Exam 2 (Part 2) Flashcards
1
Q
proprietary algs may not match PT needs or audibility they need for soft and moderate sounds and the etra output for loud sounds makes it more linear and sounds more clearer
A
True
2
Q
Less lf and mid energy, less audibility from 4-8 but bulk of the gain is right between 2-4 supporting the SII
A
na nl2
3
Q
focused on loudness normalization and focuses more on sound quality
Add LF and mid frequency gain if sounds tinny
A
dsl
4
Q
Your patient is desiring increased intelligibility?
A
choose nal nl2
5
Q
Your patient is desiring increased comfort or their REUR is not average?
A
choose dsl 5
6
Q
What does it mean when a prescriptive formula is proprietary?
A
It means that the formula was designed and is exclusively used by a hearing aid manufacturer.
7
Q
how close the measured output is to the prescribed target.
A
root mean squared error
8
Q
goals of verification
A
ensure that the measured output is as close as possible to those prescribed for the patient, and that the hearing aid provides adequate audibility of the important speech energy without feedback or loudness discomfort.
9
Q
difference b/w the probe measured output and prescriptive targets (500 Hz, 1k HZ, 2k Hz, 4k Hz)
A
root mean squared error
10
Q
An RMSE criterion of ____dB from prescriptive targets has been the precedent in academic research and is attainable for most mild to severe hearing losses.
A
5
11
Q
Is it acceptable for an audiologist to change the prescription, applying gain that does not meet the “+/- 5 dB for target” criteria?
A
Following the +/- 5 dB rule is a good general guideline but it is okay to make further adjustments based on the patients loudness or sound quality perceptions as long as the output follows the recommended prescriptive contour
match the line and shape of the targets that are present
12
Q
Loud speech signals are ____dB louder than the LTASS, therefore the top of the speech envelop represents loud sound
A
12
13
Q
Soft speech signals are ____ dB softer than the LTSS, therefore the bottom of the speech envelope represents soft speech
A
18
14
Q
SpeechMap input signal intensities are similar… soft= 50 to 55 dB; loud= 75-80 dB
A
true
15
Q
for an input signal of 65 dB the loudest output arriving to the TM is around
A
77 dB SPL
16
Q
for a 65 dB input signal the softest output arriving to the TM is about
A
47 dB SPL
17
Q
When you adjust a band, you adjust
A
the entire speech envelope up and down
18
Q
When you adjust a channel,
A
you either adjust bottom or the top of the speech envelope
19
Q
how do we maintain balance bw the CR TKs
A
move bands, raise soft sounds, then raise loud sound
20
Q
the upper intensities of the speech envelope may be audible when targets falls below a threshold
A
true
21
Q
what are some programming pitfalls
A
disregarding targets falling below thresholds
only adjusting frequency shaping band for 1 input intensity
avoid adjustin moderate channel input for 65dB signal during initial fit
If you increase gain without observing an increase in REM, stop adding gain
Not realizing MPO headroom limitations can result in unintentionally high compression ratios
Using too small a frequency range when adjusting to target
22
Q
what is acoustic transparency with probe module calibration
A
means that with the presence of the probe tube it doesn’t alter the sound that is being measured by the reference mic and allows us to still get an accurate measurement
So becuase the probe mic cannot physically go into the ear we use the probe tube to extend it but through the calibration protocol it adjusts the intensity differences removing the tube’s resonance effects, keeping the probe tube acoustically invisible so the measurements are not altered in the presence of the tube
23
Q
what is the max power output of the HA
A
OSPL90
ehadroom
24
Q
channel interaction
A
intending to make a change in one area but meet the limits of the change and you change CRs
Change a band up but you reach the MPO (black line), loud sounds wont get any louder but soft and mod will and instead of them being far apart with good CR, the lines squish together but didn’t intend to change CR
25
Frequencies are tied together so adjustments made to one frequency pulls adjacent frequencies up or down
true
26
too high MPO fitting
PT turn gain down - lack of audibility for soft and average inputs maies them conclude HAs don’t work well
PT may use them only in quiet settings - do not use them in many listening situations & conclude maybe HA’s are not useful at all
PT initial experience is negative and they stop using their HA’s
27
too low MPO fitting
Speech can sound distorted because it will often be at the MPO level
Speech might not have the necessary dynamics - peaks will get clipped, music sounds dull
Range of loudness perceptions will be limited - average and loud inputs may only differ by a few dB following processing
28
how can you fit MPO just right
First measure their frequency specific LDLs
Pulsed pure tones, 2-3 frequencies per ear
Enter these into REM to convert from HL to SPL
Raise MPO to 5dB below PTs SPL LDL
Confirm PT perceived sound as loud but okay rather than loud and uncomfy
29
Forgetting to switch calibration from concurrent equalization to stored equalization when there is a chance the amp signal can cause ref mic contamination
Results in overamplification in HFs because ref mic lowered the speechmap signal
30
Aided output b/w ears must be within ____ dB SPL
15
31
ILD’s must be maintained by
HF audibility above 3k Hz
32
ITD’s are maintained by
LF audibility below 850 Hz
33
Fitting strategies supporting binaural advantage
Fit devices on separate days to minimize the risk of overwhelming the patient.
