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Fitting and Evaluation of FM Systems for Cochlear Implant Users

Fitting and Evaluation of FM Systems for Cochlear Implant Users. Linda M. Thibodeau. Cochlear Implants and FM Systems. THREE BASIC WAYS TO USE FM SYSTEMS WITH CIs Audio Coupling Desktop Soundfield FM systems Electrical Coupling Patch cords connect FM Receiver to CI

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Fitting and Evaluation of FM Systems for Cochlear Implant Users

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  1. Fitting and Evaluation of FM Systems for Cochlear Implant Users Linda M. Thibodeau

  2. Cochlear Implants and FM Systems THREE BASIC WAYS TO USE FM SYSTEMS WITH CIs Audio Coupling Desktop Soundfield FM systems Electrical Coupling Patch cords connect FM Receiver to CI Direct Plug-in of FM Receiver T-Coil Coupling Processor has t-coil to receive electromagnetic signal from the Body-worn FM system with Neckloop

  3. Electrical Coupling- FM and CI BODY-LEVEL PROCESSORS COCHLEAR IMPLANTS EAR-LEVEL PROCESSORS BODY-LEVEL FM RECEIVERS RECEIVERS EAR-LEVEL RECEIVERS

  4. Body-worn Speech Processor Ear-level Speech Processor Body-Worn FM Receiver Miniature Direct-Connect FM Receiver Miniature Cord-Connect FM Receivers

  5. T-Coil Coupling- FM and CI Requires Speech Processor with T-Coil such as Nucleus 3G

  6. Verification Procedures for the CI+FM Interface • 1) Informal Testing • 2) Behavioral Testing • 3) Electroacoustic Testing

  7. Verification Procedures for the CI+FM Interface 1) Informal Testing

  8. Informal Testing Informal Testing • Can be performed by the classroom teacher • Quick and easy way to determine that CI and FM are functioning • 3 Types: 1. Using a speaker 2. Using monitor earphones 3. Performing a listening Check – subjective response required from child

  9. Informal Testing Speaker for Cord-Connect and Direct Connect Receivers • Plug the FM receiver into an amplifier speaker: Radio Shack Mini Amplifier Speaker (Cat. No. 277-1008C) • Speak into the transmitter microphone • Listen to the output through the amplifier speaker

  10. Informal Testing Monitor Earphones • Can hear output from CI mic. before it is processed and sent to the electrode array • Can hear output for input to CI and FM simultaneously • Available for Nucleus Processors: 1. ESPrit 3G BTE 2. SPrint Body-Worn ESPrit 3G with Monitor Earphones SPrint with Monitor Earphones --Can listen to output from input to CI microphone for ESPrit 22 and 24 BTE’s, but cannot listen to or plug in the FM at the same time

  11. Informal Testing Monitor Earphones • Other BTE speech processors that have monitor earphones • ESPrit 22 • ESPrit 24 Can listen to output when there is input to CI microphone via the earphone, but cannot plug in the FM Receiver at the SAME time!

  12. Informal Testing Procedure for Using Monitor Earphones • Connect FM and monitor earphones • Turn on Speech Processor, FM transmitter, FM receiver • Speak into both CI and FM microphones separately

  13. Informal Testing Listening Check KEY TO LISTENING CHECKS: Must give input to both microphones separately • Have the child repeat or act out what you say: 1. Ling – ah, oo, ee, sh, ss, mm 2. Numbers – one, two, three 3. Count syllables – ba, ba, ba 4. Long or short – baaaaa, ba ba ba 5. Simple commands – Hide your face 6. Speech awareness with play – rings, blocks, etc www.cochlearamericas.com

  14. Verification Procedures for the CI+FM Interface 2) Behavioral Testing

  15. Behavioral Testing Behavioral Testing in the Booth • A modified ASHA procedure is used for behavioral testing with FM systems Speech recognition is the most effective way to measure behavioral benefit with an FM system

  16. Behavioral Testing Testing Equipment for Speech Recognition • Soundbooth with soundfield speaker and seating at a zero degrees azimuth • Audiometer that allows for live voice speech recognition (SR) testing • Appropriate SR material with multiple lists

  17. Behavioral Testing Setup for Testing a Child with a CI Seat the child at 0 degrees azimuth • Check CI functioning with monitor earphones or informal listening check Select presentation level for stimuli that is appropriate for the child’s hearing thresholds -Ideally 35 dBSL

  18. Acronyms • Cochlear Implant Alone • BCI55 • BCI55/50 • Cochlear Implant + FM System • BFMCI55/50 • BFMCI55

  19. Behavioral Testing Measure Speech Recognition with CI alone • BCI55 Measure SR in quiet with the CI alone • BCI55/50 Measure SR in noise with the CI alone at a +5 SNR

  20. Behavioral Testing Measure Speech Recognition with CI Interfaced with FM System • Attach the FM system and verify functioning • BFM/CI55/50 Measure SR in noise with the CI+FM at +5 SNR • BFM/CI55 If time permits, measure SR in quiet with the CI+FM

  21. Behavioral Testing Subject CI/FM CI: Quiet CI: Noise CI+FM: Noise Case #1 3G/MLxS 92% 72% 88% Case #2 3G/MLxS  92%  68% 84% Compare Conditions • Compare percent correct scores with and without use of the FM System • Two most important conditions for comparison are: BCI55/50 and BFM/CI55/50 • Case studies for Two Children Using Nucleus 3G Processors and Phonak MLxS Receivers Stimuli: PBK words; Presentation levels: case #1, 65/60; case #2 55/50

  22. Behavioral Testing Behavioral Results Thibodeau, Schafer, Overson, Whalen, Sullivan (2005) BCI55/50 45.50 % (CI alone) BCIFM55/50 75.25 % (CI + FM) The average improvement when adding the FM system in noise was 29.75% BCI55 76.00% BCIFM55 75.24% The difference between CI alone and CI+FM in Quiet was minimal.

