Post on 21-Sep-2020
Presenter:
John Pumford, Au.D., FAAA, AUD(C)
Director of Audiology and Education
Audioscan
[Photo of
Presenter]
MODERN HEARING AID VERIFICATION:
TOOLS AND TECHNIQUES FOR DELIVERING
IMPROVED PATIENT OUTCOMES
LEARNING OBJECTIVES
Use real-ear measurements (REM) more confidently in a
greater number of fitting conditions
Interpret verification findings with greater understanding
and accuracy
Solve a larger number of hearing aid fitting and
verification challenges more effectively
WHY VERIFY?
Benefits of Real-Ear Measurement
REM HAS BEEN ASSOCIATED WITH…
Improved audibility
Improved listening outcomes
Improved fitting efficiency (reduce fitting visits)
Improved patient satisfaction
Improved patient loyalty
Improved perceived quality of services
“VERIFY ACOUSTIC CHARACTERISTICS
USING PROBE MICROPHONE
MEASUREMENTS.”
INTERNATIONAL HEARING SOCIETY, BEST PRACTICES RECOMMENDATION
FOR FITTING AND DISPENSING HEARING AIDS (2019)
ARE WE CONDUCTING REM?
Surveys indicate REM not routinely done
Mueller & Strouse (1995): 39% (n=134 AuDs; n=108 HIS)
Mueller (1999): 42% combined use for those with equipment
Mueller (2003): 37% (n=558 AuDs; n=49 HIS)
Mueller (2005): 34% overall use rate w/AuDs
Mueller & Picou (2010): 42% overall use rate (n =309 AuDs; n=111
HIS)
Mueller (2014): Estimated 30% overall use rate
SOME REASONS FOR NOT USING REMS…
“The fitting software will set it right, shows me what I
need”
“Can’t be used with proprietary fitting methods”
“Patients don’t like it at target”
“Too time consuming”
“Too difficult”
“Too expensive”
“Doesn’t make a difference” [to my patients or my
practice]
CAN WE RELY ON THE FITTING SOFTWARE?
NAL-NL2 REAR Results Using 5 Different
Manufacturers’ Programming Software
Sanders, J., Stoody, T., Weber, J., Mueller, H., “Manufacturers’ NAL-NL2 Fittings Fail
Real Ear Verification” Hearing Review, March 2015; 21(3): 24-32
N = 16
55dB
Fitting software showed match within 1 dB!
65dB 75dB
NAL-NL2 COMPARISON TO 5 DIFFERENT
MANUFACTURERS’ PROPRIETARY FITTINGS
N = 16
55dB 65dB 75dB
Sanders, J., Stoody, T., Weber, J., Mueller, H., “Manufacturers’ NAL-NL2 Fittings Fail
Real Ear Verification” Hearing Review, March 2015; 21(3): 24-32
TAKEAWAYS
Selecting a fitting formula in software does not
guarantee targeted performance (or audibility)
Proprietary fitting formulas tend to underamplify vs.
validated generic fitting formula
The only way to KNOW what you are delivering to the
eardrum is through verification measures
IMPORTANCE OF ‘VERIFIED’ AUDIBILITY
Leavitt R., & Flexer, C. (2012). The importance of audibility in successful amplification of hearing loss. H Review, 19(13), 20-23.
From Mueller, H.G. (2014, January). 20Q: Real-ear probe-microphone measures - 30 years of progress? AudiologyOnline,
Manufacturer’s Formula
Fitted to NAL-R
SNR
Loss
(dB)
N = 5
IMPORTANCE OF VERIFIED AUDIBILITY – REAL WORLD
Abrams et al. (2012). Initial-fit approach versus verified prescription: comparing self-perceived hearing aid benefit. Journal of
the American Academy of Audiology. 23(10), 768-778.
N = 22
15 of 22 (~70%) preferred the verified NAL fitting
TAKEAWAYS
Hearing improvement requires more than just a ‘product’
Manner in which the product is fitted can greatly influence
benefit
Verified fit to validated targets (via professional care) can
significantly improve outcomes
GETTING STARTED
Laying the groundwork for REM
PROBE TUBE PLACEMENT CONSIDERATIONS
Location near the eardrum required
for accuracy (~5mm)
Minimizes contamination of ‘standing
waves’
Challenging
Too deep = patient discomfort
Too shallow = measurement error
12mm
12mm
5mm
5mm
PROBE TUBE PLACEMENT METHODS
Visually-assisted positioning
Use anatomy of external ear to
guide positioning
Insert probe tube until marker
approaches inter-tragal notch
Check position with otoscopy
PROBE TUBE POSITIONING
TIP: can use probe module body!
