Outcome measures of hearing aid performance: verification and validation Flashcards

1
Q

Why do we need outcome measures?

A

To assess whether the patient is getting the best possible result from the hearing aid we have fitted

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2
Q

What kind of questions should be asked to the patient immediately after fitting the hearing aid?

A
  1. Is the aid comfortable in the ear?
  2. What do they think about the quality of sound (own voice, audiologist’s voice, other sounds?)
  3. Loudness of sound- is it what they expected? Too loud? Too quiet?
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3
Q

What kind of questions should be asked to the patient at the hearing aid review appointment?

A
  1. How long do they wear the aid every day?
  2. What do they think of the sound quality?
  3. Are there any particular problem situations?
  4. How does their own voice sound?
  5. Any problems with loud sounds?
  6. Any problems with acoustic feedback?
  7. Can they insert/ remove the mould?
  8. Is the aid comfortable to wear?
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4
Q

What are the two main reasons for measuring outcomes?

A
  1. Patient-oriented- assess patient’s needs, assess effectiveness of rehabilitation and need for further help
  2. Service-oriented- to evaluate service and change to service
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5
Q

What are the three main types of outcome measures in hearing aid assessment? What are some examples of each?

A
  1. Audibility: aided thresholds and speech tests
  2. Technical outcomes: real ear measurements (REMs)
  3. Self report questionnaires: hearing aid benefit, satisfaction with aids, satisfaction with services
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6
Q

What are aided thresholds?

A

-Aided vs unaided thresholds
-A measurement of functional gain
-Soundfield presentation e.g. warble tones/ narrow band noise

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7
Q

How do you calculate functional gain?

A

Functional gain= Unaided threshold- aided threshold

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8
Q

In what situation are aided thresholds particularly useful?

A

When REMs are impossible e.g. congenital atresia of external meatus

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9
Q

What is the advantage of using aided thresholds to measure hearing aid outcome?

A

May be useful to demonstrate to others (e.g. parent, significant other) that the HA is making a difference

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10
Q

What are the disadvantages of using aided thresholds to measure hearing aid outcome?

A

-Time-consuming to perform
-Results can be variable depending on patient concentration
-Does not measure dynamic aspects of HA performance e.g. wide dynamic range compression

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11
Q

How can speech tests be used to measure hearing aid outcome?

A

-Test the client’s hearing for speech when wearing the hearing aid
-Test prior to fitting for reliable results and repeat once the aids have been fitted
-Can also be used to ensure adequate speech development in hearing impaired children
-Can use live voice or recorded, in quiet or in noise, with or without visual information

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12
Q

Name two speech tests

A

AB word list and BKB sentences

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13
Q

What are the advantages of speech tests in measuring hearing aid outcomes?

A

-High “face validity”
-Can readily demonstrate difference between unaided and aided situation to patients/ others
-Some tests e.g. FAAF can identify particular speech sounds which are causing difficulty
- Auditory alone vs audiovisual can demonstrate the importance of visual cues to communication

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14
Q

What are the disadvantages of speech tests in measuring hearing aid outcomes?

A

-Cannot replicate real-life listening conditions easily in the clinic
-May be time consuming to do
-Results dependent on measurement conditions e.g. noise/ no noise, signal-to-noise ratio
-Unless many items are used, the % difference between conditions A and B has to be quite large for statistical significance

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15
Q

How can speech in noise testing be used to measure hearing aid outcomes?

A

-Test speech intelligibility in background noise
-Difficulties in background noise is one of the most common complaints for hearing impaired people even when wearing hearing aids
-These tests can demonstrate functional improvements following hearing aid fittings or changes to hearing aid settings

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16
Q

Name three examples of speech in noise tests

A

-Hearing in Noise Test (HINT)
-QuickSIN
-Bamford-Kowal-Bench SIN (BKB-SIN)

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17
Q

How can Real Ear Measurements (REMs) be used to measure hearing aid outcomes?

A

-Measures the hearing aid output in the ear canal of the wearer
-Small “probe tube” microphone is inserted into the ear canal
-A reference microphone is placed next to the pinna
-Sound stimuli are produced and the sound level within the canal is compared to the level at the reference mix
-Can be carried out with or without the hearing aid in place

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18
Q

What are the advantages of REMs?

