1
Q
goals of earmold impression
A
Goal 1: go 2mm beyond
Goal 2: stretch aperature
2
Q
EMI Case History
A
Have you ever had surgery on your ear before? What kind?
Are they taking any blood thinners?
Are you diabetic or immunocompromised?
Do you have any allergies?
Silicone, lubricant ingredients
3
Q
otoblock size and placement
A
2mm beyond second bend
Foam block - slightly larger than EAC entrance
Cotton block - same size as EAC entrance
4
Q
what is viscosity
A
how easily the material flows before it cures; thickness
5
Q
high vs low viscosity
A
high:
Thick; more energy to force the material into the ear canal
Stretches the aperture of the ear canal for a better fitting earmold
low
Runny, loose
Flows easily with little resistance
Used for ear attenuation products & deep fitting HA
6
Q
Explain why it is important to stretch the aperture.
A
in order to get a well-fitted earmold
if we do not do this we get an uncomfortable earmold because the skin rubs against the plastic
7
Q
List the benefits associated with earmold canal that extends 2 mm beyond 2nd bend.
A
better HF gain & output
deeper canal fit gets the sound closer to the eardrum reducing resonant losses and improved HF sounds
reduced feedback
allows for more gain with less acoustic leakage
more retention & secure fit
engages the bony portion of the canal reducing the likelihood it slips out
reduced occlusion effect
When the canal portion extends into the bony portion of the canal, movement-related vibrations (like chewing or talking) are less likely to cause the occlusion effect
8
Q
what modifies silicone
A
Blue stone
9
Q
what modifies acrylic or vinyl
A
White stones
10
Q
BTE fitting range
A
- ALL degrees of HL
11
Q
slim tube BTE fitting range
A
Mild to moderate HL
-25dB to 55dB HL
12
Q
RIC fitting range
A
Minimal to severe H
–10 to 90 dB HL
13
Q
ITE fititng range
A
WNL to moderately severe
- -10 to 70 dB HL
14
Q
ITC fitting range
A
WNL to 500 Hz then to moderately severe HF HL
- Some LF HL to 70dB HL
15
Q
CIC fitting range
A
-Mild to moderately severe
-25 to 70 dB HL
16
Q
IIC
A
-Mild to moderately severe
-Best for those with LF HL
-25 to 70 dB HL
17
Q
Clinical use/limitations of each earmold material
A
vinyl
-Infants
-Firm ear texture
-High gain devices
adv
Easy modified
snug fit for high gain
dis: Shrinks, hardens, discolors quickly requiring replacement every 6-12 mos
Silicone
peds
high gain
allergies
ad: -Durable
-Doesn’t shrink
-Hypoallergenic for most
dis: costs more, hard to modify, discomfort
lucite
adults, floppy soft pinna
adv: durable, no shrink over time, easy to insert
dis: -Will not compress to move beyond narrow/tortuous areas
-Increased risk of feedback w/ movement
-Potential for physical injury if hit
18
Q
full shell fitting
A
max retention
Higher output for severe/profound HL
-70 to >90 HL
19
Q
skeleton
A
Mild to severe hearing loss
-25 to 90 dB HL
max retention
20
Q
canal
A
Mild to severe HL
-25 to 90 dB HL
need past 2mm for retention
21
Q
canal lock
A
-Mild to severe HL
-25 to 90 dB HL
retnetion lock gives more
22
Q
half shell
A
-Mild to severe HL
-25 to 90 dB HL
less retention
23
Q
50-60 dB loss at 5
A
.5 to no vent
24
Q
40-49 dB loss at 5
A
1-2mmvent
25
30-39 dB loss at 5
2-3mm or power
26
20-29 dB loss at 5
3-3.5 or closed
27
normal hearing up to 1.5 (
open dome
28
purpose of vents
to allow air and low-frequency sounds to pass between the ear canal and the outside environment. allows low-frequency sound (like the user's own voice) to escape, making speech sound more natural
reduces the occlusion effect ( "boomy" or echoey sound people hear when talking or chewing while wearing a tightly sealed earmold)