28mm
28mm
PROBE TUBE PLACEMENT METHODS
Geometrical positioning
Use ridge of earmold / hearing aid
Extend 3-5 mm beyond tip of mold
AUDIOSCAN PROBE GUIDE (PG)
Uses standing waves in ear canal to
determine probe tube location &
guide placement
Developed using machine learning
modeling and a large acoustic data
set with adult ear canals
Real-time measures compared to
acoustic model to indicate when
probe tube is within 5 mm of TM
THINGS TO CONSIDER
Developed and validated with adults w/normal outer &
middle ear function
Future studies to expand modeling data and evaluate
performance with other patient populations
Does not eliminate need for best practice procedures
with probe tube placement, particularly otoscopy
TIPS FOR REAL-EAR SETUP:
PROBE MODULE POSITIONING
TIPS FOR REAL-EAR SETUP:
CABLE ADJUSTMENT
X
TIPS FOR REAL-EAR SETUP:
PROBE TUBE INSERTION
2) Use otoscopy to check the
depth of probe tube.
1) Guide tube until mark
meets intertragal notch.
TIPS FOR REAL-EAR SETUP:
PROBE TUBE INSERTION
TIPS FOR REAL-EAR SETUP:
FOAM TIP, HEARING AID INSERTION
4) Ensure a good seal (use lubricant; let foam expand)
3) Insert earpiece(foam tip, earmold, hearing
aid)
You are ready to measure the real ear response!
REM POSITIONING CONSIDERATIONS
Locate away from reflective surfaces (~1.5 m)
Seat patient 0.5 – 1m from speaker
Balances environmental influence & patient comfort
Recommended azimuth can vary by manufacturer
0˚ or 45 ˚ typically recommended
SPEECHMAP®
The Core Verification Resource
ACCESS THE SPEECHMAP SCREEN
AUDIOMETRIC DATA ENTRY
1. Choose target
formula
2. Select age
3. Choose
audiometric
transducer
AUDIOMETRIC DATA ENTRY
4. Select RECD average,
enter, or measure
5. Select RECD Coupling
6. Select monaural or
binaural fitting
7. Select tonal or non-
tonal language (NAL-
NL2)
HL AUDIOGRAM ENTRY
THE BASIC SPEECHMAP SCREEN
SPEECHMAP AS AN INITIAL
COUNSELING TOOL
THE BASIC SPEECHMAP SCREEN
VERIFYING DEVICES USING
SPEECHMAP
FITTING TEST ONE: SOFT SPEECH
36 42
FITTING TEST TWO: AVERAGE SPEECH
FITTING TEST THREE: MPO
FINAL FITTING SUMMARY
TOOLS TO EVALUATE THE
FITTING
SII TARGET RANGES
Upper & lower limits shown in Audibars
DSL Child and Adult
Lower limit Upper limit
RMS ERROR TO TARGET
RMS ERROR TO TARGET
McCreery RW, Bentler RA, Roush PA. The Characteristics of Hearing Aid Fittings in Infants and Young Children. Ear and
Hearing. 2013:34(6):10.
BINAURAL MONITOR HEADPHONES
Listen to test-box or real ear tests.
Evaluate hearing aid function binaurally—for
easy troubleshooting.
PRE-FITTING IN THE TEST
BOX
RECD APPLICATIONS
Convert test box measures of hearing aid to estimated
real-ear aided response (S-REM)
Convert audiometry (e.g., threshold and UCL) with insert
phones from dB HL to dB SPL
RECD MEASUREMENT: HOW IS IT
DONE?
Composed of 2 measurements:
1. Coupler measurement (Transducer calibration)
2. Real-ear measurement
HOW DO WE MEASURE RECD?
1. Measure coupler
response
Verifit VF-1, Axiom, RM500SL
Verifit 2
HOW DO WE MEASURE RECD?
2. Measure Real Ear
Response
IDEAL END RESULT
Est.
