Practical Flashcards
what are the goals of earmold impression
go 2mm beyond bend
stretch aperature
what should you do first for earmold impressions
wash hands
what is important before starting impressions
case history
what should you ask for case hx
have they had surgery on their ears? if so what?
are they taking any blood thinners?
are they diabetic or immunocompromised?
do they have any allergies
should you stand for otoscopy
no sit
foam block
slightly larger than EAC entrance
cotton block
same size as EAC entrance
what are you looking for on otoscopy after inserting the otoblock
Ensure block is tight in canal with no gaps - foam blocks should be compressed
Ensure removal string is in the center of the block not at an angle
what are otoblock precautions
Perf
Ensure NO GAPS present bw canal wall and block
PE Tube
Aggressive block depth may cause pain/damage
Mastoidectomy/Widening Canal
Might require more than one block to fill canal
If insertion beyond the isthmus suddenly becomes easier it is a clear sign of a widening canal
can you use gloves to mix earmold material
no
how to do a single open jaw impression
place in mouth horizontally on side of impression
how do you do a bilateral open jaw impression
place vertically in center of mouth
why do we do open jaw impressions
Increase size of aperture for a snugger fit - condyle of mandible moves forward and pulls the anterior canal wall
what are you looking for on earmold impression after removal
Are concentric circles present?
Is the valley filled?
Is the Concha cymba filled?
Is the Concha cavum filled?
Does material reach the otoblock?
*Does the canal length meet requirement/ patient’s needs
for earmold modifications what is the blue stone for
Course
Used to modify silicone
Need to use at least 25k to 20k RPM for best results
what is the white stone for for eaermold modifications
For grinding acrylic or vinyl
Smaller one is for smaller areas
low grit
removes a lot fast
medium grit
less material & smoother finish
fine grit
smooths & restores shine
only used w/ lucite/acrylic
Factors to Consider When Selecting a HA Style
Fitting range- can the style supply sufficient output?
Pinna effect- will the microphone placement enhance or reduce spectral cues?
Likelihood that the style will cause feedback or occlusion?
Wind noise-will the wind to produce turbulence inside the microphone?
Will the size of the patient’s ear canal limit the output or size of controls?
Will perspiration, cerumen, and humidity impact device function?
Realistic fitting ranges are impacted by
Proximity of microphone to receiver
smaller devices produce less output
Size of receiver
larger receivers produce greater output
Physical properties of sound bore (length, diameter)
Vent size
Microphone location
Proximity to tympanic membrane
Near normal low frequency hearing typically doesn’t require an amplified signal because the intensity of a “direct signal” is audible without amplification
true
what vent size should match 50-60 dB loss @ 500 Hz
.5 to no
what vent size should match 40-49 dB loss @ 500 Hz
1-2mm
what vent size should match 30-39 dB loss @ 500 Hz
2-3mm or power
what vent size should match 20-29 dB loss @ 500 Hz
3-3.5 mm or closed
what vent size should match </= 20 dB loss to 1.5 kHz
open dome
what is the OE
Increased perception of ones own voice when there is something blocking the ear canal
what causes the OE
Dome closing off the ear
Mold with a vent that isn’t large enough
what is feedback
too much amplified sound that leaks back out
what causes feedback
Too large of a vent = sound escaping and recycles back into the microphone
Creates a cycle/loop
Makes a squealing sound
Need tighter earmold or vent
As receiver gets closer to the mic -
less output = smaller devices because it drives feedback
what is the pinna affect
Pinna adds natural gain & spatial awareness cues & decreases wind noise
Effets boosts of HF signals by ~7 dB SPL
The deeper the microphone is in the ear canal the greater the effect
what type of HA gives the pinna effect
CIC/IIC
Combination of deep mic placement & deep fit device increase output by
~13 dB SPL
When volume b/w ™ & receiver reduces the output increases by
~6 dB SPL
what increases the devices output
sound bore proximity to the TM
what does an IP68 mean
IP68
Dust light
Protects against long periods of liquid immersion
-10 to 15 dB
nornal
15-25
slight hl
25-40
mild hl
40-55
moderate hl
50-70
mod severe hl
70-90
severe hl
> 90
profound hl
what degree of hearing does BTE fit
all
-10 to profound
what degree of hearing does slim tube fit
mild to mod hl
-10 to 55
what degree of hearing does ric fit
min to severe hl
-10 to 90
what degree of hearing does ITE full shell fit
normal LF to mod sev hl
-10 to 70
what degree of hearing does ITC fit
slight lf to mod sev hl
20-70
what degree of hearing does CIC fit
mild to mod sev hl
25-70
what degree of hearing does IIC fit
mild to mod severe
30-70
what is a cros HA
Contralateral routing of sound
Single sided deafness - one ear is normal and poorer ear is unaidable
One good ear and one bad
what is bicros
Bilateral contralateral routing of sound
Bilateral asymmetric HL - one ear has threshold loss & poorer ear is unaidable
Both ears are bad, asymmetry HL
for bicros or cros when the PT wears the devices will they get binaural hearing?