Fit the better ear first
Fit the poorer ear second
34
Define asymmetric hearing loss
Asymmetric threshold loss: 3 adjacent frequencies of >20dB, 1 frequency >25dB
Asymmetry in speech intelligibility: if the speech signal audible frequencies arecritical to understanding
Asymmetric SNR loss: 20% difference is significant enough to consider it, kind of a quick clinical rule of thumb, not researched. recommends quick sin to be done at the assessment phase part of comp audio
Asymmetric discomfort levels: are tolerance levels significantly different
35
Research in the 1980’s found patients with severe to profound hearing loss preferred more gain and less HF emphasis
true
36
Formula Refinements for severe to profound HL (NA-RP)
Gain is calculated as 66% of the threshold loss rather than 46% of loss
37
Aid only better ear to provide clarity the user desires & consider cros or bicros devices when
Word rec is extremely impaired on the poor ear
Loudness sensitivity limits the ability to provide useful function
Signs of binaural interference are present
38
Aid the poorer ear to balance signal audibility and supply some degree of binaural benefit when
Better ear has near normal thresholds in critical speech ranges
39
Fit both ears and let PT experience and determine value of binaural amp when
Both ears may assist speech intelligibility to some degree
40
The audiologist must answer these questions:
Is the use of any amplification appropriate and the best option for this patient
Is the patient adequately able to communicate in real world settings with this option?
Is there a better solution than a hearing aid?
41
Discuss realistic expectations of benefits and limitations with the patient
Conduct unaided/aided unilateral/ aided assessments and share comparative test data
Sentence understanding assessments in quiet
Sentence understanding assessments in noise
REM audibility assessments
Aided loudness discomfort assessments
42
when is a cros used
If patient desires improved hearing when one ear is close to normal and the other is unaidable
Lacks binaural benefit
43
verification protocol for cros
Probe tube is placed on the better ear
Patient position: rotates to 45 degrees azimuth during testing
Audioscan is set to OPEN fit to prompt equalization of a STORED CALIBRATION signal
This is used to avoid reference microphone contamination
Audioscan setup:
Select “Single View”
Select the better ear as the test ear
Click on the “Audiometry” button and select “None” as the target rule
Enter a threshold to start test
Measure Speechmap REUR
Place BOTH Right and Left probe modules on patient
Set Audioscan style to BTE
Insert probe tube only into patient’s better (R) ear
Position patient @ 45-degree angle to the better ear, as depicted in front of the sound field speaker
Measure the output of a 65 dB SPL SpeechMap signal
Measure Head Shadow
Rotate patient position so POOR ear is @ 45 degrees azimuth
Change style to CROS hearing aid
Repeat measurement of 65 dB SPL SpeechMap signal
Note LTASS/speech envelop difference
Measure Cros Effect
With patient in the same position, place the transmitter unit on the patient’s head and activate
Repeat measurement of 65 dB SPL SpeechMap signal
Objective: Aided LTASS equals unaided LTASS because CROS transmitter eliminated head shadow effect
Want to activate the reference mic on the opposite ear so signal arriving to the poor ear is 65 dB
44
bicros
If better ear has reasonable SNR loss and can benefit from ear level device using directional microphones
Lacks binaural benefit
45
verification protocol for bicros
Style: CROS
Follows standard verification protocol for prescriptive targets are added for the better ear.
Position patient @ 45-degree azimuth to poorer ear
Dynamic range compression at 55-, 65-, and 75-dB SPL and MPO settings are verified “better ear”
These settings dictate HA performance for input form either microphone in a BiCROS system
46
ampcros
Combines traditional & CROS hearing aid features
Output is delivered to the poorer ear and routed to the better ear
Requires some degree of speech intelligibility in the poorer ear
May supply some binaural benefit
47
describe type I NIHL
represents the configuration after a few years of exposure
Normal or near normal to 2k Hz
Special fitting strategies aren’t necessary
48
describe type II NIHL
represents many years of excessive exposure to noise
Threshold loss extends into the lower frequencies (i.e., below 2000 Hz).