A

-Produces an entire objective measure of what the aid is doing
-Little patient co-operation required
-Quick and easy to perform
-Gives information about the whole frequency range
-Can immediately demonstrate the effect of changes to the hearing aid settings
-Good test-retest repeatability

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19
Q

What are the disadvantages of REMs?

A

-They are only as good as the prescription formula used
-This can be a problem as prescription rule developments usually follow developments in technology- current formulas don’t take the latest technologies into account
-Audiologists can become too REMs driven and forget about the needs of the patient
-Cannot perform if excessive wax or infection are present
-Results can be affected by changes in the placement of the probe mic
-Can be difficult to perform on children as they have narrow ear canals and do not like to keep their heads still

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20
Q

What are the most commonly used questionnaires to assess hearing aid benefit in the NHS?

A

Glasgow Profules and Client Oriented Scale of Improvement (COSI)

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21
Q

What are the advantages of using questionnaires to measure hearing aid benefit?

A

-Allow comparisons before and after fitting and to normative data
-Enable services to gather data about the local population in terms of both the hearing loss and hearing AI

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22
Q

What are the disadvantages of using questionnaires to measure hearing aid benefit?

A

-Measure different things- not comparable
-Can be time consuming
-The patient may not be able to complete the questionnaire if they do not understand the questions

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23
Q

What is the real ear unaided response?

A

-The sound level recorded in the open ear canal plotted on a graph across the frequencies
-Hearing aid is not inserted in the ear

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24
Q

Where should there be a REUR resonant peak in an adult?

A

At approximately 2.7 kHz but it differs in all individuals

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25
Q

What is the real ear occluded response (REOR)

A

-The sound level recorded in the ear canal when the hearing aid is inserted in the ear
-Resonant peak may be ‘lost’ because the earmould or aid stops the ear canal from resonating

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26
Q

What kind of fit is it when the REUR and REOR are similar?

A

Open fit

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27
Q

What is the real ear aided response (REAR)?

A

-The sound level in the ear canal across frequencies of sound with the hearing aid in the ear and turned on
-Used to compare hearing aid output to prescription targets

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28
Q

What is the real ear insertion response (REIR)?

A

The difference (in dB) between the sound levels measured in the ear with hearing aid in and on and without the hearing aid in the ear

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29
Q

How is the REIR calculated?

A

-REAR-REUR= REIR
-Area between blue line (REUR) and red line (REAR) is the REIR

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30
Q

What is the real ear saturation response (RESR)?

A

-The maximum sound pressure level the aid is capable of delivering in the client’s ear, across the frequencies, measured with the aid in saturation
-This is an extremely loud stimulus level so is not used routinely in clinical testing

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31
Q

What is the purpose of measuring the REUR?

A

To establish the baseline sound level in the ear

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32
Q

What is the purpose of measuring the REOR?

A

To identify whether we have an open or occluded fit so we can select the correct method of calibration for the equipment

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33
Q

What is the purpose of measuring the REAR?

A

To identify whether the hearing aid meets prescription fitting targets

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34
Q

Why do we need to calibrate the probe tube?

A

-The probe tube and microphone don’t have a flat frequency response
-The probe tube is changed regularly so different tubes will affect the real ear measurements we make
-We need to correct for this by making the probe tube “invisible”
-Probe calibration resets the internal equipment settings to eliminate the acoustical effects of the probe tube
-The REM equipment measures probe microphone (PM)- reference microphone (RM) during calibration

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35
Q

When should the probe tube calibration be performed?

A

-At the start of REMs
-Whenever the probe tube is changed during REMs

36
Q

What measurement is this graph showing? Which ear(s) have been recorded?

A

-The real ear unaided response (REUR) from the right ear
-There is a resonant peak at 3 kHz which is due to ear canal resonance
-The REUR has not been recorded for the left ear

37
Q

What measurement is this graph showing? Which ear(s) have been recorded? What kind of fitting would this be? What method of REMs equalisation would be used here?

