Hearing Aids
External electronic devices (fit inside or behind the ear) used to help individuals with hearing loss by amplifying sound
Helpful but there are limitations
Hearing aid styles
Bone conduction aid
Behind the ear
Open fit/RITE/RIC
Int the ear & in the canal
Completely in the canal
Body aid
Disposable HA
Over the counter/ PSAPS
Bone conduction aid
Bypasses outer and middle ear
Delivers sound via vibration through mastoid
Candidate: Ear drainage; Atresia - inner ear but no outer ear
For people who have good IE fxn but have condition in OE that limits ability to use regular hearing aid (cholesteotoma
Behind the ear
Larger controls
2 components: unit and HA
Can be used with assistive listening devices
Less feedback, easy to clean, fewer repaired
Candidate: children
Speaker/ receiver in body of HA, additional unit w/ other devices
Open fit (RITE/RIC)
Very small BTW
Thin plastic tubing from HA to ear dome
Clear tubing - Open FIT
Wire inside tubing - RITE/RIC
No ear mold
Receiver in the ear/ receiver in canal - RTE/RIC, more popular less visible
In the ear/ in the canal
All components housed 1 unit
Enhanced amplification of high frequencies
Receiver placements allows less needed gain
Custom made
E - larger
C - smaller
Completely in the canal
Cosmetically appealing & easy to insert/remove
Reduction of occlusion effect & feedback
Sound localization improvement
Less gain needed
Elimination of wind noise
Candidate: usually adults
Fishing wire/thread = remove debris
Occlusion effect impacts HA use
Body aid
Built in battery - activated when opened
Low cost
Mild to moderate HL only
Automatic, pre set programs, no VC
Disposable HA
Can look like Bluetooth phone receivers
Programs for different listening environments
Cost: $300.00-500.00
Personal sound amplifying products - PSAPs
Good for moving in direction of actual hearing aid
Over the counter - limitations because only work for m
Over the counter (PSAPS)
Can look like Bluetooth phone receivers
Programs for different listening environments
Cost: $300.00-500.00
Personal sound amplifying products - PSAPs
Good for moving in direction of actual hearing aid
Over the counter - limitations because only work for m
Parts
Mic
Amplifier
Receiver
Battery
Ear mold
Microphone
Converts from acoustic to electrical signal
Sound waves move diaphragm back and forth
Coil attached to diaphragm also moves back and forth
Coil wrapped @ magnet
Oscillating coil over magnet creates current
Electrical signal sent to amplifier
Purpose - opt
Types of microphones
Omni-directional
-Pick-up sound in all directions; used in quiet listening situations
Directional mics
-Picks up sound from in front of listener
Dual mics
-Front and rear mics; best for listening in noise
Options in gain
General rule:
more HL - more gain
Calculation made by manufacturers
Measuring amount of amplification
Subtract input from output
Dynamic range
Range of human hearing from softest you can hear to loudest you can tolerate (individuals comfort level at an one particular freq (intensity of sound in relation to individual)
Is s challenge to address b/c:
-Inc threshold and reduced tolerance for loud s
Output limiting of HA
Prevents signal from becoming too loud
Addresses problems of recruitment
Limits maximum power output (MPO)
Sound amplified to up to some manufacturer setting
Must be adjusted for individual use
Variety
-If HA user complains of really loud sound you can as
Amplifier
Electronic device that increases the voltage, current or power of a signal
Reciever
Converts electrical signal to acoustic signal
Considered a small loudspeaker
-Delivers signal through tubing or earmold
-Speaker/ loud speaker
Battery
+/- Proper insertion
Harmful if swallowed
Minimize drain of battery
How long do they last? 3-22 days depends on HA type, battery, HA use
Come in 5 sizes
Ear molds
molds
Anchor HA
Deliver sound from receiver to ear canal
Sized to accommodate hearing loss degree
Custom-made to fit ear
Provide coupling to ear for HA
Style/size - full shell, skeleton, canal, RIC (occluding vs. non-occluding)
Causes feedback
Wax
Analog V digital
96% of HA's sold today are digital
Digital aka DSP
Circuitry may depend on severity of HL
Both can be programmed to individual needs
HA users harder adjustment to digital
-Analog can be made to go louder than digital
-Not happy with HA - referring back to
Circuitry
Main purpose is to make sound waves louder
Amplifies all sounds (speech and noise)
Users typically complain about noise
Most are still programmable
Generally less expensive
Can provide a lot of power
Microprocessor - DSP
Convert sound into digitized signa
Additional HA features