Use of typical fitting strategies may help if output supplies HF audibility
49
describe type III NIHL
represents the extreme case in which hearing is near normal for the low frequencies only
Threshold loss shows a precipitous slope into the high frequencies.
Special fitting strategies are needed to support success
50
Outer haircell (OHC) damage in the cochlea leads to abnormal loudness growth (recruitment)
true
51
Potential distortion for patients with damaged or absent inner hair cells (IHC)- Dead regions
true
52
what are challenges associated with Type I & II NIHL
OHC = recruitment
distortion possible with dead regions
HF output is limited by feedback
full HF audibility isn't reasonable due to comfort and sound quality problems
53
Large vents needed to release LF gain limits gain available in the high frequencies
true
54
Word recognition assessment may not in type II and III
Accurately reflect the impact of reduced audibility of critical speech cues
Show cochlear distortions resulting from frequency resolution, and temporal resolution
Show central auditory nervous system deficiencies or deficits in cognitive processing.
55
Pre/post fitting sentence-based speech in noise test comparisons are needed to identify individual
abilities and limitations.
56
fjitting strategies for type I and II NIHL
disable frequency lowering initially
strive for audibility in residual hearing frequency ranges (add less gain if thres are close to LDL - thresh x .2 = 65dB gain)
add 5-8 dB of gain to normal frequ range prior to precipitous drop
enable expansion to reduce mic noise when hearing is near normal below 2
verify audibility of s or sh
enable & adjust frequ lowering 4-6wks after first fit
57
older fitting guidlines for dead regions
Assume the presence of dead regions for thresholds >70 dB HL
Assume the presence of dead region for precipitous slopes >20 dB/ octave
avoiding adding gain to any frequency meeting these criteria.
Theory: adding gain in the area of dead regions results in degraded frequency resolution
58
Evidence finds dead regions are present in only ______f of individuals with hearing loss
1/3
59
Dead regions may be present at levels as low as
55 HL
60
Prevalence increases with only a 10 dB slope in
2-4KHZ region
61
Most individuals only have 1-2dead regions frequencies
true
62
Only ___% of this population has “extensive dead regions” (more than 3 dead regions)
3
63
what are extensive dead regions
more than 3 dead regions
64
fitting strategies for type III
Add gain to thresholds below 85 dB HL
Strive to achieve a balance audibility from 500 Hz up to 3k Hz,for thresholds below 85 dB HL
Add 5-8 dB of gain to normal thresholds just before the precipitous drop
This bump of audibilityfor normal thresholds benefits sound quality and intelligibility
Enable expansion to reduce mic noise when hearing is near normal below 2k Hz
Internal noise will cause patients to lower overall volume
If a threshold is near LDL, apply no gain or 1/5 the threshold (2% of threshold vs.46%)
65
a 5 dB SNR improvement improves intelligibility by
35%
66
a 1 dB improvement to SNR increases inteligibility of sentences by
6-8%
67
Full high frequency audibility is not a reasonable goal due to comfort and sound quality problems.
true
68
Full high frequency audibility is not a reasonable goal due to comfort and sound quality problems.
so what do we do?
