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Verifying Open-Ear Fittings With Speech-Mapping David J. Smriga, M.A. Audiologist Hearing Industry Consultant AAA CEU Theater Program.

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Presentation on theme: "Verifying Open-Ear Fittings With Speech-Mapping David J. Smriga, M.A. Audiologist Hearing Industry Consultant AAA CEU Theater Program."— Presentation transcript:

1 Verifying Open-Ear Fittings With Speech-Mapping David J. Smriga, M.A. Audiologist Hearing Industry Consultant AAA CEU Theater Program

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  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 Phase Canceller Passive Active 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 loudspeakers Real Ear Basics Probe Microphone Assemblies

11 Key Issues Input stimulus  Traditional options  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

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

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

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 H. Dillon; NAL, CRC for CI and HAI DSP

26 Measuring Directional Microphones Using Polar Plots

27 Laboratory Specification of Directionality Polar Plots 2) Directional Verification

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

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

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

33 Concept Behind Directional Box Test Main Speaker Secondary Speaker

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

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

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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