On-off
-Switch on vol wheel; opening/closing battery door)
Programming Switch
-Allows you to select which program to use
Audio input
Direct input from signal source; E.g., plug into television or radio, ipod
Telecoil
-Also known as "T"
-Pick up telephone
How HA works
Sound is picked up by mic --> acoustic signal from mic is converted to electrical signal (by moving diaphragm back and forth, coil)
Diaphragm is moving back and forth (attached to coil wrapped around magnet) as coil moves over magnet = generates E signal
HA features
Style
Microphones
Output limits
Earmolds
Circuitry
-Analog/ Digital
Specification for HAs electroacoustic properties
Output level (SPL)
Gain
Frequency range
Distortion
Output level
how much sound HA is giving to the person; don't want it to exceed comfort level. (Don't want too much SPL; could damage/ hurt)
-Determined with loud sound going through
-NOT IN FIXED LISTENING ENVIRONMENT
-Coming from HA
Gain
amount of amp someone gets when you're providing convo speech
-Different b/w output and input signal amp across freq.
-60 dB input on convo
Electroacoustic properties
Output sound pressure level (OSPL)
Maximum sound pressure level to ear
One measure of OSPL
-90 dB SPL input signal
-If 90 dB SPL in then what is output @1000 Hz?
Rule of Thumb: you do not want output levels to exceed comfort levels
Gain/frequency response
Comfort
You do not want output levels to exceed ... levels
Poorest
Greater grain needed for freq with ... thresholds
Total harmonic distortion
Amplitude distortions at 500, 800, and 1600 Hz
Rule of thumb: Usually not to exceed 4% distortion at any one freq
-Rules about how much noise can be present in HA
-Rules about specific freq: 500, 800, 1600
-NOT TO EXCEED 4% distortion rate at these freq's
Reasons for binaural amplification
60% of individuals with HL are fit with 2 HA's
Localization to sound source improved
Eliminates head shadow effect
Loudness summation adds signal received to both ears
Binaural squelch improves signal-to-noise ratio
BUT... Binaural Interference
Frequency range
range where HA provides gain for individual listener (relation to HL and individual...)
Assessing HA benefit
Subjective measure using self-report questionnaires
Benefit to HA user (S.O. teacher, parent etc.)
Satisfaction with using amplification
Use time - Data logging
Activity limitations still experienced
Participation restrictions impact role
Impact hearing l
Verification process
Informal assessment
Aided testing (warbled tones, speech discrimination in quiet/noise)
Rating of Loudness
Real Ear Measurement - Demonstration
Client input
International Outcome Inventory - IOI- HA
HHI- E or HHI-A
Real ear measurement
Objective measure
-Tube inserted in ear canal near eardrum; HA placed on top of ear
Measures sound pressure levels near eardrum
-Determine if HA is delivering target gain
Not always performed
-Ask families if this was performed; Really Important for Child
Funding sources
Medicaid
VR
Sertoma, Rotary, Lions
Local Speech and Hearing Clinics
Hear Now** (Starkey Foundation)
Reconditioned HA's
VA
Internet search
HA orientation
User learns: function and fitting, maintenance and storage, telecoil and telephone use, expectations and limitations, troubleshooting
User and audiologist set wear time
User receives printed information and DVD or online resources
Audiologist sets follow-
Cochlear implants
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 and stimulates nerve with electrical current
Implant is surgically placed under the skin behind the ear
Three main companies
Cochlear Corp. (Cochlear Americas), maker of Nucleus system devices
Advanced Bionics, maker of High Resolution devices
Med-El Corp., makers of Pulsar and Combi 40+ devices
Important Dates: 1990 & 1985
Main parts of CI
1 - ear hook w/ mic
2 - speech processor
3 - transmitting coil (takes signal and sends across skin)
4 - transmitter under skin
5 - Electrode
External parts of CI
Directional microphone
Speech processor
Transmitting coil
Internal
Receiver stimulator
Electrode array
Advanced bionic
Cochlear
Directional microphone
picks up sound, changes to electrical, E signal sent to speech processor
Speech processor
receives E info, selects and arranges sounds into codes, coded signal sent to transmitting coil
Transmitting coil
receives coded signals from speech processor and sends as FM radio signal across skin to receiver stimulator
Receiver stimulator
receives coded signal, sends signal to implanted electrode array
Electrode array
receives coded signal, stimulates the nerve fibers, and nerve fibers send message to the auditory cortex portion of brain.