Focus on supplying gain to heathier areas of the cochlea in the low and mid-frequencies
There’s no need to select a receiver offering wider frequency responses with extended high frequenciesl
69
lifestyle assessment
An informal assessment to identify technology level needed based on the person’s activity level (need more tech for more active lifestyle)
70
Maximize Audibility - An SII of 75% indicated the patient can hear 99% of sentences in quiet
SII
71
too many channels of compression reduces spectral contrasts bw vowels & consonants
true
72
try to maintain CR below ____ and balanced across _____ frequency ranges
2.5:1
3-5
73
other fitting strategies for cochlear regions
automatic directional mic enhances intelligibility
avoid too many CRs
select brands using true phase cancellation DFS
increase ear canal length to increase output ad decrease OE
74
DFS preserves HF output adding as much as ____ dB of gain in that area
10 dB
75
should we choose a receiver offering wider frequency responses with extended HFs
no
76
when do yo need special fitting strategies for cochlear dead regions
>3
77
what is the theory of FL in dead regions
shifting HF output to healthier part of cochlea improves intelligibility
Some did and some did not
78
when should you enable FL for adults
4-6 wks after fitting
79
what is the maximum audible output frequnency (MAOF) in FL
his is the region where audibility ends
Lower limit- the frequency where the LTASS becomes inaudible
Upper limit- the upper range frequency where the speech envelope becomes inaudible
80
how to assess FL candidacy
Disable digital noise reduction
Signal: calibrated /S/ presented at 65 dB SPL
Verify audibility: when the upper shoulder of the MOAF is audible with a DISABLED Frequency lowering
81
Enable FL to verify if audibility of a calibrated /s/ is achievable
adjust until upper shoulder is audible
allows approx 10dB audibility of the speech envelope
82
an “SH” signal is _____ Hz lower than the “S”
100
83
Too much audibility = poor sound quality
true
84
Goal is to add most amount of FL needed
false
least
85
spectral warping
copies the original HF signal and transposes it to the lower frequencies
Observe the original signal remains around 5k HZ and is pasted at 2k Hz
86
Increased prevalence of low frequency IHC loss and dead regions exist with
reverse slope SNHL
87
fitting focus with reverse slope snhl
focus on audibility within residual hearing regions (healthier regions of the cochlea)
88
what leads to unsuccessful fittings in reverse slope
Adding too much gain in LF = upward spread of masking
Satisfaction may be limited due to increased likelihood of extensive dead regions (>3 DR)
Note, digital “frequency raising” technology does not exist
89
digital “frequency raising” technology does not exist
true
90
how to fit reverse slopes
Add only 15-20 dB of gain in low and mid frequencies initially
Add 10-15 dB at 2k Hz & above of gain for increased audibility even if thresholds are WNL
Allow time for habituation before further increase
Some individuals may want more LF; some need less
Add more to MF and be cautious when adding LF gain
Once lows and mids are adjusted, modify HF based on individual’s perceptions
91
Additional gain is needed to overcome the attenuation caused by the mechanical loss
conductive losses
92
A/B gaps with normal B/C thresholds
compression is not needed because the dynamic range is normal.
Use of 1:1 linear signal processing (or very low CR) is fine
93
A/B gaps with abnormal B/C thresholds (mixed loss)
Compression is needed in addition extra gain due to the reduced dynamic range
94
which formulas add gain for a/b gaps
NAL does this automatically - MPO limits are not adjusted
DSL doesn’t compensate for addition gain needs
Each brand should be evaluated to identify limitations
Estat - takes BC into account - MPO limits are not adjusted
95
Calculating addition gain
for chl
add 25% of a/b gap to ac threshold
calculate gain recommendation for ac threshold
add 25% of ab gap
increase MPO by same % used for ab gap calculation allowing headroom for extra
96
Degree of loss =
perf size
97
Small perf (1-2mm)
minimal hl
98
Large perf =
25-35 chl
99
Total perf =
around 40 CHL
100
Posterior-superior w/ ossicular erosion
may result in a loss as great as 60 dB
101
options for perf hl
BC/Bone ancored devices
Some dislike surgical recommendation or are not candidates
Ear level device (HA’s, etc.)
Will the pathology allow for an ear level device?
What pathophysiologic concerns must be considered?
Style considerations?
Prescriptive considerations?
Verification considerations?
102
My not process complex speech inputs effectively due to degree of damage and amp experience
sev to profound
103
what may be cause of hl in sev/profound
mechanical and metabolic disruptions, membrane disruptions, large sections of inner hair cell loss, neural cell death, etc.
104
sev to prof have reduced reliance on audibili8ty. instead they rely on
alternative communication strategies which are supplemented by amplification
Amplification may be needed to support speech reading skills or for environmental sound awareness.
105
Patients may be more dependent on a specific signal processing type
Prefers linear vs. nonlinear signal processing
Prefers the signal processing of one brand
106
flexible fitting approach for sev to prof
Don’t rely on a targeted approach; begin with very low CR’s & listen to your patient instead
107
If they complain that speech is ‘muddled’, or indistinct modifications are needed
Change to slow acting compression to maintain a longer non-compressed state
Reduce compression ratios
FL may help
audibility of only signal above LTASS may be preferred
108
Slower acting compression approaches maintain more of the_____aspect of the speech signal over a longer periods of time.
linear
109
Verification Protocol for sev/prof
Use a prescriptive formula designed for this population (NAL-RP)
Begin by establishing their upper-level limits (LDL)
Reset MPO to LDL in fitting software to maximize available headroom
Evaluate audibility at 65 dB SPL
It’s okay if signal audibility below LTASS may not be possible
Verifying a 55 dB signal isn’t necessary
Use objective assessments to evaluate patient’s ability to extract speech cues
Sentences in quiet; sentences in noise vs. noise; sentence with speech reading
Follow guidelines on the previous slide when speech is described as muddled or indistinct
110
