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