Bandpass filter
Mic (picks up signal and converts acoustic to electric)
Ex: PT signal (500 Hz) comes into processor (band pass filter & amplitude compressors) - band pass - filter that only allows certain sounds through it - this one ^ is low freq BP filter
400 Hz signal
Low frequencies
acoustic stimulate apical electrodes, and therefore apically positioned neurons, i.e., those that in the normal ear would respond most to low frequencies
ow band pass filter (more basilar)
High frequencies
stimulate basal electrodes and therefore basally positioned neurons, those in the normal ear that would respond most to high freq (base)
high band pass filter (less basilar)
Children 12-24 months
o Profound SNHL bilaterally
o Limited benefit from appropriate HAs
o Lack of progress in development of auditory skills
o No medical contraindications
o High motivation and appropriate expectations
Children 25 months to 1 year
Severe to profound SNHL
Lack of progress with auditory skills
Limited benefit from appropriate HAs
Open Set Speech recognition
Varies by company, but typically poor
<30%
High motivation and appropriate expectations from child AND family
Children
Duration of Deafness
Chronological Age
Medical radiological
Other conditions
Functional/residual hearing prior to CI
S/L abilities
Family support/structure
Expectations
Educational environment
Cognitive learning style
Age: 18 years of age or older
Limited
Medical considerations
Patency of Cochlea
-Mondini
-Ossification
Neurofibromatosis
-Type 1
-Type 2
Enlarged Vestibular Aqueduct (EVAS)
General Health
Outcomes from surgery
Authorization for anesthesia
Approval from 3rd party payer
Ear selection
-Which ear? Bilateral?
Scalp shaved
-Mastoidectomy approach with facial recess
Chochleostomy
-Electrode insertion into scala tympani
Intraoperative monitoring
-Electric ABR - describ
Hook up
Guestimates" made based on threshold levels - not an exact science
Harder for children to find C level
As little as 12 months with a CI
Adaption to CI
Most obtain substantial benefit for understanding speech and recognition of environmental sounds
Some receive no benefit for understanding
Failure Rates of infernal devices
<1% to 3%
Still variable performance in children and adults
Possible variables?
Lo
Factors affecting outcomes
Age at time of implant
OA vs. YA
***Pre-implant duration of deafness
Pre vs. post lingual
Etiology of hearing loss - some people are poorer performers than others
Residual hearing prior to implant
Family and vocational support
Consistency of usage
Appropr
Trouble shooting
Turn device on/off
Visually inspect LCD panel (body) or function switch (ear level)
Check coil is in place/and functioning
Change battery
Check program selection
Check mic/sensitivity settings
Change headset cable
Change transmitting cable
-Different prog
Bone conduction implants
Sound transmitted through bone conduction to healthy IE, bypassing EAC and ME
Outpatient surgery
Titanium Implant surgically implanted under skin (mastoid)
External microphone connects to screw
On bone
Outpatient surgery
Screw that is surgically implanted
BAHA (bone anchored hearing aid)
Candidates
-Malformation of ear canal or ME (atresia, missing ME/ canal)
-Infection of ear resulting in draining ears
-Bilateral CHL
Cholesteatoma, atresia
-Unilateral SNHL
Sudden HL
Acoustic Neuroma
-History is important
What does it sound like
(CI)
-Robotic, harsh, muffled, buzzy/ "tinny, kazoo w/marbles in mouth, chipmunk
-Why does is sound like that? � # of electrodes, only certain kinds of freq that can pass through, one specific spot on BM represents low mid and high (one spot - several fre
Why are AlDs needed?
