Final Flashcards
How to qualify for HAs
- “significant” HL (mostly mild HL or worse; CHL or SNHL)
- medical clearance for CHILDREN not adults
- data needed: PTA/B, speech reception threshold (softest level they can repeat words), speech recognition in quite & noise
Dynamic range
- usable range; difference b/t dB(PTA) & threshold
- larger range in people w/out HL
Recommended time frame for children getting HAs
screening by 1 month, HL identified by 3 months, intervention by 6 months
stages of change
process where people vary their readiness to change (get HAs)
1. pre-contemplation (denial)
2. contemplation
3. preparation
4. action (Auds work here)
5. maintenance
How do HAs work?
- mic (acoustic signal) is transduced into electrical signal
- amplifier increases strength/loudness of signal
- receiver/speaker (electrical signal) is transduced back to acoustic signal
HA Microphone
- transducer
- converts acoustic to electrical signal
- sound waves move diaphragm & coil back & forth
- coil is wrapped at magnet (creating a current)
- electrical signal is sent to amp
HA Amplifier
- electronic device that increases amplitude of voltage (current of signal)
- generates a larger current electrical signal sent to receiver/speaker
HA Receiver/Speaker
- converts electrical signal (from amp) to acoustic signal
- considered a small loudspeaker
HA Batteries
- +/- proper insertion
- 3-22 day battery life
- 13, 312, & 10A are most common
Most common HA
BTE - mild to severe
Common BTEs
Open fit - clear tubing
RITE & RIC - wire in tubing
- mild to moderate (mostly SNHL)
Which type of HA has a longer adjustment period
Digital (DSP)
Where does the mic & receiver go for HAs (CROS)
mic - bad ear
receiver - good ear
Standard BTE
- mild to severe
- good dexterity
- larger controls
- 2 components: unit + HA
- less feedback
ITE/ITC
- mild to moderate
- okay dexterity
- 1 unit
- enhanced amp of high frequencies
- wax can block speaker
CIC
- mild to moderate
- cosmetically appealing
- reduction of occlusion effect (booming sound) & feedback
- less gain needed
- elimination of wind sound
Circuitry
- guts of HA
- Analog vs. Digital
- depends on severity of HL
Digital Signal Processing (DSP)
- compression features allow soft sounds to be amplified more than loud sounds
- noise reduction circuits work better than analog
- self adjusting
Analog Signal Processing (ASP)
- make sound waves louder
- amplifies all sound (speech & noise)
- most are still programmable
- less expensive
Binaural vs Monaural
- 60% of people with HL are fit with 2 HAs
- localization improved (eliminates head shadow effect)
- loudness summation adds signal received to both (3dB benefit in both ears)
- ears working together to suppress background noise
- BUT binaural interference (info from 2 different inputs)
Who can’t use AC HAs?
- people with congenital atresia, microtia, some otosclerosis, or single-sided deafness
- people with BAHAs
Bone Anchored Hearing Aids (BAHA)
- info sent via BC across skull to opposite ear canal to Aud. N.
- goes opposite way through skull to stimulate cochlea
- BAHA goes on bad ear (skull side)
- titanium implants
- skin penetrating abutment
- sound processor
adjustable components of HAs
- earmolds
- microphone
- electroacoustic parameters
- real ear measurement
Earmolds
- anchor HA to ear
- deliver sound from receiver to ear canal
- sized to accommodate HL degree
- usually bigger HL=bigger earmold
Telecoil
- aka: T
- pick up telephone signal
- HA will not work on “T” setting
Output limiting
prevents signal from becoming too loud for people with reduced dynamic range
Specifications for HAs electroacoustic properties
- output level (SPL)
- gain
- frequency range
- distortion
Gain
Concept: The amount of amplification a HA
provides when conversational
sounds enter the HA.
