University of Edinburgh

Trouble-shooting Cochlear Implants Day-to-day Management, including FM Systems

Presented on 27 February 2008

Linking up to FM systems practical tips and suggestions

Ear Foundation

Elizabeth Wood South of England Cochlear Implant Centre
University of Southampton

Which type of FM system?

  • All personal FM radio aids are compatible with cochlear implants, but discuss options with the implant centre before purchasing/fitting.
  • Radio aids are provided by local services.
  • If the child is very young a portable or fixed soundfield system may be advantageous.

What about Soundfield FM?

  • Soundfield FM, or Infra-red systems give benefit to all children and teachers.
  • Soundfield FM in addition to a personal FM is recommended providing:
    - The room acoustics are good before the soundfield is installed
    - Care is taken to ensure that the soundfield is functioning optimally

Note: We did a small research study which involved recording a short speech passage through a Sprint speech processor, in soundfield treated classrooms and halls, together with and without a radio aid. The sound quality was rated in the different settings and we found that the ratings were poorest in the halls which had not been acoustically treated before the soundfield system had been installed. The implant users expressed a preference for wearing the radio aid alone in these halls, but were happier using the two systems together in rooms which had good acoustics.

When to fit an FM system

Discuss with implant centre professional to decide if the child is ready

  • Can the user indicate sound quality?
  • Is their map stable
  • may need to discuss which transmitting frequency to use

At SOECIC we recommend that the initial fitting takes place at CI centre

  • For a Freedom, a map will be created with 1:1 mixing, and a map for checking will be created
  • For an ESPrit 3G the FM map needs to have monitor earphones disabled
  • The FM connecting lead is provided by SOECIC (may differ with other implant centres)
  • Wearing position and interference issues can be discussed
  • An information sheet/booklet is provided

Note: When is it an appropriate time to fit an FM system?
Initially discussions will take place with local professionals as the education services provide the radio aid
We need to ensure that the implant wearer is able to indicate sound quality, and that their map is stable.

SOECIC Fitting Procedure

Listening check of FM radio aid, adjust settings and check speech processor
New objective test-box method for setting up levels (lead and method developed by Ewing Foundation Technicians)

fitting procedure

Validate the settings with a speech test (McCormick ATT)

Note: As I mentioned previously we recommend the initial fitting takes place at the implant centre.
We check the radio aid, set any internal switches, listen to it, then set it an appropriate volume for the user.
The processor will be listened to if possible, and the appropriate map selected for the 3G with the monitor earphones not enabled.
The sequence for connecting the systems is to start with both the processor and FM systems switched off. The FM cable is connected, then the radio aid transmitter switched on, then the FM receiver and finally the speech processor.
Then we validate the Fm receiver setting by using the McCormick ATT, firstly without the radio aid, then with the radio aid. We would expect to show approximately a 10-15 dB better result.
We give an FM booklet which details the settings and instructions for the school, and two small summary cards detailing the user's map programmes.


Transmitter frequencies
for Nucleus CI24 series 173.350 - 173.750 MHz
for Nucleus CI22 series 173.750 - 174.400 MHz
for Medel and Advanced Bionics processors any frequencies can be used

Receiver volume
Sprint Esprit 3G Freedom Tempo+
Genie 5-6 4-5 5-6 3-4
CRM 220 OLS 250 OLS 75 Discuss + centre
Solaris 7-8 5 5 4

Radio Aids fitted at SOECIC Sept 2007
N=108 fitted out of total 199 children/teens

pie chart

Ear-level FM with Nucleus Freedom

hearing aids

Ear-level FM with other processors

Advanced Bionics
with Harmony bte
use i-connect earhook

advanced bionics

with Opus 2 bte
use FM battery pack


Nucleus Freedom with a body worn FM

The Freedom is being used successfully with ConnevansGenie and Solaris FM systems. Use the correct FM cable eg FM15E for Genie.

Volume setting on the Genie and Solaris was set as for the 3G (may need to be slightly higher for Genie).

Body-worn FM with other speech processors

Advanced Bionics with Harmony
bte use direct-connect earhook
eg; with Solaris

advanced bionics

Medel with Opus 2 use FM cable
directly into battery pack
With Tempo+ use FM cable into
angled battery pack


Checking an FM is working with a Nucleus speech processor

To listen to the combined signal - take processor off patient and switch off

  • Use the patient's 'FM' map – for a Freedom usually P1
  • For an Esprit 3G select programme with monitor earphones enabled.
  • Connect earphones to processor, switch on FM system and connect to CI, switch on processor and listen over a distance.

To listen to FM alone – change to checking programme

  • For a Freedom, use 'increase/decrease buttons' to reduce the speech processor sensitivity to 0.
  • For an ESPrit 3G, turn sensitivity to 0.
  • Connect as above, and with monitor earphones as above and listen to FM alone.
  • Return sensitivity to recommended setting.
  • Return processor to recommended FM programme.

Freedom MicroLink

Fittings have been made at SOECIC to older patients who can report back on sound quality and can do a speech in noise task.


  • Need a programme for checking with variable sensitivity.
  • Gain/volume setting has been less than the Cochlear/Phonak recommendations.
  • Costs to local services for buying new equipment.
  • Interference issues
    May be some issues if using multi-frequencies in a school Transmission range may not be very long.
    May be areas in a room with poor reception.
    Do not use Phonak frequencies 01 and 02 (interference from
    transmitter coil).

Tips to try… If the FM does not seem to be working

  • Check the FM system and speech processor.
  • For a Freedom, may need to re-activate the accessory by pressing the increase/decrease buttons until EA shows.
  • Replace FM lead/accessory adaptor.
  • For a MicroLink system re-synchronise the Transmitter and Receiver.
  • Switch the speech processor off and on again when connected to the FM.

Tips to help with interference problems

  • Check the correct programme is being used.
  • Try a different transmitting frequency.
  • Try a different gain with a MicroLink receiver.
  • Try a different receiver or transmitter.
  • Listen to see if you can hear the problem using a digital aid connected to an FM system – may be helpful if there is IT equipment/smoke alarms/whiteboards nearby.
  • Is it a distance/range/position in the room problem?

Working together

Local Services

  • Provision and maintenance of FM
  • Day-to day management
  • Liaison with school, family and CI centre
  • Training for staff

CI Centre

  • Initial fitting and validation
  • Provision of lead/adaptor
  • Troubleshooting
  • Training
  • Provision of handouts


  • Report on sound quality
  • Provide feedback


  • Support and encourage
  • Liaise with school and CI centre