Legislation
-For adults; ADA mandates effective communication
Adults
-At work, lectures
-Leisure
-HL - unilateral, bilateral
Children
-IDEA - IEPs allow for device under technology
-Schools = responsible to supply additional devices needed beyond HA
-ADP
HAs not enough
speech perception NOT improved by HAs/ CIs alone!
Factors affecting speech
Amount and type of NOISE in a room
DISTANCE listener is from speaker and how close they are to noise source
REVERBERATION characteristics
Adults
-Speech perception
-Listening effort
Children
-On task behavior
-Speech understanding
-Reading
-Spelling
-Beha
Distance
Further away from sounds one is, softer amount of pressure exerted on eardrum, and thus less intense sound
Average speech is about 65 dB SPL or (50 dB HL) @ 3 ft from speaker
Inverse square law - drop 6 dB for every doubling of distance
At about 6 ft (1st
SNR
Children with HL need more favorable ...
Noise sources
Internal: shuffling feet, books, papers, desks, pencil sharpeners
External: hall/traffic/HVAC units/ assembly areas etc.
Unoccupied room noise levels: 44dB SPL (LAUSD 2005)
Occupied room noise levels: 52 dB SPL (LAUSD 2005)
Peaks observed at 67-72 dB SPL
Reducing noise
Keep noise out of room
Decrease noise levels and reverberation
Acoustically treated lower ceilings
Wall panels: cover at least half of wall surfaces porous and dense material to absorb sound
Carpeting bacteria resistant floor coverings
Tennis balls on fee
Reverberation
Sound (spoken and noise) that reflects off surfaces in classroom
Remainder of sounds that exists after source has stopped
Measured in amount of time that it takes a signal to stop vibrating and decay by 60 dB
Bottom line: the lower the reverberation time,
Different technology
Listening systems
-Group
-Individual
Phones
-Alerting -Amplification
-Visual text
Environmental sounds
-Auditory
-Tactile
-Visual
Television
-Personal amplification
Listening systems
Selection of device has to consider context in which the device will be used
-Setting
-Social
-Cultural
-Physical
In addition to devices, other components will contribute to successful use of the systems also. B/c no system will work perfectly 100% of the
Individual
Factors to consider in selection
HL
-Binaural or monaural
-Severity (dB) and frequency (Hz)
-Conductive or Sensorineural
-May fluctuate or be progressive
Age
Acceptance of loss
Speech reading ability
Speech aid/telecoil use
Knowledge of and comfort with A
Microphones
Factors to consider in selection
Lavaliere or lapel
-Most are omnidirectional - 360
Table top or conference
Placement is vital! - Effect of distance on sound
Sound that is amplified for listener is only as clear as what comes into the mic
Distance has sam
Transmitter and receiver systems
Factors to consider in selection
FM
Electromagnetic induction loop - T coil
Bluetooth
Infrared
Hardwired
All bring distance to listener's ear
Sound sent to transmitter to receiver via radio waves, light, or electromagnetic waves, Bluetooth,
Day: FM (radio
Coupling devices
Factors to consider: No HA/ telecoil (headphones; ear buds)
connect HA or CI to Receiver
HA w/ T-coil
Necklace; Silhouette
Other common methods
FM boot
Cochlear implants
If transmitter is sending light waves, receiver must be able to pick up light waves.
