at high frequency
Contraindication scuba and sky diving, diabetes, those who easily bruise
In the ear ITE, ITC, CIC
Custom molded to individual
Named by amount of the concha bowl that is filled (ITE-fill entire concha, ITC-fit in the canal, CIC-barely visible
Size limits the power of the HA
More natural microphone placement
Occlusion effect with high frequency HL is an issue
Completely in the canal CIC
Cosmetic advantage
Receiver is closer to the TM, naturally boosting high frequency sounds
More susceptible to damage from cerumen, oil, moisture…
Earmold
Funnels sound from the HA into ear
Made of different materials - hard plastic, vinyl, silicone
Changes in thickness of tube impacts gain and frequency.
Thicker tube can aid in prevents feedback
Ear hook can be half moon or quarter moon
Vent of earmold
Reduces over amplification of low frequency sounds
Relieves occlusion effect
Keeps ear canal cooler and drier
Larger vents are more susceptible to feedback
Sizes: full shell, 1/2 shell, skeleton
Advantages to acrylic
Durable
Easily modified in office
Appropriate for mild to severe loss
Easily inserted
Most appropriate for adults
Advantages to silicone
Softer than acrylic
May expand to reduce slit leaks
Appropriate for mild to severe loss Easily loss
CANNOT modify in office
Advantages to soft silicone
Flexes to accommodate TMJ movement
Better seal for profound loss
Good choice for sports and kids
Perform listening check
-look at hearing aid for physical problems
Put battery in and turn on
Use hearing aid stethoscope to listen
Refer to audiologist if any problems
Factors to consider for HA candidate
Degree and type of hearing loss
Communication disability
Motivation
Degree of HL factors for HA
Hearing thresholds greater than 25 dB between 250-4000 Hz
Children - if fluctuating hearing loss wait. If constant and greater than 15 dB give hearing aid
HA can be appropriate for ANY type of loss. Always refer to ENT to rule out medical. There are times can’t medically treat CHL so HA best option
Hearing Aid Candidacy - communication disability
What is the impairment on communication
Self-report questionnaires
Significant other questionnaires
Hearing Aid Candidacy - Motivation
Cost
Cosmetics
Health
Attitude
Denial
Hearing Aid Fitting Protocol
Selection - based on gain needed for HL, dexterity of patient, cosmetic concerns, age, additional programs, directional microphones, etc.
Quality control - testing to be sure the HA is up to spec
Fitting - prescriptive fitting formulas, Real Ear Measurement
HA Fitting Steps
Audiologist chooses appropriate fitting formula: NAL or DSL
Real Ear Measurement
Counseling
What is NAL
National Acoustic Laboratory
Most popular for adults
What is DSL
Desired Sensation Level
Most popular formul for children
Have more higher frequency sounds