Probe Microphone Measurements - International Hearing Societyihsinfo.org › IhsV2 ›...

Probe Microphone Measurements

Presenter:

Wendy Switalski, AuD, MBA

Audiology Development Manager

Audiology Systems, Inc.

Enhancing Fitting Quality using PMM

www.audiologysystems.com


• 2 Groups: Above-Average Success Below-Average Success

• Examined ‘fitting protocol’ used (as reported by patient**)

• Significant differences found in components


Why is it important?

• Repurchase HA Brand: 81% vs. 14%

• Recommend HHP: 94% vs. 39%

• Would recommend HA: 97% vs. 56%

• Satisfaction with benefit: 99% vs. 12%

• HA in drawer: 3% vs. 18%


‘Successful’ patients reported receiving the following :

1. OBJECTIVE BENEFIT Assessment (+26%)

2. SUBJECTIVE BENEFIT Assessment (+25%)

3. LOUDNESS DISCOMFORT Measure (+24%)

4. REAL-EAR MEASUREMENT (+20%)

5. PATIENT SATISFACTION Measurement (+17%)


• High correlation between patient success and number of visits

• 76% with above-average success fit in 1-2 visits

• 47% with below-average success fit in 5-6 visits…versus 7% of the above-average group

• So clinical expertise, diligence and attention are not enough…


• Use Patient Reports/Acceptance of Sound Quality as goal

• Manufacturer’s Algorithm(s) determines initial settings

• Patient’s subjective opinions are used for gain and sound quality fine tuning

FITTING A: Manufacturer’s First Fit


Source: H. Aazh and B. Moore, Journal of the American Academy of Audiology; 18:653–664 (2007)

9

M1 M2 M3 M4

64% of “first-fit” hearing aids did NOT come within +/- 10 dB of NAL-NL1 target at 1 or more frequencies

FITTING A: Manufacturer’s First Fit


• Patient performance reports

• Significant other performance reports

• Lack of compliants

• Patient decision to continue use of hearing aids

FITTING A: Quality Markers


• Use Dynamic Range as Goal

• Verify using Live Speech

• Measurements made with Speech Peaks

FITTING B: First Fit with Verification


FITTING B: First Fit with Verification

Quality Markers:

• Examine output for varying input levels

• Check for unusual peaks

• Verify loud inputs do not exceed LDL’s


• Use Prescriptive Target as goal

• Verify using Recorded Speech-Like Stimuli

• Measurements made with LTASS and/or Speech Envelope (Percentiles)

FITTING C: Prescriptive Target Fitting


Quality Markers:

• Fit To Target

• Speech Intelligibility Index (SII)

• In-Depth analysis of Dynamic Range utilization

FITTING C: Prescriptive Target Fitting


Evaluate Openness of Fit


• Step One: Place Probe Tubes


PtP Short.wmv


• Step Two: Unaided Response

• Measure resonance of patient’s ear canals

• Expect ‘natural gain’ of ~ 12-15 dB in area of 2700 Hz

• Historically was used for Insertion Gain techniques…but has a ‘new use’



• Step Three: Occluded Response

• Place hearing instruments in ears, holding probe tubes to maintain placement

• Place in MUTE or OFF position



Is my Open Open? Yes


• When this is good: If you have planned for a truly open fitting for a client with normal low-frequency thresholds.

• When this is not good: If your amplification goals require low frequency gain or greater power than can be easily offered in the open configuration, this result suggests the need to change to a larger or more occluding "power" dome or consider a custom mold.

Is my Open Open? Yes


Is my Open Open? No


• When this is good: For fittings that require more power, this minimizes the opportunity for feedback occurrences, and simultaneously maximizes available gain. • The most effective "feedback management" encompasses both physical

fitting characteristics (optimized dome/ear canal match) in addition to digital instrument capabilities.

• When this is not good: This finding may be problematic when you have recommended an open fitting for a client with narrow ear canals, and you started with the smallest dome available.