No nA/ no t coils in HAs
use headphones/ ear buds. Like plugging headphones into radio. Signal converted to E-energy and transmitted to speakers in headphones ? then converted into acoustic output sound waves
Has T coil
flip switch from 'mic' to 'T'. Signal is still converted to electromagnetic in receiver, coupler sends signal directly to T-coil of HA. ? HA converts E signal into sound waves ? sends individuals' ear canal
BETTER b/c sounds isn't being converted to acous
Telecoils
HA: mic vs. telecoil
Not all HAs have T-coils
T-coils aren't as sensitive as HAs
Proximity is important
Commonly found in telephones and speakers
Susceptible to electromagnetic interference
Not as sensitive as HA and requires vol to be turned up
Better T
Bluetooth
Bluetooth wireless technology - data transfer b/w 2 electronic devices
Very high freq radio waves to transmit data
Turns HA into wireless headset for smart phone, MP3, computer, tablets etc.
Creates a binaural signal
Some type of gateway device (streamer)
Frequency modulation
Uses radio waves
Transmitter
-Radio station
Receiver
-Radio
Best known system
Made up of transmitter, which can be thought of as a small radio station, and portable receiver comparable to FM radio
System transmits sound using FM radio signals
Easy to set
FM advantages
Very portable
Very easy to set up and use
Offers great flexibility of movement
Used indoors or outdoors
Appropriate for mild to profound losses
Receiver can be covered or put in pocket
No fluctuation in strength of signal
Popular in classroom and other pu
FM disadvantages
Receivers are required for everyone
Receivers vary in quality and durability
Potential for outside interference
72-76 MHz bandwidth allotted by FCC
Police band, construction walkie talkies, pagers
Receivers and transmitters must be on the same channel
The
Infrared
Uses infrared light
Transmitter-emitter panel
Like the infrared diode on a remote control
Emits signal in 60 degree cone-like a flashlight
Receiver
Like the infrared receiver area on a TV or VCR
TV headphones
Use infrared light to transmit signal across d
Infrared advantages
Compatibility: 95 kKz is industry standard
Home receivers can be used with public transmitters
250 kHz if high intensity lighting
No spillover means security
Can be used in adjacent rooms
Widest bandwidth and best sound reproduction
Appropriate for mild t
Infrared disadvantages
Receivers required for everyone
Must have direct line of sight
Can't cover the receiver or put in pocket
Indoor or evening use only
High intensity or fluorescent lights cause interference
Large areas require multiple emitter panels
Quality varies with com
Electromagnetic induction loop
Uses electromagnetic fields of energy
Power lines
Transmitter-Loop of several wires
Receiver
T-coil in hearing aid
Desktop receiver
Telephone and other speakers
As small as a neck loop or as large as an auditorium
Most difficult to explain; one of the eas
Induction loop advantages
Low equipment costs after installation
Easy operation
Lasts forever
Induction receivers are compatible with ALL loop systems
Unobtrusive with T-coil hearing aid
Long lasting
Easy to use (as long as T coils are functioning in HA)
Used in various situations
Induction loop disadvantages
Installation costs may be high
Installation may not be possible in historic buildings
Can't assume everyone will have a T-coil
Susceptible to electrical interference and spill over
Must sit around looped area
May be dead areas within loop
Installation in
Hard wired
The only hard-wired device you'll ever need ----Pocket talker
Pros
Low cost
Flexible uses
Easy to use
Cons
Generic amplification
Wired, not wireless
Unable to hear others
Troubleshooting assistive devices
Batteries charged? 3-6 hours
Deductive reasoning
Microphone?
Transmitter?
Receiver?
T-coil working? try it out with a phone call
Exchange components.
Purchase devices in pairs if possible
Ultrasonic sensors; Call the company!
Most obvious item to check is
Troubleshooting FM
Are the receiver & transmitter on the same station?
Color code or number them
What sources of interference are close by?
Station drift-your system OR someone else's
Police band, construction walkie talkies, pagers
Must have one free channel difference if
Troubleshooting infrared
Is the room bright, or is direct sunlight present?
Is anything blocking the line of sight?
Are high intensity fluorescent lights present?
Most common prob = maintaining line of sight b/w transmitter and receiver, and interference from night light
May not
Troubleshooting induction loop
Are there sources of electrical interference and spillover nearby?
Move seating to be closer to the loop.
Portable systems can be a mobility hazard. Are wires protected?
Moving to different seat can often help
Individual may just be sitting close to a sou