A

-The real ear occluded gain (REOR) from the right ear
-The black line is the REUR and the red line is the REOR
-The REUR and REOR are similar which means the hearing aid is an open fitting
-MPMSE should be used when recording the REAR
-The left ear has not been tested

38
Q

Label the components of the real ear aided (REAR) response graph

A
  1. The REAR is measured in dB SPL
  2. Amplified Average Speech Line: the solid orange curve is the amplified average speech line
  3. Prescription targets: the dotted orange line is the prescription target
  4. Amplified Speech Spectrum: shaded orange area indicates the amplified speech spectrum
  5. Hearing thresholds: circles indicate the hearing thresholds
  6. Non test ear: The left ear has not been tested
  7. Test parameters: this REAR was recorded with a 65 dB ISTS (speech) test signal and is being compared to NAL-NL2 prescription targets
39
Q

Where should the amplified speech spectrum lie?

A

Above the hearing thresholds but below the ULLs (or predicted ULLs) to ensure the sound fits into the wearer’s dynamic range

40
Q

What measurement is this graph showing? Which ear(s) have been recorded? What kind of fitting would this be? What method of REMs equalisation would be used here?

A

-Real Ear Occluded Gain (REOR)
-The right ear has been recorded
-The black line is the REUR and the red line is the REOG
-This is a closed fitting as the earpiece blocks off the ear canal and reduces the sound level in the ear when compared to the REUR
-MPMCE should be used as the method of REMs equalisation

41
Q

What is the tolerance value for close the response curves should be to the prescription target?

A

+/- 5 dB

42
Q

How long should the recording be run for to acquire a stable and repeatable Long Term Average Speech Spectrum (LTASS)?

A

10 seconds

43
Q

What is the distance at which the tip of the probe tube should be positioned away from the tympanic membrane?

A

The tip should be within 5mm of the tympanic membrane

44
Q

What is the probe tube lengths for men and women?

A

28mm for adult females and 30mm for adult males

45
Q

What is the real ear to coupler difference (RECD)?

A

-A measurement of the difference (in dB) between the response to a signal in the patient’s ear and the same signal in a 2cc coupler as a function of the frequency
-Essentially how much the patient’s ear differs from a 2cc coupler

46
Q

What is used to measure real ear to coupler differences (RECD)?

A

Insert earphones and foam tips or custom earmoulds

47
Q

How are RECDs measured?

A
  1. SPL probe is used to deliver sound to the 2cc coupler in the test box
  2. Measure the ear response by setting up for a REM and attaching the SPL to the earmould tubing to deliver the sound
  3. The system deducts the coupler response from the ear response to identify the real ear to coupler difference
48
Q

What can we do with the RECD measurement?

A

-We can use it as a correction factor to convert coupler dB SPL for sound through the hearing aid to dB SPL at the eardrum
-We can then try a variety of hearing aids or hearing aid settings to establish which is the best match to target outputs (or insertion gain) without the patient present

49
Q

How does age affect the RECD?

A

The RECD changes with age as the shape and acoustic resonance of the ear canal alters

50
Q

What are the benefits of the RECD?

A
  1. Quick to perform
  2. Allows hearing aid to be set up and adjusted in the test box
  3. Can evaluate and compare different hearing aids without the patient having to be present
  4. Can be used when REMs is difficult e.g. children or patients with continuous outer ear infections
51
Q

Define impairment

A

Loss or abnormality of psychological, physiological or anatomical structure or function e.g. hearing loss

52
Q

Define disability

A

Any restriction or lack of ability to perform an activity e.g. ability to understand speech

53
Q

Define handicap

A

A disadvantage that prevents the fulfilment of a role that is considered normal for that individual e.g. withdrawal from an activity

54
Q

What are the two Glasgow profiles and what are they used for?

A
  1. The Glasgow Hearing Aid Benefit Profile (GHABP): designed to assess the benefits of fitting a hearing aid to a new hearing aid user
  2. Glasgow Hearing Aid Difference Profule (GHADP): designed to assess the benefits of changing hearing aids or hearing aid settings for existing hearing aid users
55
Q

What does part 1 of the Glasgow Hearing Aid Benefit Profile consist of?

