Verifying Open-Ear Fittings With Speech-Mapping

1. Verifying Open-Ear Fittings With Speech-Mapping AAA CEU Theater Program 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: 885-910.

7. Digital Feedback Reduction Properties Passive Active 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 • 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. Oh good, it doesn’t matter which I use! For this compression hearing aid...Gain for speech @Gain for tones

17. Maybe you should just listen to tones. Output for speech is much less than output for pure 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. Loud speech Avg. speech Sounds get louder as you go UP the scale Soft speech Understanding an SPLogramThe Unaided SPLogram Maximum output targets dB SPL Eardrum reference 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 DSP H. Dillon; NAL, CRC for CI and HAI

26. Measuring Directional Microphones Using Polar Plots

27. 0 360 0 15 345 30 330 -5 45 315 60 -10 300 75 -15 285 90 -20 270 105 255 120 240 135 225 150 210 165 195 180 Laboratory Specification of Directionality Polar Plots 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. Obtaining a Directional Microphone Frequency Response in the Presence of Multiple Input Source Locations A New Way of Measuring Directional Microphone Performance

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

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