Greater the HL, the greater the
gain needed from a HA. The gain in
a HA can be adjusted
Effect for person with HL: If there is too little gain, person may not
perceive benefit from HL. If the gain is
too high, persons may reject HA
Frequency Response
Concept: Filters used to emphasize high vs
low frequency HL so that it
matches the shape of the
audiogram. Frequency response can be
adjusted
Effect for person with HL: If a person has a HF HL and has low
frequencies included in the signal
(meaning they are not filtered out), they
will most likely not like the sound of the
HA and could even reject it.
Output limiting
Concept: The maximum output of a HA
when a loud sound enters the HA
and the volume is turned all the
way up – especially important for
persons w SNHL who have limited
Dynamic range. Output can be
adjusted
Effect for person with HL: If a sound from a HA exceeds the
person’s tolerance for sound, then the
sound will be uncomfortable, potentially
damaging and may result in a person
rejecting the hearing aid.
Distortion
Concept: HAs can distort sound when
amplified, but the total distortion
should not exceed 4% . Distortion
can be adjusted
Effect for person with HL: If there is too much distortion, the
individual user will complain that the HA
is noisy and will not want to wear.
Cochlear Implants (CI)
- electronic device that can provide a sense of sound to a person who is profoundly deaf or severely hard of hearing
- bypasses a nonfunctional inner ear & stimulates nerve with electrical current
-surgically placed under skin & behind the ear
Important dates of CI
1985: FDA approved CI for adults
1990: FDA approved CI for kids
external parts of CI
- transmitter
- external magnet
- microphone
- speech processor
internal parts of CI
- receiving antenna
- internal magnet
- receiver
- electrode array (enter via ST for access to BM & put through RW)
How does the external CI work?
Directional mic: picks up sound, changes acoustic to electrical, electrical signal sent to speech processor
Speech processor: receives electrical info, selects & arranges sounds into codes, coded signal sent to transmitting coil
Transmitting coil: receives coded signals from speech processor & sends as an FM radio signal across skin via antenna under the skin
How does internal CI work?
Antenna: receives code from across skin
Receiver stimulator: receives signal from antenna & sends signal to electrode array
electrode array: receives coded signal, stimulates the nerve fibers which sends message to the auditory cortex portion of brain
Take home about CI signal - why this matters to SLPs & Auds
CI signal is inferior to normal hearing, so they need training & therapy to use it
CI process
- determine candidacy
- surgery (3-4 hours)
- Hook up (4 weeks in between hookup & mapping)
- habilitation/ rehab
- education
CI adult candidacy (18+)
- moderate to profound SNHL in both ears
- limited benefit from amp defined by pre-op test scores of <= 50% sentence recognition in ear being implanted & <=60% in opposite ear or binaurally
CI child candidacy (2-17 yrs)
- severe to profound SNHL in both ears
- limited benefit from binaural amp
- Multisyllabic Lexical Neighborhood Test (MLNT - speech pereception) or Lexical Neighborhood Test (LNT) scores <=30%
CI child candidacy (9-24 months)
- profound SNHL in both ears
- no medical contraindications
- limited benefit from binaural amp after a HA trial
- monitor auditory milestones
Factors affecting CI outcomes
- duration of deafness (one of biggest factors)
- chronological age
- other conditions (ex: meningitis - ossification of cochlea)
- functional/residual hearing prior to CI
- Speech & lang abilities (affects rehab, may want to use ASL+ CI)
- Fam support/structure
- expectations (parents may have higher expectations than CI can deliver)
- educational environment (mainstream school vs. school for the deaf)
- Cognitive learning style
Medical considerations for CI
Absolute contraindications (NO WAY implant): cochlear nerve aplasia, complete agenesis of cochlea
Relative contraindications (case by case): ossification (caused by meningitis), congenital malformations of IE, active chronic OM
Anatomic considerations: must have cochlear nerve, changes of technique can be used if partial IE malformation
Which ear to implant for CI?
