Fitting and Evaluation of FM Systems for Cochlear Implant Users

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Fitting and Evaluation of FM Systems for
Cochlear Implant Users

• Linda M. Thibodeau

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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

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Electrical Coupling- FM and CI

• BODY-LEVEL PROCESSORS
• COCHLEAR
• IMPLANTS EAR-LEVEL
• PROCESSORS
• BODY-LEVEL
• FM RECEIVERS RECEIVERS
• EAR-LEVEL
• RECEIVERS

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Body-worn Speech Processor
Ear-level Speech Processor

Body-Worn FM Receiver
Miniature Direct-Connect FM Receiver

Miniature Cord-Connect FM Receivers
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T-Coil Coupling- FM and CI
Requires Speech Processor with T-Coil such
as Nucleus 3G

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Verification Procedures for the CIFM Interface

• 1) Informal Testing
• 2) Behavioral Testing
• 3) Electroacoustic Testing

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Verification Procedures for the CIFM Interface

• 1) Informal Testing

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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

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Speaker for Cord-Connect and Direct Connect
Receivers
Informal Testing

• 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

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Monitor Earphones
Informal Testing

• 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 BTEs, but cannot listen to or plug in the
  FM at the same time

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Monitor Earphones
Informal Testing

• 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!

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Procedure for Using Monitor Earphones
Informal Testing

• Connect FM and monitor earphones
• Turn on Speech Processor, FM transmitter, FM
  receiver
• Speak into both CI and FM microphones separately

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Listening Check
Informal Testing

• 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
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Verification Procedures for the CIFM Interface

• 2) Behavioral Testing

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Behavioral Testing in the Booth
Behavioral Testing

• 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

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Testing Equipment for Speech Recognition
Behavioral Testing

• 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

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Setup for Testing a Child with a CI
Behavioral Testing

• ?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 childs hearing thresholds -Ideally
  35 dBSL

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Acronyms

• Cochlear Implant Alone
• BCI55
• BCI55/50
• Cochlear Implant FM System
• BFMCI55/50
• BFMCI55

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Measure Speech Recognition with CI alone
Behavioral Testing

• BCI55
• Measure SR in quiet with the CI alone
• BCI55/50
• Measure SR in noise with the CI alone at a
• 5 SNR

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Measure Speech Recognition with CI Interfaced
with FM System
Behavioral Testing

• Attach the FM system and verify functioning
• BFM/CI55/50
• Measure SR in noise with the CIFM at 5 SNR
• BFM/CI55
• If time permits, measure SR in quiet with the
  CIFM

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Compare Conditions
Behavioral Testing

• 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
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Behavioral Results Thibodeau, Schafer, Overson,
Whalen, Sullivan (2005)
Behavioral Testing

• 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 CIFM in
  Quiet was minimal.

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Verification Procedures for the CIFM Interface
Electroacoustic Testing

• 3) Electroacoustic Testing

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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

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Purpose of Electroacoustic Testing with CIs and
FM Systems
Electroacoustic Testing

• Verify output for input to
• -CI microphone, and
• -FM transmitter microphone
• Determine FM advantage

www.frye.com
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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

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Equipment for Electroacoustic Testing
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

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Equipment for Electroacoustic Testing
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)

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Processor Knob Control

• Sensitivity
• The quietest sounds that the speech processor
  will detect from the microphone and convert into
  stimulation

• Volume
• Modifies the intensity to the listener of that
  which has already been detected

G
Adapted from Nucleus 24 Technical Bulletin
December 1998-Febuary 1999 / Issue No. 6
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Equipment for Electroacoustic Testing
Electroacoustic Testing

• FM Transmitter Phonak Campus S
• FM Receivers-Set to Double Dots to get FM M
  Adaptor set to FMM

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Connections for Testing Procedure
Electroacoustic Testing

• 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

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Connections for Testing Procedure
Electroacoustic Testing

• 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

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Measurement Steps
Electroacoustic Testing

• Part I Input to CI mic
• Part II Input to FM mic
• Part III Compare Outputs

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Part IMeasuring RMS for Input to CI
Electroacoustic Testing

• 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

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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

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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

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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
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SUMMARY

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

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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

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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

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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

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