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Amplification 2 > Real Ear Coupler Difference (RECD) > Flashcards

Real Ear Coupler Difference (RECD) Flashcards

1
Q

What is RECD?

A

A sound generating transducer produces a signal in the ear canal and in a 2cc coupler to measure the resonance of each.
RECD is the difference in decibels across frequencies, between an ear canal resonance and the resonance of the 2cc coupler

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2
Q

Why is RECD done?

A

Conversion from HL to SPL
Difference becomes conversion factor
Used to make coupler simulate the real ear
Can do the fitting and the measurements in the test box without the patient there
Mainly done for pediatrics

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3
Q

Is the RECD different patient to patient?

A

Yes

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4
Q

What are the two reasons for RECD measurement?

A

Accurately converts an individual’s HL audiometric thresholds, measured using inserts, to dB SPL values (creates personalized conversion values)
The prediction of real ear output when hearing aid measurements are made in the test box (used to preprogram device)

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5
Q

Why do you want to create personalized conversion values?

A

Allows you to create accurate fitting targets
Supplies precise adjustments for differences in canal volume and impedance variations

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6
Q

What is the ANSI standard coupler for RECD?

A

HA-1

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7
Q

What is the ANSI standard for RECD?

A

RECD measurement can be made with a custom earmold or EAR insert
The same coupler for BOTH measurements (either a foam tip and the HA-1 coupler or a custom mold and an HA-1 coupler)

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8
Q

Why is RECD gross?

A

Need to use funtak on every device (cannot be standardized)

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9
Q

What was done to make RECD less gross?

A

ANSI established standard conversion factors between HA-1 to HA-2 coupler to support use of the HA-2 coupler (don’t need funtak)

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10
Q

How is RECD measured?

A

Signal: Pink noise
The same acoustic signal must be used for BOTH measurements
The difference between these 2 resonances becomes a conversion factor
The conversion factor is added to 2cc coupler resonance to simulate the patient’s ear canal resonance in the 2cc coupler

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11
Q

What is the first step of RECD?

A

Measure the coupler response using RECD transducer
Navigate to “ON EAR” measures to RECD to “coupler calibration”

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12
Q

What is the second step of the RECD?

A

Measure the REUR first and then measure the canal resonance using a foam insert and the insert transducer
Use Aquaphor on the insert or earmold to reduce the slit leak

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13
Q

What does a negative LF value suggest in the RECD measurement (not the difference)?

A

Slit leak present
Negative LF results are expected when perfs or PE tubes are present (volume is larger)

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14
Q

How do you correct a slit leak?

A

Make sure you allowed the insert to fully expand
Increase the tip size
Apply Aquaphor to the foam tip to improve the seal

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15
Q

What does a negative RECD (>10 dB) in the 4-6 kHz region suggest?

A

Suggests the probe tube is blocked

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16
Q

What are the verifit 2 protocol differences for RECD?

A

Called WRECD (0.4cc coupler used to mimic the size of the ear canal)

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17
Q

What should you expect on the verifit 2 (WRECD)?

A

A negative LF responses on adult ears - a very large negative slope in the LF may still indicate the presence of a slit leak
Ear canal resonance above 1k Hz is equal to but not below the 0.4 cc coupler response
If it falls below the WRECD above 1 kHz it still indicates a blocked or pinched probe tube

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18
Q

When the RECD is above the dotted line, what does that mean?

A

The ear canal is smaller than normal

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19
Q

When the RECD is below the dotted line, what does that mean?

A

The ear canal is larger than normal

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20
Q

If you measure RECD with a vented mold, should you close the vent?

A

Yes, to stop the standing waves

21
Q

What is the practical benefit of personalizing conversion factors by using RECD?

A

Adjusts for the absolute volume as well as impedance differences in the canal
Smaller or larger than average canal volumes
Stiffer or more flexible than average
Perforations/ PE tubes
Fluid in middle ear space
Surgical distortion or scarring

22
Q

Is RECD a conformity evaluation?