- typically better ear is implanted
- ear free of OM
- patient preference
- if 1 ear can still benefit from HA, then worse ear can be implanted
- strong evidence for bilateral CIs in adults
CI surgery
- 3 (sometimes 4) hour procedure
- approval from 3rd party payer
- scalp shaved (mastoidectomy approach)
- Chochleostomy (electrode insertion in ST)
- Intraoperative monitoring by Aud ( make sure good connection b/t CI & BM
CI risks/complications
- bleeding
- infection
- meningitis
- facial paralysis
- tinnitus, vertigo
- ear numbness
- device failure; migration (<1% to 3%)
- magnet has to be surgically removed prior to any MRI
After CI surgery
- Hookup between external & interal parts takes 3 weeks
- mapping is performed after (performing dynamic range)
factors that affect CI outcomes - Adults
TIME: age at time of implant; pre-implant duration of deafness
HEARING: pre vs post lingual, etiology of HL, residual hearing prior to CI, appropriate device programming
BRAIN: neuroplasticity, medical radiological, cognitive ability, consistency of use
THERAPY: access to rehab facilities
OTHER: fam & vocational support, additional special needs
factors that affect CI outcomes - Children
- same as adults plus…
THERAPY: quality of educational & habilitative environment, mode of communication
OTHER: maternal education
Downsides of CI
- will likely hear sounds differently
- lose residual hearing
- may have unknown/uncertain effects
- may not hear as well as others with CI
- may have limited benefit of understanding speech & lang
CI microphone
- Picks up sound from
environment - Mic converts acoustic sound to an electrical
signal and sends to speech processor
CI speech processor
- Unit receives electrical signal
from microphone and
arranges the speech signal
into a code - Analyzes the speech signal into its frequency
components of speech (high, mid, low) using
band pass filtering concepts. Sound is also
compressed here based on individual
need.The amount of current is controlled by
the MAP that is derived from T and C levels
of individual
CI transmitter (coil & magnet)
- Unit receives the coded
electrical signal from the
speech processor - Sends the signal across the skin via radio
frequency waves and holds the coil in place
Receiver/Stimulator
/Electrode array
- Receives the coded electrical
signal from the transmitter
and sends signal to the
electrode array in the
cochlea.Electrode is implanted
alongside the basilar
membrane. - Electrical signals are allocated to each
electrode based on their place in the cochlea.
High frequency sounds get allocated to the
basal end of the cochlea. Low frequency
sounds get allocated to the apical end. Nerve
fibers get stimulated based on the which
electrode is activated
Adult AR
- sensory management
- instruction
- perceptual training
- counseling
Transtheoretical Model of Health Behavior Change
- provides info about predicting client attitudes in relation to smoking cessation, weight loss, & exercise behavior
- Stages of Change is a process where people vary n their “readiness to change”
Speech reading
- learn to use visual cues to supplement what is heard (especially in noise)
- not an easy skill to develop because articulators move so fast
- look at mouth movements, gestures, facial expressions, & physical environment
- NOT lip reading
Why do we look at speech reading?
predictor of who will benefit from CI
Why do we move our articuators?
to produce acoustically distinct sounds NOT visually contrastive movements
How much of spoken english is lip readable?
30-35%
What does speech reading NOT account for
coarticulation & stress effects
Stress
emphasis on words in a sentence or phonemes in a word
- ex: I didn’t say vs. i didn’t SAY
Coarticulation
phonemes are influences by the sounds around it
- ex: I have (haf) to go in & I miss (mish) you
signal code
place & visemes
Visemes
represent the facial expression related to pronounciation of certain phonemes
- phonemes that look identical on the mouth
- ex: thy vs thigh, /l/ -hidden in mouth, etc
Can speech reading be trained
Yes, & it’s an approach similar Auditory training
Analytic
- focus on the building blocks of spoken english
- bottom-up training
Synthetic
- focus on getting the main idea
- top-down training
Clear Speech
saying “ the ship left on a cruise” instead of “the shiplef ona twoweecruise”
Vocational Rehab Counseling
GOALS: enhance communication function, increased participation in community, increased participation in employment
- job coaches assist in securing needed therapies
Vocational Rehab Eligibility
- physical or cognitive impairment to impact employment
- ability to benefit fro VR services in terms of employment
- if they require VR services to prepare for, enter, engage in, or retain employment
- lack of awareness of own rights to accommodations
Assistive Technology
Hearing Assistive Tech (HAT) = Assistive Listening Devices (ALD) = Assistive devices (AD)
Why use HAT?
