Fitting and Evaluation of  FM Systems for  Cochlear Implant Users

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Cochlear Implants and FM Systems. THREE BASIC WAYS TO USE FM SYSTEMS WITH CIsAudio CouplingDesktop Soundfield FM systemsElectrical CouplingPatch cords connect FM Receiver to CIDirect Plug-in of FM ReceiverT-Coil CouplingProcessor has t-coil to receive electromagnetic signal from the Body-worn FM system with Neckloop.

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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


5. T-Coil Coupling- FM and CI

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 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. 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. 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

11. 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. 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. 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

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

15. 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. 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. 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. 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. 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. 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

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

24. ELECTROACOUSTIC PROCEDURES to 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. Purpose of Electroacoustic Testing with CIs and FM Systems Verify output for input to -CI microphone, and -FM transmitter microphone Determine FM advantage

26. 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. 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. 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. Processor Knob Control 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

30. 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. 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. 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 Connections for Testing Procedure

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

34. 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

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-------------


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