A

-Part 1 is applied before the hearing aid is fitted
-The client is asked whether they have difficulty hearing in a particular listening situation
-They are then asked to rate the level of difficulty they experience and how much embarrassment they experience
-The patient can then add up to 4 additional listening situations that they personally find difficult

56
Q

What does part 2 of the Glasgow Hearing Aid Benefit Profile consist of?

A

-Patient is asked about the listening situations identified in part 1 plus up to 4 additional situations specified by the patient
-They are asked what proportion of the time they wear their hearing aids in the situations, how much their hearing aids help them in the situation, how much difficulty they now have in this situation and how satisfied they are with their hearing aids

57
Q

What are the 6 dimensions measured by the GHABP?

A

-Before aid is fitted: initial disability, handicap
-After aid has been worn for some time: hearing aid use, benefit, residual disability, satisfaction

58
Q

What are the two ways that the GHABP scores can be compared?

A
  1. With subject (e.g. before and after fitting a hearing aid or making a change to the settings)
  2. With national or local populations
59
Q

Describe these results from the GHABP

A

-Results show reduced disability
-Improvements in disability
-Low levels of handicap
-High levels of use
-Reasonable benefit and satisfaction

60
Q

Describe these results from the GHABP

A

-Low hearing aid use
-No improvement in disability
-Moderate handicap, satisfaction and benefit
-Further counselling regarding use of aid may be helpful

61
Q

Describe these results from the GHABP

A

-Improved disability
-Moderate handicap, benefit and levels of use
-Investigate reasons

62
Q

What does part 1 of the client oriented scale of improvement (COSI) consist of?

A

-Patient is asked to identify up to 5 listening situations where they would like to hear better
-The situations are recorded on the form in as much detail as possible and then rated on their importance (1= most important)
-Each situation can be further categorised into one of 16 “listening categories”

63
Q

What does part 2 of the client oriented scale of improvement (COSI) consist of?

A

-For each previously identified listening situation, the patient is asked to:
1. Rate the amount of improvement following hearing aid fitting
2. Rate their final ability to hear with the hearing aids in that situation

64
Q

What results does the COSI provide?

A

Qualitative measurement of changes in perceived disability for specific, user defined and user prioritised listening situations and final communication ability

65
Q

What are the advantages and disadvantages of the GHABP?

A

Advantages: Measures a greater number of variations with which to monitor benefit from the hearing aid
Disadvantages: Can be time-consuming, some clients find it difficult to use the rating scales used

66
Q

What are the advantages and disadvantages of the COSI?

A

Advantages: Very patient oriented, easy and fairly quick to perform
Disadvantages: Measures fewer variables and therefore provides less information

67
Q

What are fixed SNR tests?

A

-Fixed signal-to-noise ratio (SNR) tests measure a percent correct at a fixed SNR
-SNR conditions are established by the clinician prior to the test

68
Q

What is the advantage of fixed SNR tests?

A

They provide a straightforword percent-correct score for hearing aid benefit that is easy to explain to patients

69
Q

What is the disadvantage of fixed SNR tests?

A

It is difficult to know where to fix the SNR, as if the test is very challenging the results may understate the amount of benefit the hearing aids are providing the patient whereas if it is too easy the aided benefit may be overstated

70
Q

What are the clinical applications of fixed SNR tests?

A
  1. Present three lists in the unaided condition at three SNR levels (-1 dB SNR, +2 dB SNR, +6 dB SNR)
  2. Present the fixed SNR tests in the sound field with the speech and noise both presented from the same loudspeaker
  3. Once you obtain the unaided scores in each listening condition, repeat the test in the aided condition
  4. Compare the aided and unaided scores
  5. Explain to patient the differences between the aided and unaided scores
  6. Compare the patient’s results with those of someone with normal hearing to create realistic expectations
71
Q

What is the connected speech test (CST)?

A

-Passages of speech 9-10 sentences in length presented with multi-talker babble
-The score is based on the percent correct of 25 key words in each passage

72
Q

What is the speech perception in noise test (SPIN)?