Is my Open Open? No


• In a fitting that shows any level of occlusion, changing to a truly open configuration by selecting a smaller or more vented dome (if not contra-indicated by power needs) can have a dramatic and sudden positive effect.

• Conversely, in a fitting that is confirmed to be open, own-voice issues may require minor frequency response adjustments in the hearing instruments and/or counseling of the client.

• Remember…1-2 visits!

Why does it Matter? Occlusion v. Ampclusion


• Informs you whether to use ‘standard’ calibration procedures or OpenREM calibration. If the measurements reveal complete occlusion there is no need to use OpenREM calibration.

Why does it Matter? Calibration Choice


• Standard calibration = calibration tone occurs prior to each and every stimuli presentation and reference mic stays active during process

• OpenREM Calibration = stored equalization measured once with HI in place and muted or off; and then eference mic disabled. Remeasure if conditions change (i.e. patient moves).

Why does it Matter? Calibration Choice


• Defines the gain recommended across the frequency spectrum, based on hearing levels and other considerations.

• Primary Options: DSL v5.0; NAL-NL2.

• Both of which are evidence based with a host of literature validating them as tools for best practice

Prescriptive Fitting – The Basics


Prescriptive Fitting – The Basics

• Uses speech or speech-like signals as stimulus of choice

• Provides different targets for soft, average, and loud inputs

• Provides a consistent fitting approach regardless of make, model, manufacturer of device


• PREMISE: Loudness EQUALIZATION

• Aims to equalize perception of loudness over a range of frequencies instead of having low frequencies dominate loudness

• maximizing predicted speech intelligibility while constraining loudness

• EVOLUTION:

• From LINEAR approach to COMPRESSION approach.

• From INSERTION-GAIN (tones) to include AIDED Gain (speech) targets

• VALIDATION/EVIDENCE: modifications from NAL-NL1 included patient preference/comfort findings

NAL-NL2

Johnson, E. and Dillon, H., 2011


NAL-NL2 Fitting Details


NAL-NL2 Target example


NAL NL-2 Targets for Various Stimuli


• PREMISE: Loudness NORMALIZATION – Aims to restore, at each frequency loudness perception of the hearing

impaired listener to that of a normal hearing listener – Goals of avoiding loudness discomfort, providing audibility of speech

across a wide range of input levels, and accommodating the prescriptive targets for both quiet and noisy environments, as well as for infants versus children versus adults

• EVOLUTION: – **From pediatric-focus (earlier versions) to both pediatric and adult

versions.** – Modifications for ‘noise programs’ made – Correlates with data on Preferred Listening Levels (PLL)

Desired Sensation Level Multistage Input/Output (DSL m[i/o])- DSL v5.0

Johnson, E. and Dillon, H., 2011


DSL v5 Target Example


DSL v5 Targets for Various Stimuli

Tones vs Speech


DSL v5 Fitting Details


What they share in common…

• Evidence based prescriptions with a host of literature validating them as tools for best practice

• Use speech-like signals as stimulus of choice

• Differing targets for soft, average, and loud inputs

• Provide a consistent fitting approach regardless of make, model, manufacturer of device


NAL2 vs DSLv5- Where are they now? Soft (55dB) input

Purple = DSL5 (Adult) Orange = NAL-NL2 (Adult)


NAL2 vs DSLv5- Where are they now? Average (65) input

Blue = DSL5 (Adult) Green = NAL-NL2 (Adult)


Another Word About Prescription Targets

• Remember, a proprietary hearing aid manufacturer’s algorithm is NOT necessarily the same thing as NAL or DSL (and note that their proprietary method may be the default fitting formula)

• If you fit with formula ABC don’t expect it to match DSL on NAL…but you can use it as a starting point to get to a prescriptive target match


What You See on the Manufacturers’ Screen May Not Be What’s Happening In the Ear

Source: H. Aazh and B. Moore, Journal of the American Academy of Audiology; 18:653–664 (2007)

40

M1 M2 M3 M4

64% of “first-fit” hearing aids did NOT come within +/- 10 dB of NAL-NL1 target at 1 or more frequencies

And Just One More Word…


• The ‘What If’ Issues…

• What if they don’t like it?