preserves residual hearing
29
Primary frequency range affected by vent effect
below 500 and up to around 1000Hz
30
Meaning and clinical usefulness of ingress rating
indicates the degree of protection a device has against:
Solids (like dust)
Liquids (like water, sweat, humidity)
important when selecting hearing aids for patients based on their lifestyle, occupation, or environment
31
Simulates the size of the ear canal when a custom product is inserted
ha1 coupler
32
Traditional BTE devices w/ earhooks
ha2 coupler
33
what is the reference mic in test box
Calibrates the SPL output from the test box speakers
Monitors signal intensity and automatically adjust speaker volume to maintain appropriate intensity
34
what is the coupler mic
A measurement microphone sealed into the coupler that collects the output data from the hearing aid
35
what is full on gain
average gain for 1k,1600,2500 Hz
Estimates the maximum gain available at different frequencies when an average input signal is amplified
36
what is reference test gain
This resets the device to 17dB below HFA OSPL90
37
OSPL90
output for a 90 dB SPL input signal to identify the loudest possible output point the device can produce for a 90 dB input signal
helps determine maximum output for the patient to not exceed LDL
38
HFA OSPL 90
HF average output SPL at 90dB
Calculates the average OSPL 90 output for 1, 1.6 and 2.5 kHz
*3 triangles at the bottom
39
Total Harmonic Distortion
determines if the output signal contains harmonic frequencies that were not present in the input signal. (@ 500, 800, 1.6hz)
Measures signal distortion
Should be below 5-10%
40
what does a high total harmonic distortion mean
device is close to failing (most likely the receiver) & needs sent in for a repair
41
Equivalent Input Noise
to measure the internal noise of the HA coming from microphone, amplifiers, DSP circuit, receiver
Normal = ~25-30 dB SPL
42
what does telecoil use
induction?
43
noise reduction measure
bold line and light line (directional mic) Bold line is the initial output measurement and the thin line is the level of attenuation as directionality is applied. It shows the difference of FRONT BACK mic RATIO
Compares output of an input signal coming from 0-deg azimuth to the input signal coming from 180-deg azimuth
Difference in output represents “FBR”
Larger differences (FBRs) suggests a greater directivity index is achieved to improve SNR & speech understanding in noise
44
Telecoil Magnetic Field Simulator TMFS
An electromagnetic test signal is emitted from the TMS at the source (T) in the test box. Place the coupler over it, and it will measure the output
45
SPLIT- SPL for an inductive simulator
horizontal/phone)
the output measurement of the TMFS signal
The measured output of the hearing aid
46
RSETS Relative simulated equivalent telephone sensitivity
horizontal/phone
difference between the SPLITS output and the microphone’s output when the device is set to reference test gain
47
+ RSETS
telecoil output it louder than the mic output
PT will turn HA down when telecoil is on
48
- RSETS
telecoil ouput is softer than the mic output
PT will turn HA up when telecoil is on
49
SPLIV
vertical/loop
SPL in a vertical magnetic field
measures the output of the telecoil in a vertical position to verify output for a looped environment.
Verify with summary of tolerances and manufacturer spec sheet to ensure hearing aid performance is good
50
RTLS
The difference between the microphone and the telecoil
Same as RSETS above
51
What does the test mic do?
