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
Real Ear measurement
Must be utilized every time get Ha
Fine tune HA settings in the softwares based on RE response and patient feedback
Assesses ear canal, etc
Has tremendous effect on volume needed
RE gives targets and settings can be adjusted
Uses audiogram thresholds and does calculations
What is done for counseling?
Hearing aid orientation (care and use)
Realistic expectations
-does not cure hearing loss
-maximizes residual hearing
Hearing Aid Orientation
HIO-BASICS
See handout
Validation/Outcome Measures
Electroacoustic outcome measure
-real ear measurements
-test box (verify meeting targets)
Audiologic measures
-aided and unaided word recognition
——testing in quiet and noise
Self-report measurements
-patients use
-perception of benefit
-satisfaction
Pediatric hearing aid fitting - testing
Team approach
Early identification
Battery of tests needed to diagnose, monitor and re-evaluation***
-OAE
-ABR and /or ASSR
-Behavioral
Goal is to try to obtain behavioral thresholds in both ears and test speech perception
Pediatric HA fitting
RE measurements must be done in ALL because size and shape of ear canal changes often
DSL is preferred fitting formula because focuses on high frequency sounds
Earmold fit needs to be closely monitored
-impressions every 3 months in early years
Have to do in test box for infants and toddlers that won’t hold still or real ear to coupler difference (comparing size and shape of patients ear to coupler)
HA retention - one of the biggest challenges is keeping them in place
-sweat bands
-type tape
Typical schedule for HA adaptation - pediatric
Week 1: in quiet, controlled environment, 15-30 minutes during fun activity. Parent removes the HA.
Week 2: gradually increase HA time
Week 3: hearing aids should be in use during all waking hours routines…except activities with water
Pediatric follow up
HA check every 3 months during first 2 years
-earmold checks
-behavioral audiometric evaluations
-electroacoustic evaluation (RE or test box)
Parent questionnaires to assess benefit - IT-MAIS or ELF
Team approach
Options for unilateral profound hearing loss
CROS
Bone conduction hearing aid
Bone anchored device (BAHA)
CROS - Contralateral routing of the signal
-UNILATERAL HEARING LOSS
-microphone placed in poorer ear, sound is transmitted to good ear
-PROFOUND HEARING LOSS in one ear, normal hearing in one ear
Why not hearing aid? Normal ear doesn’t need aid. Profound loss cannot process speech. Need hearing from both sides for hearing in noise and locatlization
Bone conduction hearing aid
Cochlea and beyond have to be in tact!
Non-invasive
Recommended for:
-chronic middle ear infections
-atresia
-there is a microphone and receiver. Signal creates vibrations in response to sound and the input is transmitted to the good ear via bone conduction
-UNILATERAL HEARING LOSS
Bone anchored devices BAHA
Surgically implanted hearing device
ENT determines candidacy and conducts surgery
Most often prescribed in single-sided deafness
Not a candidate until age 5
****HAVE CLEAR EXAMPLES FOR BAHA, CROS, AND BONE CONDUCTION HEARING AIDS
BC has 0 dB intra oral attenuation - crosses over to other ear
Candidates for middle ear implantable hearing aids
Moderate to severe sensorineural hearing loss
Cannot tolerate foreign bodies in ear canal
Require a free canal for personal or professional reasons (doctor, etc)
Rely on good perception of high frequency sounds
Middle ear implantable hearing aids
Very expensive, insurance doesn’t pay for it
Good for 4-9 years and then has to be replaced
Externally worn microphone, Processor implanted in mastoid, driver is attached to stapes
Benefits of middle ear implant
Cosmetic
Swimming
Feedback issues
Free ear canal
No HA discomfort
Cochlear implant
DESIGNED FOR PATIENTS WITH SEVERE - PROFOUND SENSORINEURLA HEARING LOSS THAT DO NOT BENEFT FROM TRADITIONAL HEARING AIDS
Electrode array surgically implanted in cochlea
Implant bypasses damaged cochlea and stimulates auditory nerve directly
Hearing Assistive Technolgy (HATS/ALD)
Used in combination with HA and CI.
Device needed depends on age, lifestyle, listening demands, etc.
Designed to improve the ability to hear in noise or from distance
-FM/RM sound system
-infrared systems
-audio loop system
Can be: telephone listening device, television listening device, alerting device
Sound field system
Technology for classroom
Voice is transmitted to speaker - boosts high frequency sounds
Good for ELL (English language learners), slight to mild hearing loss, kids with artic problems
Sound quality of teacher is better.
