Midterm 2 Flashcards
REUR/G
real ear absolute response/gain
Ex. REUR 53- input of 50= REUG of 3
*Measures the natural amplification created by the shape of the pinna and OPEN ear canal
REUR: REAL EAR UNAIDED RESPONSE–> The measurement of the absolute SPL level of an OPEN ear canal resonance, across all frequencies at the TM (input+gain+resonance=output)
REUG: REAL EAR UNAIDED GAIN–> the measurement of the gain added by the pinna shape and head diffraction effects and ear canal as measured in an open ear canal
REOR/G
Real ear OCCLUDED Measurement of INSERTION LOSS *attenuation occurs with the hearing aid in place and turned off
REOR: a measurement of the attenuation of an input signal, across all frequencies, when a hearing aid is inserted and turned off
REOG: A measurement of the difference in input & output SPL (gain reduction), across frequencies, when the hearing
aid is inserted and turned off
REAR/G
Real ear aided response: the frequency response and absolute aided output of an ACTIVATED hearing aid *changes based on depth of the coupler placement
REIG
Real ear insertion gain Measures the amount of GAIN needed to overcome the insertion loss (REOR) and restore audibility of the signal *The difference between the AIDED response (REAR) and the UNAIDED response (REUR) of the ear canal REAR-REUR=REIG
Why do we measure RECD?
- Accurate audiometric conversion of a threshold measured in dB HL using inserts to dB SPL values
- RECD creates personalized conversion factors for precise HL to SPL audiometric conversion
RECD
Real ear to coupler difference The difference between the SPL resonance of a 2cc coupler and the SPL resonance of the real ear *the pink and green lines, shouldn’t have a huge gap
If the acronym ends in R…
RESPONSE, represents an absolute measure of the SPL output arrive at the TM
If the acronym ends in G…
GAIN, represents the difference between the output intensity and the input intensity Output-Input=Gain
Why do we do REUR?
improves accuracy of prescriptive fitting by knowing an individual’s ear canal resonance It changes by ear canal differences:
- size, texture, shape, or presence of abnormal anatomy
- age: pediatric, adult, elderly
- one person can have 2 different REURSs
Estimate of insertion loss based on vent size
0mm: completely occluded ear mold, no vent, getting occlusion and attenuation in low frequencies, attenuation gets stronger and insertion loss gets larger in high frequencies
large vent: release low frequency energy and attenuate high frequencies
Why do we do REOR?
*won’t know if there is a slit leak unless you test this
1. to identify which low frequencies will be released through the vent *any gain you try to add in the frequency range of the vent effect will not increase the output, it will get released through the vent
2. To determine if the vent introduced
undesired standing wave effects that
would impact amplification
characteristics
Why do we do REAR?
To view device’s absolute output in a unique ear canal DSL prescriptive target specifies REAR (OUTPUT) targets for signals arriving to the TM *DSL is commonly used in pediatrics, good for non-average ears *NAL is commonly used in adults
Why do we do REIG?
We adjust GAIN for soft, moderate, and loud input signals within the programming software to achieve REIG NAL prescriptive targets specifies REIG (GAIN) targets to ensure loudness equalization is maintained
REAR 85/90
Real ear aided response/MPO *use either 85 or 90 dB signal, 85 if it’s directly on patient’s ear or 90 in test box measures intensity of the output signal (MPO) arriving at the TM, when the input signal is sufficiently intense to drive the device to its maximum power output level
How does an SPL-ogram differ from an audiogram. Why will measurement of the RECD improve the accuracy of the conversion?
The SPL-ogram converts the thresholds to an ascending loudness representation of loudness. The RECD can be a more accurate representation of the hearing condition and the treatment needed than an HL audiogram ever could. The dotted line at the bottom of the SPL audiogram grid represents the
average minimum audible sound pressure level. * show frequency specific LDL’s
What is the measured SpeechMap REAR representing? Be prepared to describe the speech spectrum envelope and LTASS factors that are visible in the REAR.
REAR shows the degree of aided audibility achieved.
The green shaded area is a REAR using a 65 dB SPL input signal. The difference between the gray shaded area and the green shaded area represents the measured change in output between the unaided and aided conditions.
LTASS Speech Envelope: Visual representation of modulated speech sounds. Speech envelope has a crest factor of +12 dB & valleys of - 18 dB. These two lines define the representative dynamic range of normal
conversational speech over time (a 10 sec. measurement)
Calculate threshold-based insertion gain requirements using the “half gain” fitting formula
“half gain”: most people wanted gain that equaled 1/2 the threshold of the loss (take loss and divide by 2, tells you amount of gain)
Differentiate frequency shaping band adjustments from compression shaping channel adjustments
“Frequency-shaping bands” increase or decrease “gain” until the prescriptive target is reached. Gain is adjusted as a frequency shaping band until output matches prescriptive target. COLUMNS, done first
Compression shaping channels are adjusted until the prescriptive target for THAT input level is reached. ROWS
Prescriptive targets
specify the REIG (GAIN) or REAR (OUTPUT) needed at each audiometric frequency Verification: the process that lets us see if our prescriptive formula provided the output we wanted!
Validation: the process that lets us see if the patient thinks our choices were beneficial
RESR
(Real ear saturation response) the frequency response of a hearing instrument, measured in the ear canal, with an input signal sufficiently intense to operate the hearing instrument at its MPO (watch patient’s face!)
