Exam 2 (Part 2) Flashcards
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
True
Less lf and mid energy, less audibility from 4-8 but bulk of the gain is right between 2-4 supporting the SII
na nl2
focused on loudness normalization and focuses more on sound quality
Add LF and mid frequency gain if sounds tinny
dsl
Your patient is desiring increased intelligibility?
choose nal nl2
Your patient is desiring increased comfort or their REUR is not average?
choose dsl 5
What does it mean when a prescriptive formula is proprietary?
It means that the formula was designed and is exclusively used by a hearing aid manufacturer.
how close the measured output is to the prescribed target.
root mean squared error
goals of verification
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.
difference b/w the probe measured output and prescriptive targets (500 Hz, 1k HZ, 2k Hz, 4k Hz)
root mean squared error
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.
5
Is it acceptable for an audiologist to change the prescription, applying gain that does not meet the “+/- 5 dB for target” criteria?
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
Loud speech signals are ____dB louder than the LTASS, therefore the top of the speech envelop represents loud sound
12
Soft speech signals are ____ dB softer than the LTSS, therefore the bottom of the speech envelope represents soft speech
18
SpeechMap input signal intensities are similar… soft= 50 to 55 dB; loud= 75-80 dB
true
for an input signal of 65 dB the loudest output arriving to the TM is around
77 dB SPL
for a 65 dB input signal the softest output arriving to the TM is about
47 dB SPL
When you adjust a band, you adjust
the entire speech envelope up and down
When you adjust a channel,
you either adjust bottom or the top of the speech envelope
how do we maintain balance bw the CR TKs
move bands, raise soft sounds, then raise loud sound
the upper intensities of the speech envelope may be audible when targets falls below a threshold
true
what are some programming pitfalls
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
what is acoustic transparency with probe module calibration
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
what is the max power output of the HA
OSPL90
ehadroom
channel interaction
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
Frequencies are tied together so adjustments made to one frequency pulls adjacent frequencies up or down
true
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
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
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
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
Aided output b/w ears must be within ____ dB SPL
15
ILD’s must be maintained by
HF audibility above 3k Hz
ITD’s are maintained by
LF audibility below 850 Hz
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
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
Research in the 1980’s found patients with severe to profound hearing loss preferred more gain and less HF emphasis
true
Formula Refinements for severe to profound HL (NA-RP)
Gain is calculated as 66% of the threshold loss rather than 46% of loss
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
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
Fit both ears and let PT experience and determine value of binaural amp when
Both ears may assist speech intelligibility to some degree
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?
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
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
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
bicros
If better ear has reasonable SNR loss and can benefit from ear level device using directional microphones
Lacks binaural benefit