1: HAs aren’t enough
2: help people hear better
3: legislation
Why HAT? Physical factors affecting speech perception
- amount & type of noise in a room
- distance the listener is from the speaker & how close they are to the noise source
- reverberation characteristics (want low)
What signal to noise (S/N) ratio is needed for people with HL to hear as good as people without HL?
+15-25dB S/N (full boat) IDEAL
- half sunk: +6dB
- fully sunk: 0 dB - speech is fully competing with noise
Inverse Square Law
sound attenuates (intensity decreases) with distance
- lose 6dB of sound with every doubling of distance
Which sounds are heard from a farther distance
voiced>unvoiced
What length of reverberation negatively affects speech perception?
longer reverberation
HAT transmitter & receiver systems
- FM
- electromagnetic induction loop (t-coil)
- bluetooth
- Infrared (IR)
- hardwired systems
What do HAT transmitter & receiver systems do?
bring sound from a distance to listener’s ears
Frequency Modulation (FM)
enables HAs to wirelessly connect w/ external mic to improve speech signal listener (longer distance)
- uses radio waves (allocated stations for education)
- transmitter: radio station
- receiver: a radio
(FM) you can leave the room & still hear the presentation
true
(FM) system can be used inside and outside
True
(FM) must have a receiver to use this system
true
(FM) must have an HA to use FM
false
(FM) can use FM in multiple rooms in the building
true
(FM) I can use my FM receiver with your FM transmitter
true - ONLY if you’r on the same channel
Bluetooth
uses short range wireless tech (10m/30ft) & not suitable for long range listening venues
- enables HAs to wirelessly connect w/ cells, TV, computer, tablets w/ HAs & CIs or remote mics
- very high-frequency radio waves to transmit data
- creates binaural signal in HA or CI
Remote mics
wireless system that helps people hear & understand speech in noisy situations & over distances
- some RMs work together w/ HAs & others are made for those w/ some normal hearing
- transmitter: includes mic
- receiver: universal, integrated, stand alone
Infrared (IR)
uses invisible IR light (similar to TV remote controls)
- can be used w/ headphones or a neck loop to connect to HA or CI
- transmitter: emitter panel (like IR diode on remote; emits signal like a flashlight)
- receiver: lanyard
(IR) you can leave the room & still hear the presentation
false
(IR) can be used inside or outside
false (maybe at night)
(IR) must have a receiver to use the system
true
(IR) must have an HA to use IR
false
(IR) can use IR in multiple rooms in a building
true
(IR) I can use my IR receiver with your IR transmitter
true
Electromagnetic Induction Loop (Hearing Loop)
uses electromagnetic fields of energy
- loop provides a magnetic wireless signal that’s picked up by the HA when it’s set to “T”
- mic: PA system
- transmitter: created by a loop of several wires
- receiver: T-coil in HA
(Loop) can leave the room & still hear presentation
false
(Loop) can be used inside & outside
false - mostly indoor
(Loop) must have a receiver to use
false - just need a t-coil
(Loop) can use induction loops in multiple rooms in a building
true
(Loop) I can use my loop receiver with your loop transmitter
true
General HAT troubleshooting
- are batteries charged?
- what sources of interference are close by?
- Must have 1 free channel in between if 2 different stations are being used in rooms next door
Hard wired
pocket talker
- pros: low cost, flexible uses, easy to use
- cons: generic amplification, wired, unable to hear others