Eardrum
SPL
+
Hearing aid
INPUT
Hearing aid
OUTPUT
COUPLER
RECD+ MLE
SIMULATED REM IN TEST BOX
OPEN FITTINGS
Verification Considerations
WHAT IS AN “OPEN” INSTRUMENT
“Open” NOT defined by hearing aid design
Thin Tube
RIC
“Open” defined by hearing aid coupling
If coupling does not occlude ear, it is an “Open” fitting
ONE METHOD FOR DETERMINING “OPEN” FIT
Record 65dB Speech (Test 1) with only probe tube in ear
(REUR)
Repeat 65dB Speech (Test 2) with aid in ear, but muted
(REOR)
If two results are essentially the same, it is an “Open”
fitting
OCCLUSION EFFECT TESTING
OCCLUSION EFFECT TESTING
Open Dome Closed Dome Power Dome
IF AN OPEN FITTING IS PRESENT
Consideration #1: Pre-fitting in coupler
All fitting measures should be done on
the ear
Accurately modeling on-ear venting with
coupler not currently possible
IF AN OPEN FITTING IS PRESENT
Consideration #2: Sound field calibration
Hearing aid outflow from ear canal
received by reference microphone
Lowers loudspeaker signal level
Lower input = lower measured output
IF AN OPEN FITTING IS PRESENT
Consideration #2: Sound field
calibration
Use ‘stored’ equalization (Disables ref
mic)
Outflow will not impact speaker level
If you cannot disable ref mic, move it
away from ear canal
EFFECT OF EQUALIZATION APPROACH
Mueller, H.G., Ricketts, T.A., “Open Canal Fittings” Ten Take Home Tips”, Hearing Journal, v9:11, Nov. 2006
AN OPEN-FIT SPEECHMAP PROTOCOL
Place probe tube / hearing aid as usual
Select “Open” in Instrument menu
Turn OFF (or Mute) hearing aid
Click on test signal and store
‘equalization’ when prompted
Turn ON hearing aid
Conduct Speechmap per typical
Test 1 (55dB) soft speech
Test 2 (65dB) average speech
Test 3 (75dB) loud speech
Test 4 (MPO)
ADVANCED FEATURE
VERIFICATION
Directional Microphone Testing
DIRECTIONAL TESTING (TEST BOX)
Rear speakerFront speaker
DIRECTIONAL IN TEST-BOX - BTE
Rear speakerFront speaker
DIRECTIONAL IN TEST-BOX - ITE
DIRECTIONAL TESTING (REM)
Rear speaker
Equal distance
Aided ear with
probe tube positioned
DIRECTIONAL TESTING
Omni (i.e. directional off)
Thick line represents front speaker.
Thin line
represents right
or left rear
speaker.
Curve separation indicates
directional function
DIRECTIONAL TESTING
DEMO
Directional Mic Test In Test Box
ADVANCED FEATURE
VERIFICATION
Noise Reduction Testing
NOISE REDUCTION PROPERTIES
Digital algorithm recognizes “non-speech” elements of
incoming signal Analyzes incoming signal modulation
Operates independently in bands
Performance varies greatly across manufacturers
No standardization in programming terminology
NOISE REDUCTION SIGNAL OPTIONS
NOISE REDUCTION TEST RESULT
Peak RMS Reference Curve
Noise Reduction Settled Curve
Peak RMS Reference Curve
Noise Reduction Settled Curve
DEMO
Noise Reduction Test In Test Box
ADDRESSING PATIENT ISSUES
AND TROUBLESHOOTING
CASE #1
67 y.o. male
First-time hearing instrument
wearer
Mild-moderate sloping S/N
hearing loss
Complaint:
“My own voice sounds boomy,
unnatural.”
SOME THINGS TO CHECK
Occlusion, Inadequate Venting
Occlusion Effect Test
Excessive LF Amplification
Speechmap Audibility
Listening Check with Monitor
Headset
‘Speech-Live’ while patient vocalizes
CASE #2
45 y.o. female
Experienced hearing instrument
wearer
Moderate high frequency S/N
hearing loss
Complaint:
“There is a tinny quality to sound.”
SOME THINGS TO CHECK
Probe tube placement
Not deep enough, programmed more HF
gain than needed
Remove, check, reinsert
Sound field calibration
Input may be too low (concurrent cal.),
programmed more HF gain than needed
Set venting to ‘Open’ in Speechmap
Excessive HF Amplification
Speechmap Audibility
CASE #3
70 y.o. male
First-time hearing instrument
wearer
Moderate-to-severe sloping S/N
hearing loss
Complaint:
“Still having trouble in noise.”
SOME THINGS TO CHECK
Insufficient amplification
Speechmap Audibility
Directional microphone test
Check for performance changes
Noise reduction test
INTERESTED IN LEARNING
MORE?
SUMMARY
Research and professional guidelines support the value
of REM
Reviewed procedural considerations to improve
accuracy of results and conclusions
Reviewed verification tools that evaluate device
performance, address patient complaints and inform
counseling
Verification highlights clinician value in addressing
hearing healthcare needs
QUESTIONS?