No because they still only have one ear and will not have spatial awareness
what is ampcros
For asymmetric HL
bad and better ear
bad ear is not good for hearing aids (poor discrimination etc.) but not unaidable
fits two HA’s on the PT’s ear but in the two is a transmitter so you amplify both ears but then also routing the poor ear over to the other ear for extra boost of understanding
when you fit HA’s to both ears but they also transmit a signal to the opposite ear
what loss is full shell for
challenging to insert
max retention
severe/profound - 70-90
high gain aids
skeleton mold
popular
easy to insert & discrete
max retention
mild to severe - 25-90
canal mold
easy insertion
cosmetically nice
retention needs 2mm beyond 2nd bend
mild to sev - 25-90
canal lock
easy insertion
cosmetics w/ retention
mild to severe - 25-90
half shell
easy insertion
easy retention
mild to severe - 25-90
all shells are mild to severe fitting except
full shell
fits to profound
when can an open dome be used
normal hearing to 1500 w/ HF loss
when can a closed/tulip coupler be used
thresholds </= 40 dB below 1000
when can a power dome be used
thresholds </= 40 dB below 1000
If HL 50dB or more in low frequencies you have to have
mold
what is an alternative to stock open dome couplers
custom open mold
who is vinyl good for
infants
those w/ dexterity issues
high gain devices
who is silicone good for
peds
high gain devices
allergiesw
who is lucite good for
adults
mild-severe loss
soft pinnas
advantages of vinyl
snug fit needed for high gain devices
cemented tube needs less canal space
easily modified
disadvantages of vinyl
shrinks
hardens
discolors
replace every 6-12 mos
advantages of silicone
durable
doesn’t shrink
hypoallergenic
snug fit for high gain
disadvantages for silicone
sticky material can cause discomfort
hard to modify
cannot glue tubing
more expensive
adv of acrylic
durable
no shrinking
easy insertion & removal
disadv of acrylic
cannot move w/ ear canal turns & narrowing
increased feedback w/ movement
physical injury if hit
common use of acrylic
adults
floppy soft pinnas
common use for vinyl
pediatric
firm ear texture
common use for silicone
high gain aids
allergies
facial flex issues
A change to the internal diameter will change the device output and frequency response
true
what is the diff bw 12 & 13 inner diameter?
12 is thicker and bigger opening
13 has a smaller opening
smaller diameter of inner tube =
more attenuation there is in high frequency signals
what is a tube lock
Used w/ silicone
Grommet used to increase friction fit into the mold
waht is a libby horn
gives a boost in the high frequencies
what is a continuous flow adapter
Small canals that can’t fit standard tube size
Keeps internal diameter of sound bore bw BTE & earmold to provide a continuous inner diameter & unimpeded flow of amplified signal
what is dry tubing and why is it used
Reduces moisture buildup problems in tubing in humid environments or those who perspire a lot
thin/heavy cement
lucite acrylic
uses vinyl cement
vinyl
walk through silicone retubing
Cut the tube where it enters the earmold as close as possible
Take the screwdriver tool and push the tubing out of the mold
Push the threader through the sound bore side
Feed the new tube through the needle with the quail side up & pull through the sound bore side
Make sure the new tubing has the grommet
Pull until the grommet meets the wall of the mold. DO NOT PULL FULLY THROUGH
Use tool to push and lock it in the sound bore correctly
Use the depth line on the tool for reference and push grommet in until it reaches that line
Cut the tube at the sound bore as close to the mold as possible without cutting the mold
Use the exacto knife
walk through retubbing of vinyl & acrylic
Take pliers and try to pull the tube out in one try
Use the reemer to push through the sound bore to make sure all pieces are out
Size the tubing
Once you find the right tube size, find the right cement
Lucite/Acrylic uses thin cement
Vinyl uses vinyl cement
Use a pipe cleaner and dip into the correct cementTake the needle threader and push through the sound bore side. Then take the quail side of the tube through the threader and pull through
Make sure the tubing is facing the correct angle
Drop a little cement as a final seal on the outside on the base side
Use the exacto knife to cut the sound bore tubing without cutting the mold. Check it doesn’t snag
Measurement mic that is sealed into the coupler and collects output data from the HA
coupler mic
Simulates ITE & ITC products
ha 1 coupler
BTE w/ hooks
ha 2 coupler
what is the OSPL 90- Output SPL @ 90 dB measured during ansi
This shows output for a 90dB SPL input signal (MPO)
Loudest possible output point device can produce for a 90 dB input signal & represents a single frequency
what is HFA OSPL 90- HF Avg output SPL @ 90dB measured in ansi
Calculates the average OSPL 90 output for 1, 1.6 and 2.5 kHz
*3 triangles at the bottom
what is HFA FOG - HF avg full-on gain measured on ansi
Shows avg gain for 1, 1.6, 2.5 for a 50 dB signal
Estimates the max gain available at different frequencies when an avg input signal is amplified
what is equivalent input noise (EIN)
Measures the internal noise of the HA
Noise coming from mic, amplifiers, DSP circuit, receiver etc.
