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Verifying Open-Ear Fittings With Speech-Mapping

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1 Verifying Open-Ear Fittings With Speech-Mapping
4/14/2017 AAA CEU Theater Program Verifying Open-Ear Fittings With Speech-Mapping Hello everyone. I want to thank you all for taking time away from your families and friends this evening to allow me to present what I think is a rather exciting proposal that promises to offer substantial benefit not only to the members of ADA, but to consumers, manufacturers, the industry and the profession of audiology. I have titled this presentation “Endowing Audiology’s Future” because I truly believe that the creation and management of financial resources that this plan extolls will indeed endow the profession of audiology in ways that have never before been achieved, and for many years, if not generations, to come. The Academy of Dispensing Audiologists (soon to become the Academy of Doctoring Audiologists) has built its reputation and its legacy by constantly challenging status quo and traditional beliefs. It is this constant desire to push the envelope for the betterment of the audiology profession that brings us here today. Can we once again challenge the traditions of thought and action that have yet to increase market penetration, or instill meaningful consumer trust and confidence, or protect the entrepreneur spirit that is the backbone of professional excellence? I believe we can. And I would like to spend the rest of my professional career working to build the resources and tools that will achieve these lofty goals. In this presentation, I aim to show each of you how I think this can be done. David J. Smriga, M.A. Audiologist Hearing Industry Consultant

2 Strom, Karl, “Rapid Product Changes Mark The New Mature Digital Market” Hearing Review
Vol. 13, No. 5, 2006 p.p.70-75

3 BTE Growth Spurt After 20% or less of the market in the ’80’s and ’90’s, look at BTE’s now: 26.4% in 2004 32.6% in 2005 42.00 in first half of 2006

4 Fueling That Growth Directional microphones Open fit hearing aids
27% of all BTE’s sold in first half of 2006

5 Why the Renaissance in Open Fit Popularity?
Minimal occlusion via a narrow tube fitting (or large vented earmold) Digital feedback cancellation Precise frequency response setting Mini (or micro) BTE designs Open-fit ITE design now available Directional microphones with open fit aids?

6 Minimal Occlusion Lybarger S. Earmolds. In: Katz J, ed. Handbook of Clinical Audiology, 3rd edition. Baltimore: Williams and Wilkins; 1985:

7 Digital Feedback Reduction Properties
Active Passive Phase Canceller Notch Filter

8 Precise Frequency Response/Compression Setting
Digital hearing instruments offer the most precise hearing instrument performance setting: Multiple bands Variable compression settings by band Low and multiple knee points Variable compression ratios This makes digital hearing aids dynamically interactive

9 Objective Verification of Open Fittings

10 Real Ear Basics Real-ear loudspeakers Probe Microphone Assemblies

11 Key Issues Input stimulus Traditional options Speech stimuli
Sweep frequency pure tone Noise stimulus Speech stimuli Activates adaptive features

12 The output of a compression aid depends on the nature of its input signal

13 The output of a compression aid depends on the nature of its input signal

14 The output of a compression aid depends on the nature of its input signal

15 Key Issues Insertion gain vs. audibility Traditional method
REUR – REAR = REIG Does this verify audibility has been delivered? Does this demonstrate “improvement” with open-fittings? Audibility method REAR compared to audibility threshold

16 For this compression hearing aid... Gain for speech @ Gain for tones
Oh good, it doesn’t matter which I use!

17 Output for speech is much less than output for pure tones.
4/14/2017 Output for speech is much less than output for pure tones. Maybe you should just listen to tones.

18 Speech Is An Excellent WDRC Measurement Stimulus
It IS the most important input signal that the patient will want to hear well and comfortably It interacts with multi-band compressors in a more realistic way than tones band interactions across frequency changing intensity

19 Understanding an SPLogram The Unaided SPLogram
Sounds get louder as you go UP the scale Maximum output targets Loud speech Avg. speech dB SPL Eardrum reference Soft speech Threshold (dB SPL TM) Normal hearing 1) Recruitment Accommodation

20 Example of Open-Fit REAR Result
Aid’s contribution Pink banana = REAR with aid OFF Green banana = REAR with aid ON

21 The SII Score

22 An Open-Fit Verification Protocol
Measure REAR with instrument on ear but turned off Measure REAR with instrument on ear and turned on Adjust gain to maximize SII without invoking feedback Use the fitting screen as a counseling tool

23 Can Directional Microphones Work In An Open Fit Environment?

24 The Aided Frequency Response That Reaches The Ear

25 Two Omni-directional Mics With Digital Processor
4/14/2017 Two Omni-directional Mics With Digital Processor DSP The first method has been around in one form or another for at least 20 years. The directional microphone is more sensitive to frontal sounds than to sounds from other directions. The sensitivity for frontal sounds, compared to the sensitivity averaged over all other directions is called the directivity index. This directly translates into the improvement in SNR that can be achieved when the wanted signal is directly in front and unwanted noise is coming from everywhere. For a good directional microphone, this can be as high as 5 dB. This translates into an intelligibility increase at least 50 percentage points. H. Dillon; NAL, CRC for CI and HAI

26 Measuring Directional Microphones Using Polar Plots

27 Laboratory Specification of Directionality
Polar Plots -20 -15 -10 -5 15 30 45 60 75 90 105 120 135 150 165 180 195 210 225 240 255 270 285 300 315 330 345 360 2) Directional Verification

28 Conventional Directional Microphone Test (Polar Plot Measurement)
Sound Field Speaker Pure Tone Frequency Anechoic Chamber

29 Issues Associated with Conventional Polar Plot Testing
Polar plots are obtained in the presence of a single pure tone frequency Polar plots do not measure in the presence of multiple input sources Polar plots can not be obtained in the presence of non-linear (compression) amplification

30 A New Way of Measuring Directional Microphone Performance
Obtaining a Directional Microphone Frequency Response in the Presence of Multiple Input Source Locations

31 Verifit Testing System Hardware
Coupler Chamber Secondary Signal Source Main Signal Source

32 Directional Frequency Response Input Stimulus
= Main input signal (512 pure tones 7.8Hz apart) = Secondary input signal (512 pure tones 7.8 Hz apart) Frequency (KHz)

33 Concept Behind Directional Box Test
Main Speaker Secondary Speaker

34 Clinical Verification of Directional Performance
B) Verifit REM Directional Verification Test selection Hearing Instrument Test Linear AGC Directional Distortion Input/Gain Multicurve Telecoil Manual control Calibration Real-Ear Measurement Speechmap Insertion gain Directional Manual control Calibration 2) Directional Verification

35 Directionality Test (REM)
Verifit System In REM Directional Mode Rear Facing Auxiliary Speaker Subject Aided Ear With Probe Tube Positioned 2) Directional Verification

36 On-Ear Directional Test Result
REAR to Front Signal REAR to Back Signal

37 Viewport Screen View Facilitates Results Comparison

38 Example of Complete Box-test Viewport Result

39 SRT-in-Noise Improvement With Open Fit Directional Mic
Fabry, D., “Facts vs. Myths: The ‘Skinny’ On Slim-Tube Open Fittings” Hearing Review, May, 2006

40 Conclusions Modern open-fits facilitated by:
Digital control of feedback Digital control of non-linearity Digital improvement in directional performance Objective on-ear measurements of open-fit products are possible Key elements to accomplish this: Speech input stimuli Measure eardrum SPL instead of gain Objective measures of directional performance are possible Can confirm directional function in aided area

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