A

Yes, as well as other real ear tests

23
Q

What will the RECD be like for a PE tubes and perfs?

A

Below 1.5k Hz, RECD will be up to 8 dB lower than the adult average
Indicates that the ear canal volume is larger than normal (LF energy escapes)
The SPL is affected more at low frequencies than at high frequencies (so easy for LF to pass through)
Perforation of the tympanic membrane may also reduce the amount of tympanic membrane vibration for a given SPL at the membrane
The combination of higher hearing thresholds and negative RECD values will result in more prescribed gain for average speech

24
Q

Should the RECD be remeasured when there is any change in ear status?

A

Yes

25
Q

Is RECD helpful with peds?

A

Yes, it is standard
RECD promotes additional gain required (important for fitting a child)
Accounts for need of gain that DSL is lacking
Because of RECD, don’t need to calculate ABG conversion

26
Q

How does open mastoid cavity affect the RECD?

A

It decreased the RECD in the mid and high frequencies

27
Q

How does ME effusion affect the RECD?

A

Increases the RECD in the mid frequencies
Stiffer system and smaller volume
If the middle ear effusion is longstanding, use the RECD values for hearing aid fitting
If it is a temporary condition, you may wait until the middle ear is healthy to measure RECD or use a previously measured RECD from when the ear was healthy for the hearing aid fitting

28
Q

What is the recommended protocol for RECD for adults?

A

Perform the RECD measurement during function and communication needs assessment
Print table of results for records (or document values)
Run ANSI measurements confirming device function
Use RECD data to preprogram device
Perform listening check (directional mics and manual program function)

29
Q

How do you preprogram a device in the test box?

A

Place the device in the test box
When using an earmold from programming, block a vent from the medial side of the mold
Enter the vent size when setting up acoustic parameters in the programming software
Select style and coupler

30
Q

How do you verify the audibility of the HF /s/?

A

Use the /s/ stimulus to assess HF audibility
Adjust frequency lowering, if needed (add the least amount of frequency lowering required to put the upper shoulder of the /s/ into the MAOF)

31
Q

During the appointment (with RECD), what do you need to do?

A

Run DFS
Perform speechmap only at 65 dB (to verify performance of vent and acoustic properties, and to verify audibility conforms to your expectations)
No need to complete REOR

32
Q

Can you use speechmap as a counseling tool?

A

Yes
It shows them the sounds that they can hear now

33
Q

What are conformity evaluations?

A

A conformity evaluation is a hearing aid check that is performed for the purpose of evaluating the performance of the hearing aid, evaluating the benefit that the hearing aid provides the patient, and to ensure that the hearing aid continues to meet the original prescription such that its settings have not changed somewhere in the interim

34
Q

What are other ways to verify best fit (conformity evaluations)?

A

On-Ear Real Ear Verification
RECD measurement and Test Box Programming
Aided functional gain (thresholds without and with hearing aids)
Aided speech intelligibility measures
Aided subjective ratings (subjective speech intelligibility judgments, speech quality judgments, and loudness rating)

35
Q

Why do we have to use alternative conformity methods for patients?

A

Cannot be used on CI or BAHA
Need to be aware of other methods of evaluation

36
Q

What are aided functional gain measurements?

A

Compares aided thresholds to unaided thresholds using puretone signals in the sound field
Patient position: 0º azimuth to soundfield speaker
Signal: pulse pure tone or warble signals
Masking is presented via headphone to opposite ear to assess one device at a time
Unaided SF thresholds obtained for key octaves (500 - 4k Hz to ensure accuracy of measurement)
Aided SF thresholds obtained for the same frequencies
The differences between the two represent the “functional gain (FG)” provided by the hearing aid

37
Q

Why do you perform aided functional gain measurements?

A

REM equipment is not available
Gooey cerumen clogs probe mic
Pediatric fittings or uncooperative patients
CI, BAHA, or Lyric fittings
Some federal government agencies require the test

38
Q

What is the ideal aided threshold?