52
What signal is emitted from the T in the box
Electromagnetic
53
REFERENCE mic
monitor and calibrate soundfield speaker output, maintaining desired signal intensity
54
Retention cord
stabilize and maintain the reference mic’s position
55
probe tube
measure the intensity of the signal arriving to the ™
56
collects and measures sound from the probe tube attached to it
probe mic
57
REUR
natural response resulting from the pinna and ear canal
58
Constant depth method
Pre-measure prob mic to average intertragal notch to ™ difference
Male: ~30mm
Femal: ~28mm
Peds: ~20-25mm
59
Acoustic method
On Testbox, select “Tests → On ear measures → Speechmap” and under speechmap, change #1 to Pink noise @65 dB SPL
Leave pink noise on as you insert the probe tube and observe the HF notch
Once HF notch is not dragging gain curve down (-5dB) then it is w/in 5mm of the ™
MOVE PROBE MARKER INTO POSITION ONCE PLACED
60
REOR
measurement of insertion loss caused by placing an earmold/dome in the ear canal
Verifies vent effects, slit leaks, transparency of open fit domes, and if the coupler meets the PTs Rx needs
61
RECD
Difference bw SPL resonance of a 2cc coupler and that of the real ear or ear canal resonance
62
Meets ansi standard, #1 standard for RECD
HA-1
63
pink line on RECD
real ear measurement
64
green line on recd
calibration of recd
65
dots line on recd
HA-1 RECD avg
66
blue line on recd
HA-1 RECD
67
if blue recd is below avg recd
larger than average ear canal
68
if blue recd is above avg recd
smaller than average ear canal
69
When pink goes below green in LF
slit leak = acting like a vent effect = poor seal = sound leaking out
Loose fit earphone: fully expand, increase tip size, apply aquaphor
Loose fit earmold/large vent: LF sound leaks out around it and causes negative RECD values below 1000 Hz
Perforations or PE tubes are present
70
Negative RECD >10dB in the 4-6 kHz region
probe tube blocked
71
Decreases RECD transform fxn in mid to highs
open mastoid cavity
72
Increase RECD transform fx in mid frequencies
MEE
73
what is happening in this image
Showing RECD responses for in tact ™ (left) and per (right)
74
what is happening in this image
Improper probe tube insertion (HF above 3,000)
75
what is happening in this image
Blocked probe tube (wax, tube against canal, tight earmolds)
76
developed by manufacturers
Proprietary formula
REM targets aren’t available, but NAL-NL2 targets can be used
77
NAL-NL2
Loudness equalization formula - balances perception of loudness over a range of frequencies (LFs have more energy than HF so this increases mid and high intensity until energy equals the lows)
Uses REIG targets
Provides targets for tonal languages
If PT is desiring increased intelligibility
Adults only
78
NAL-RP
(revised; profound)
79
DSL 5.0
Loudness normalization formula - maximizes audibility to assist language development
Uses REAR output targets (soft, moderate and loud are increasted)
Provides targets for MPO
Milder thresholds - low TK (~30 dB SPL)
Severe thresholds - higher TK (~60 dB SPL) - too much gain of soft results in loss of intelligibility here
Supports language development
PT is desiring increased comfort or their REUR is not average
Adults and kids
80
Expansion
Manages intensity of very very soft input signals & circuit noise
CR
Really low, lower than linear
<0.9:1
0-20dB
81
Wide dynamic range compression (WDRC)
AGC-i: input compression
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
Increases soft sounds and expands DR
TK
Low, bw 20-50
CR
1.1:4.1 (low)
Slow AT & RT
82
temporal fine structure preserved in speech signal
slow attack time
83
reduces times of inaudibility to very soft consonant sounds after compressor releases
slow release time
84
Output Limiting Compression (OLC)
Protects the ear from loud sounds
AGC-o
Output compression
TK
High, ≥80dB
CR
High
≥5:1
Fast AT, variable RT
85
protects from loud sounds
fast AT
86
sudden noises
Fast RT
87
sustained loud sounds
slow RT
88
what happens if there is too much audibility of /s/ sound for FL
poor sound quality
Goal is to add least amount of FL needed
89
tell me about QuickSIN
Speech intelligibility in noise remains the #1 improvement patients seek with hearing aids
Instructions
“Imagine you’re speaking to a woman while walking towards crowded party. At first, the woman’s voice is easy to hear because the party is far away. However, as you get closer to the party it become more difficult to understand her. At some point it may become impossible to understand what she say. It’s ok to take a guess.”