• What if they want a detailed explanation?

• What if I cannot match target?

Prescriptive Fitting


• The ‘What If’ Issues…

• Basis for Prescriptive Targets • Based on research regarding hearing loss AND

• Hearing aid user preferences

• A GREAT PLACE TO START

Prescriptive Fitting


Let’s see it done…


Adding a layer: Percentile Analysis

• Statistical method which evaluates the dynamic properties of the measured signal displaying the LTASS, the peaks and the valleys.

• The 99th percentile curve: the peaks of speech.

• The 30th percentile: the valleys of speech.

• Can see how much of the signal fits into the clients available dynamic range.

• Can recognize the effects of signal processing on the input signals

EUHA/AHA, 2011.


Percentile Analysis

LTASS

PEAKS

VALLEYS


Percentile Analysis

LTASS

PEAKS

VALLEYS


Aided Response – an Example


The added value of Percentile Analysis

• Visualizing the impact of compression settings on the signal arriving at the eardrum.

• Detailed assessment of HI features.

• Enhancement to the HI transition procedure.

• Explaining when targets are at or below threshold, or adding information when target cannot or is not met.


Percentile Analysis - Compression View

Add arrows to show compression at low/high diff. in dynamic range


Ave (percentiles) – use 65dB Input


Soft (percentiles) – use 55dB Input


Loud (percentiles) – use 75-80dB input


Speaking of not matching target…why is the target below audibility?

• Restoration of LTASS audibility of high frequencies is not always desirable.

• Prescribed gain to achieve audibility at higher frequencies may not be achievable.


MPO – Let’s See It Done…


A few comments…

• Manufacturer Preferred Algorithm

• Up versus Down; Frequency smoothing

• A contest between devices?

• The great equalizer

• Focus on product features, service options, support


Let’s Check with The Patient….

•Cox Loudness Scale


Loudness Acceptance

•Cox Loudness Scale

•GOOGLE:

memphis

cox

loudness

HARL


Loudness Acceptance


Loudness Acceptance


Loudness Acceptance


Loudness Acceptance

• Compare to Unaided

• Compare to Significant Other

• Decide to modify

• Consider Re-measuring Aided Responses


Loudness Acceptance – Let’s See it Done…

• Compare to Unaided

• Compare to Significant Other

• Decide to modify

• Consider Re-measuring Aided Responses

No verification Verification

Coupler Real Ear

Approach

First Fit only based on

audiogram

First Fit using measured

REUG/RECD

Verification in coupler using

predicted data

Verification in coupler using

measured data

Verification in real ear using

predicted REUG/RECD

Verification in real ear using

measured REUG/RECD

REUG/RECD Predicted Measured - read

from NOAH Predicted Measured Predicted Measured

Pediatric application X X X X > 5 yo > 5 yo

Adult application X X X X X X

Fitting software X X X X X X

HI Programming Interface

X X X X X X

AURICAL HIT (X) X X X

AURICAL FreeFit (X) X X X

Predictability of fitting quality: Pediatric

0 QQ QQ QQQQ QQQQQ QQQQQQ

Predictability of fitting quality: Adult

Q QQ QQQ QQQQ QQQQQ QQQQQQ

Quality improvement journey

Courtesy of Peter Kossek, Otometrics

Questions?

Please complete an

Evaluation Form for

this seminar

These presentations slides will be available to download at ihsinfo.org/convention


Taking customer care to a new level

THANK YOU!

[email protected]

www.AudiologySystems.com

Or please call us at:

855-283-7978

You can also find additional fitting resources at:

http://www.otometrics.com/Knowledge-Center/fitting

mailto:[email protected]

http://www.audiologysystems.com/




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Probe Microphone Measurements - International Hearing Societyihsinfo.org › IhsV2 ›...

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