A

The ideal aided threshold should at least allow the lowest intensity level of normal speech to be audible
Expected aided functional gain is often not achieved, especially at the high frequencies

39
Q

What are aided functional gain pitfalls?

A

Test-retest reliability is poor (could vary by 10-15 dB)
Test only identifies the threshold of audibility (pure tone goes down in intensity, the gain is increased; expansion attenuates soft sounds) (more easily done with linear devices)
Calculated aided function gain does not show gain for conversational level sounds
Ensuring WDRC successfully shaped the signal into a reduced dynamic range requires multi-intensity assessments (soft, moderate, loud)
Aided thresholds are invalid for near-normal thresholds (ambient noise masks the test signal)
Limited number of frequencies assessed
Device features could suppress audibility of tones (too fast for AT and RT, DFS can attenuate it)
Loss of HF aided functional gain in non-linear HA is caused by the AGC TK
Every time you modify gain, you need to do it again

40
Q

Is the aided threshold measure considered to be a conformity measure?

A

Yes
Some audiologists do it instead of real ear

41
Q

What are aided speech intelligibility measures?

A

Conformity eval
Speech is presented through calibrated soundfield
Presentation level is typically 50 to 60 dB HL (average conversational speech)
Calibrated sentences in quiet and noise provide the most useful information
Can demonstrate improved intelligibility
Can demonstrate the benefits of technology designed to improve understanding in noise
Can demonstrate continued limitations of hearing in noise and the benefits of speech reading

42
Q

What is the adaptive quickSIN?

A

Performed in soundfield at 50 dB HL (increase to soundfield MCL, if needed) (want to see if they are improving in average conversational speech)
Tracks 24-35 contain sentence lists with four-talker babble recorded on separate channels
The tester manually manipulated the 4-talker babble signal

43
Q

What is the clinical usefulness of the adaptive quickSIN?

A

Ensures SNR loss did not degrade with amplification
Functional verification of improved performance with directional or remote microphones

44
Q

What is the set up for the adaptive quickSIN?

A

Set up one mic at zero degrees azimuth and one at 180 (binaural testing)
When the speakers are at 45 degrees to the patient, you cannot perform binaural testing (angle them so one speaker is towards the front of them (45 degrees) and one towards the back (45 degrees)

45
Q

What is the audiometer set up for the adaptive quickSIN?

A

Calibrate both channels of CD
Target talker = Channel 1; 4-talker babble = Channel 2 (behind them)
Test signals- tracks 24 to 35
Presentation level: 50 dB HL (or 62dBSPL)

46
Q

How do you counsel with adaptive quickSIN?

A

Convert the percent of words correct for each of the six SNR ratios to compare aided to unaided (put it on a graph to see difference)
Discuss the most difficult listening situations noting this is also true for people with normal hearing
Point out that when the noise is soft, only minimal benefit will be present
Emphasize and describe those environments where listening is easy, to those which will be very hard

47
Q

What is the aided loudness rating?

A

Conformity eval
The patient is aided bilaterally, with the hearing aids programmed appropriately to validated targets
Provide the patient with the loudness anchors chart (1-7; same as LDL)
Deliver a 45 dB SPL continuous speech signal. An acceptable rating is a #1, #2, or #3
Deliver a 65 dB SPL continuous speech signal. An acceptable rating is #3, #4, or #5
Deliver an 85 dB SPL continuous speech signal. An acceptable rating is #5 or #6
Just comparing the scores to the scores that we should be getting

48
Q

What is the subjective speech intelligibility judgments?

A

Conformity eval
Fluff (not worth it)
Patient judges ‘ease of listening’ while listening to passages presented at 50 dB HL

49
Q

What is subjective speech quality judgments?

A

Conformity eval
Fluff
Patient judges sound quality while listening to passages presented at 50 dB HL

Amplification 2 (13 decks)

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