Procedure
If PTA <45 dB present word lists at 70 dB HL
When PTA >45 dB present sentence lists at an intensity perceived as “Loud but OK”
Channel 1
Ext A
Avoid use of Lists 3, 4, 5, 7, 13, and 16
Scoring
To get total SNR loss add up all 3 SNR total runs and divide by 3
Counseling
“This test realistically simulates a social gathering to measure your ability to ‘tune into a conversation’ in multi-talker environments”
90
what is happening in this image
91
which is audible to the PT
92
Standing waves
Worried about the cancellation of certain frequencies and resonance with an ear canal
If probe tube is not within 2mm of the ™, HFs are most likely to be out of phase leading to a drop and attenuation of HFs
In tubes, ear canals, whenever there is a closed space
In phase and out of phase signals
Brain automatically in all situations think about these points
93
tell me about ANL
Quantifies a listener's willingness to listen to speech in the presence of background noise
Predictive of hearing aid satisfaction with 85% accuracy
Identifies those who will have more difficulty adapting to amplification
Instructions- see image
Presentation
Binaural in SF at 0° azimuth
Calibrate - track 2
Set up
Channel 1 - speech - ext a
Channel 2 - noise - ext b
*both same speaker
Protocol
Turn Channel 1 on (with Channel 2 OFF)
Establish MCL
Increase speech in 5 dB steps until it is described that speech is too loud (provide with categories)
Decrease speech in 5dB until speech is too soft
SWITCH TO 2 DB STEPS NOW - increase speech until you reach person’s MCL
Note the MCL intensity
Turn Channel 2 on (Keeping Channel 1 ON)
Establish BNL (background noise level) - level of noise a patient can tolerate while still listening to and understand the signal
Noise here is intolerable
*MAKE SURE MCL DOESN’T CHANGE (it is fine if it does until we end this step)
Increase noise in 5dB until the story is incomprehensible. (BNL masks speech signal)
Decrease noise in 5dB until story is very clear
SWITCH TO 2DB STEPS (adjust mcl if needed) - Increase noise until PT can hear passage but they do not want anymore noise - as much noise as they can tolerant and can still understand
Note BNL intensity
Scoring
MCL value – BNL value = ANL score
Low ANL score (difference < 7 dB)
Indicates the patient ACCEPTS a lot of noise background noise w/o issues
This patient is likely to wear hearing aids on a regular basis
High ANL score (difference > 13 dB)
Indicates the patient LACKS TOLERANCE for background noise
This patient is less likely to wear hearing aids regularly
Premium technology
ANL scores b/w 8-12 dB are equivocal
May require extra post-fitting counselling or adjustment period
Counseling
“This test where I had you face the speaker and noise and a story was coming out at the same time allowed me to test your tolerance level of background noise. Do you find that you are bothered by this easily or it takes a lot before it does?
Yes bothered easy - this test and the results confirmed this and showed me that you do
No - this test and the results confirmed this and showed me that it takes a lot of background noise before it bothers you.
94
Sound bore internal changes and how it changes output characteristics
Choosing the wrong parameters in the software then you cannot successfully fit a patient
95
DSL5.0 vs NAL-NL2
DSL has more HF information, used with kids
NAL-NL2 has gain for CHLNAL-NL2 has targets for tonal languages
96
When you adjust a band, you adjust the
entire speech envelope up and down
97
When you adjust a channel, you either adjust
bottom or the top of the speech envelope
98
move bands, raise soft sounds, then raise loud sounds
maintain balance bw all the CR TK
99
Further lines go apart in software
more linear
100
The closer the lines are in software
more compression is added
101
shifting tk up reduces soft sounds
trued
102
shifting tk down increases soft sounds
true
103
Party Noise/Weddings
Increase HF CR slightly
Raise HF TK to 60dB
104
Paper Crinkling
Reduce loud channel for all frequencies
105
Toilet Flush
Decrease LF loud channels
106
Water running
Decrease MPO
107
Utensils
Lower loud channel for all frequencies
108
Dishes clattering
Decrease loud HF gain to increase CR
109
HF Weighted background noise (appliances, water running, blenders)
Increase LF band under 1500 Hz
Decrease HF band above 1500 Hz
110
Speech in LF noise (Malls)
Decrease LFs below 1500 Hz
Increase HFs above 1500 Hz
111
Comfort listening in LFs
Increase HF CR by 1-2dB
Rase LF TK 50 dB below 1500 Hz
112
HA is booming
Decrease LF bands gain
Decrease overall gain & MPO
113
“I can’t hear well with HAs”
Increase overall gain & HF gain & MPO
114
A is too soft/not loud enough
Increase overall gain & mpo & LF bands gain
115
Increase overall gain & mpo & LF bands gain
Increase vent size
Increase LF bands gain
116
identify the landmarks of an earmold
see image
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