A

-Consists of sentences between 5-8 words long presented with multi-talker babble
-The last word of each sentence is the one scored
-Half of the test items have high predictability and the other half low predictability
-The test is scored as a percent correct with separate scores for the high and low (minimal contextual cues) speech and noise presented from same loudspeaker

73
Q

What are adaptive SNR tests?

A

-Measure speech-to-noise ratio as the intensity level of either the speech or the noise is varied
-Can be conducted with earphones

74
Q

What is the HINT?

A

-Modified BKB sentences delivered in groups of 10
-Speech-shaped noise is the competing background noise
-Requires the background noise to be fixed at 65 dB SPL while the presentation level of the sentences varies in 2dB steps
-The reception threshold for sentences (RTS) is calculated like an SRT
-The RTS score is the signal-to-noise ratio at which 50% of the words are repeated correctly

75
Q

What is the QuickSIN?

A

-Series of IEEE sentences presented in a background of four-talker babble
-Sentences are presented at 75 or 80 dB HL while the CD automatically varies the SNR in 5 dB steps starting at +25 SNR
-5 key words are scored in each sentence and one point is given for each key word repeated correctly
-The SNR loss is calculated by subtracting the number of key words correct from 25.5 dB (reference)

76
Q

What are the clinical applications of adaptive SNR tests?

A
  1. Diagnosing SNR loss: measure of how well a patient understands speech in noise relative to someone who hears normally in noise and is not reflected in the pure-tone audiogram
  2. Aided audibility in noise: effective way of demonstrating to the patient that aided performance is better than unaided for noisy conditions
  3. Assessing directional microphone benefit: with two speakers mounted in strategic locations, speech in noise tests can verify that directional microphone hearing aids are functioning as intended
77
Q

Describe the International outcomes inventory for hearing aids (IOIHA) questionnaire

A

-Short number of questions
-Looking at the change that has been created in terms of quality of life

78
Q

What are the advantages and disadvantages of the IOI HA questionnaire?

A

Advantages: good structure, patient completes in their own time (good use of clinical time), provides data that is easy to combine across patient groups
Disadvantages: not as comprehensive as the COSI o the GHABP

79
Q

How are IOI HA results interpreted?

A

-Use the patient responses to begin discussions
-Can look at HA usage, problems causing negative perceptions of benefit
-Can identify possible solutions to address these issues
-Discuss options with the patient and alter hearing aid settings accordingly

80
Q

How can this COSI questionnaire be improved?

A

-Situations need to be more specific
-The categories are missing
-Some of the situations require expectation management

81
Q

What was the COSI designed to specifically improve?

A

Communication needs

82
Q

Interpret these COSI results

A

-Not getting benefit in all listening situations but getting some benefit
-Need to manage expectations or change the settings of the hearing aids
-Need to make sure they are getting as much benefit as possible in the situation with the highest priority
-Need to think of additional programs which may be useful such as a loop system, directional microphones

83
Q

Interpret these COSI results

A

-Getting benefit in all situations but not as good as they would like them to be
-Improving the settings might help all the areas as we may be slightly under target
-Might want to consider noise reduction settings, loop program, wireless streaming

84
Q

Interpret these GHABP results

A

-Disability and handicap are consistent with each other
-Not using their hearing aids are much as you would expect
-However they are getting some benefit from them
-Initial and residual disability roughly the same
-Not wearing the aid enough to acclimatise
-Satisfaction seems to be okay- are they really happy with something they are not wearing very often?

85
Q

Interpret these GHABP results

A

-Initial disability less than you would expect, handicap a little more than you would expect
-Usage is okay but could be better
-Getting reasonable benefit
-However satisfaction is very low despite wearing the hearing aid for a reasonable amount of time
-Need to establish why they are not happy

86
Q

Who can you not use speech in noise tests on?

A

-People with limited or no English language
-People with dementia, reduced cognitive function or intellectual disabilities
-People who have been unable to cooperate fully during other hearing assessment or who produce unreliable results
-Occlusion of ear canals which cannot be removed prior to testing