REUR: test protocol and objectives
*HL
- Insertion gain
- enter instrument style
- Set PRESENTATION to SINGLE or
DOUBLE view - Set FORMAT to GRAPH (not CHART)
- Set SCALE to HL
- enter audiogram thresholds
- select transducer used in testing
-set REUR to MEASURE
-enter thresholds
*improves accuracy of prescriptive fitting by knowing an individual’s ear canal resonance It changes by ear canal differences
REOR: test protocol and objectives
*SPL
- with earmold in, make sure HA is off
1. on ear
2. speech map
3. format: graph
4. hide/show box: unaided–> show
To verify: the degree of vent effect, actual transparency of open dome fit, and degree of occlusion
Green: unoccluded
Pink: occluded
Occlusion Effect test: test protocol and objectives
-Vent management options
“Occlusion” scale indicates the degree of occlusion in dB SPL
Instructions:
1. Insert probe tube in canal
2. Place device in ear- muted or off
3. Patient vocalizes “eee” at moderate vocal effort
4. Press “stop test” to capture OE
Vent management:
OE reduces by 4 DB for
every 1 mm increase in
vent diameter
*if there is a small difference between probe mic and reference mic and its green, then there is no occlusion. If it is red and there is a big difference, there is occlusion.
Purpose of adjustments to frequency shaping bands vs. compression shaping channels
-protocol associated with each adjustment
“first fit” isn’t good
Frequency shaping bands (COLUMNS)=AUDIBILITY
“target matching”: highlight all gain values and raise and lower them as needed, adjust the overall gain until the LTASS falls within +/- 5 dB of a target
Compression shaping channels : adjust compression ratio to optimize detection of soft input signals or reduce loud input signals for increased comfort (ROWS)
MPO: test protocol and objectives
Purpose: to ensure tolerance of loud input signals
*Patient says loud and comfortable or loud but okay
Interpretation of SpeechMap speech envelope graphic response
If we adjust gain for a 50dB input signal, the bottom half of the speech envelope is adjusted.
If we adjust gain for a 75dB signal, the top part of the speech envelope is adjusted.
Which prescription provides targets for tonal languages?
NAL-NL2
*Low frequencies are more important in these languages
Which formula supplies MPO targets
DSL (Desired Sensation Level)
Loudness Normalization rationale and prescriptive formula approach. Which prescriptive formula follows this philosophy?
Theorizes aided loudness perception should be the same as the
normal loudness perception.
DSL (desired sensation level)
DSL formula settings for mild vs. severe hearing losses; pediatric vs. adult?
- Sets a low TK (~30 dB SPL) for milder losses
- Sets a higher TK (~60 dB SPL) for severe hearing loss
- Applies of expansion to low input levels
- Uses multi-stage WDRC compression to expand DR
- Uses output compression limiting to high input levels
DSL 5.0’s adult fitting formula version reduces mid-frequency gain by 7 dB
Loudness Equalization rationale and prescriptive formula approach. Which prescriptive formula follows this philosophy?
Theorizes aided loudness of high frequency signal should be equal to low frequencies, even if perceived loudness is different than normal loudness
perception.
This formula adds more gain to HF input signals, so they seem as loud as low
frequencies. This boosts high frequency output to improve audibility of high- frequency sounds
NAL (National Acoustic Library)
NAL formula for REIG settings for mild to moderate vs. severe losses
It uses pure-tone threshold to create REIG “gain targets”
NAL-R is better for mild to moderate HL because people with severe to profound HL require additional gain and less high frequency emphasis.
NAL-RP is better for severe losses because they required more gain and less high frequency emphasis. More low frequency gain provides power and less high frequency gain helps to deal with feedback issues.
Which formula supports language development?
DSL 5.0
- Sets a low TK (~30 dB SPL) for milder losses
- Sets a higher TK (~60 dB SPL) for severe hearing loss
- Too much gain of soft input signals results in a loss of intelligibility for this population
- Applies of expansion to low input levels
- Uses multi-stage WDRC compression to expand DR
- Uses output compression limiting to high input levels
- DSL 5.0’s adult fitting formula version reduces mid-frequency gain by 7 dB
What does it mean when a prescriptive formula is proprietary?
Each brand has their own “name-brand” prescription
Is it acceptable for an audiologist to change the prescription, applying gain that does not meet the “+/- 5 dB for target” criteria?
Yes because they are asking the patient what they think needs to be adjusted and the prescription is just a starting place
Patient desires increased intelligibility
Choose NAL-NL2
Patient desires increased comfort or REUR is not average
DSL 5.0
Audibility SII Scores
conversational, 65dB signal: ~70% SII
soft, 50dB signal: ~35-40% SII
loud, 75dB signal: Threshold +LDL/2= target for loud signals
REMEMBER:
Always adjust frequency shaping bands first, and compression shaping channels second.
Always select the broadest frequency range possible when you adjust program. Don’t forget to include all the low frequencies and high frequencies.
Consider which portion of the speech envelope you’re changing with each adjustment
Top of envelope: 75 dB
Bottom of envelope: 50 dB
Define channel interactions. Keep in mind that adjustments to one channel will impact adjacent channels
The slope of one frequency channel overlaps adjacent frequencies
Channel interaction: occurs when adjustments to one frequency pulls down adjacent frequencies
Solution: adjust a slightly narrower frequency range knowing that adjacent frequencies will adjust too
Recognize the impact reference microphone contamination has on programming
When amplified output escapes out of canal from large vents and open domes it
contaminates the reference microphones measurement of the input signal
Result: the reference microphone’s unit analyzer reduces the intensity of the
test signal and underestimates the device output
Solution: “stored equalization” calibration method