  23. Electroacoustic Testing Verification Procedures for the CI+FM Interface 3) Electroacoustic Testing

  24. ELECTROACOUSTIC PROCEDURESto Evaluate FM systems with Cochlear Implants • New Monitoring Earphones provide a convenient way to monitor the output of the CI microphone relative to that of the FM microphone prior to being delivered to the electrode array. • Only Nucleus 3G and Sprint Processors allow this earphone to be attached AT THE SAME time as the FM Receiver

  25. Electroacoustic Testing Purpose of Electroacoustic Testing with CIs and FM Systems • Verify output for input to -CI microphone, and -FM transmitter microphone • Determine FM advantage www.frye.com

  26. Electroacoustic Testing Electroacoustic Testing • Acoustic output from a CI monitor earphone is used to verify functioning and to measure the FM advantage • Currently available on Nucleus ESPrit 3G and SPrint • A modified ASHA procedure is used for testing the FM systems electroacoustically

  27. Electroacoustic Testing Equipment for Electroacoustic Testing • Speech processor • Monitor earphones • Hearing aid analyzer: Fonix FP40 • Coupler: ½ to 1 inch adaptor OR Adaptor cord from Speech Processor to analyzer

  28. Electroacoustic Testing Equipment for Electroacoustic Testing ESPrit 3G – One Control either programmed for Sensitivity or for Volume Units today are set: P1-Sensitivity (Range 1-7) P2-Volume (Range 1-7) SPrint Separate Controls for Volume – Middle no. on display (Range 1-9) Sensitivity – Right no. on display (Range 1-20)

  29. Volume Modifies the intensity to the listener of that which has already been detected Sensitivity The quietest sounds that the speech processor will detect from the microphone and convert into stimulation Processor Knob Control G Adapted from Nucleus 24 Technical Bulletin December 1998-Febuary 1999 / Issue No. 6

  30. Electroacoustic Testing Equipment for Electroacoustic Testing • FM Transmitter: Phonak Campus S • FM Receivers-Set to Double Dots to get FM + M Adaptor set to FM+M

  31. Electroacoustic Testing Connections for Testing Procedure • Connect the CI speech processor and the FM receiver 2. Plug the monitor earphones into the speech processor 3. Connect the ½ to 1 inch adaptor to the test microphone or use adaptor cord

  32. Electroacoustic Testing Connections for Testing Procedure 4. Fit one earphone into the coupler or plug into analyzer 5. Place the coupler and earphone in a stable location outside the analyzer 6. Turn on the processor, receiver, and transmitter

  33. Electroacoustic Testing Measurement Steps Part I: Input to CI mic Part II: Input to FM mic Part III: Compare Outputs

  34. Electroacoustic Testing Part I:Measuring RMS for Input to CI 1. Position processor in test box and close lid 2. Present 65 dB SPL complex signal: ECI/FM65 3. Place transmitter in quiet location 4. Record RMS for that Setting

  35. Part II: Measuring RMS for Input to the FM Transmitter 1. Place transmitter microphone in test box and close lid 2. Present 80 dB SPL complex signal: EFM/CI80 3. Place processor in quiet location 4. Record RMS for that Setting

  36. Part III: Calculate FM Advantage • FM Advantage = EFM/CI80-ECI/FM65 (RMS Difference) • Ideal FM advantage is at least 10 dB • If speech processor is set for sensitivity, adjust sensitivity knob to improve FM advantage if necessary

  37. FM Advantage as a Function of Sensitivity Setting on the 3G MLxS programmed to +10 and +24 Advantage via Toasting Volume programmed to default (100% of Electrical Dynamic Range, equivalent to 9 on SPRINT) FM Advantage = RMS Difference between EFM/CI80 and ECI/FM65

  38. SUMMARY • FM Fittings must be verified in one or more ways • Informal Testing • Behavioral Testing • Electroacoustic Testing

  39. SUMMARY • Informal Testing Should be part of daily routine when FM is connected to CI Students should be reinforced when they alert adult that system is not working

  40. SUMMARY • Behavioral Testing Recall that if using Percent Correct scores, large differences are needed to be significantly different Necessary to verify FM advantage when electroacoustic testing cannot be performed

  41. SUMMARY • Electroacoustic Testing Can be done for those systems that allow the addition of the monitoring earphone while the FM is connected Necessary to verify FM advantage

  42. SUMMARY Given the risks, costs, and commitment associated with obtaining a Cochlear Implant… It only makes sense that one would do everything possible to provide the most optimal signal…. THEREFORE-------------

  43. CONSIDER FM SYSTEMS FOR EVERY EAR OF EVERY CHILD AND VERIFY FM FITTINGS WITH COCHLEAR IMPLANTS SO THAT…..

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