Typically 25- 30 dB SPL is acceptable
what is total harmonic distortion
Measures signal distortion
Determines if output signal contains harmonic frequencies that were not present in the input signal
what is % total harmonic distortion
Should be below 5-10%
High DL are indicators the device is close to failing (most likely the receiver) & needs sent in for a repair
step one: look at manufacturer value on spec sheet
step two: look at summary of tolerances
step 3: look at data point; is it in or out of spec
true
what are the steps for looking at specs
step one: look at manufacturer value on spec sheet
step two: look at summary of tolerances
step 3: look at data point; is it in or out of spec
what is directional mic front to back ratio (FBR)
Compares output of an input signal coming from 0-deg azimuth to the input signal coming from 180-deg azimuth
what does directional mic test show
Heavy line - front mic output
Light line - back output at the null
what is digital noise reduction attenuation ansi
it acts on steady signals (fast modulation rates and low modulation depths)
Kicks in for signals that are louder than the first TK
Because it looks at the timing elements of the noise (fast mod rate & low mod depths)
what is SPLITS
shows output of tcoil in horizontal
what is RSETS
difference bw the mic and the tcoil output in horizontal
which measures telephone tcoil
horizontal magnetic field
SPLITS & RSETS
which measures looped t coil
vertical magnetic field
SPLIV & RTLS
SPLIV
output of tcoil (in vertical)
RTLS
difference bw mic and tcoil in verticle
horizontal t coil is best for
telephone
vertical t coil is best for
loop environment
what is the point in the TMFS test
This verifies output from the two transducers is the same & identifies which position the telecoils sensitivity is greatest
what is a +RSET
telecoil output it louder than the mic output
PT will turn HA down when telecoil is on
what is a - RSETS
telecoil ouput is softer than the mic output
PT will turn HA up when telecoil is on
T indicates mic is off & output is only from tcoil
open dome device
mT indicates tcoil & mic output is combined but mic output is softer
severe thresholds
MT indicates devices combines tcoil & mic output
equally
what is the largest battery size
675 (blue
what is the smallest ha size
10 (yellow)
what is the most comon size battery
312 brown
what is the purpose of a listening chekc
subjective eval of HA, will only pick up significant device malfunction, should perform electroacoustic measure to compare to manufacturer specifications
Listening for unusual distorted bad sounds
Is it linear or nonlinear
Is it directional or omn
what are the ling sounds
“ah”, “ee”, “oo”, “sh”, “ss”, “mm
why are ling sounds used
tests across the frequency range
what is linear on a ha
If there is no change in amplitude from soft to loud
what is nonlinear in a ha
Amplitude is louder for soft and softer for loud
how do you know its a directional mic
If you turn HA 360 deg and sound attenuates behind HA
how do you know its an omnidirectional mic
If you turn HA 360 deg and it doesn’t attenuate from behind
what is expansion used for
to lower the output of very soft sounds
CR <.9:1
what is WDRC used for
needed to get soft sounds louder & expand dynamic range
restores loudness perception
More sound added to soft signals for audibility, less to moderate signals and minimal to intense sounds so they are perceived as loud without causing discomfort
CR 1.1:1 TO 4:1
when is output limiting compression used
-need this to protect the ear from loud sounds
CR >/= 5:1
