Cochlear Implants: Speech Processor


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Fitting the Speech Processor (and Associated Assisted Listening Devices) 

After approximately a four-week healing process following surgery, it is then time to activate the external component of the implant called the speech processor. Each child's speech processor must be individually programmed. This is sometimes referred to as setting the child's "map." This process typically requires an initial appointment with an audiologist at the hospital implant center and several subsequent appointments during the following weeks. It is necessary to adjust the program frequently in the beginning as the brain adapts to incoming sound. Once a stable program has been obtained, the hospital implant center will determine how often to monitor a child in the coming months and years to assure that the program continues to provide adequate responses to sound. A child may be seen every two to three months for the first year and every six months for the second and third years depending on the recommendation of the hospital implant center.

Initial Sound Stimulation Listening through the implant for the first time may or may not be a positive experience. Each child reacts in a different way based on his or her prior experiences with sound. It is important that the audiologist adequately prepare the family regarding what to expect during a child's initial programming session, subsequent programming sessions, and early auditory responses. For more information, see:

MED-EL:

Cochlear Corporation:

Setting a Program

The basic components of determining a program include setting threshold levels (T levels), comfort levels (C Levels), and "flagging" (turning off) electrodes that may cause problems. A program is determined by setting each of the electrodes to be loud enough for a person to be aware of a sound, but not too loud as to cause discomfort.

During the initial programming session, an audiologist will determine and set the:

  • Electrode stimulation program/map (more than one program may be stored in the speech processor)
  • Volume setting
  • Sensitivity setting
  • Locks and controls (to prohibit children from changing settings inadvertently)

For young children, setting the program(s) of the speech processor is as much an art as a science. It is important that the audiologist doing the programming have experience working with young children. In addition to behavioral observation testing to document the child's responses, objective assessment tools that do not require a child's participation may also be utilized. Each manufacturer has software to objectively measure the responses of the neural fibers to electrical stimulation. These measures can confirm that the internal device is functioning and can help assist in setting the program of the external speech processor when it is activated. Not all hospital centers check neural responses during surgery or programming.

For more information about neural response tools:

About the Speech Processor Devices

Each manufacturer continues to update the design of its speech processors.

Upgrades

As each manufacturer develops new speech processors, it may be possible for individuals to replace older model processors with newer model processors while still maintaining the older generation of the internal device. It will be necessary to communicate with the hospital implant center to determine if an individual is eligible for the upgrade and if insurance will cover the cost.

Speech Processing Strategies

The speech processor converts sound to electrical impulses that represent speech. The cochlea is "tonotopic," with the base or bottom of the cochlea responsible for processing the high-frequency sounds and the apex of the cochlea responsible for processing the low-pitched sounds. The speech processor has the job of transforming sounds into electrical patterns to convey the sounds to the brain by stimulating the various parts of the cochlea. Each implant manufacturer uses speech processing strategies unique to its company.

For in-depth information on the strategies used by each manufacturer, see:

Assistive Listening Devices

In addition to the implant device itself, there are many associated assistive listening devices that may be used in conjunction with each cochlear implant to enhance listening in noise, at a distance, and with electronic devices.

For more information about the assistive devices available:

Cochlear Corporation-


MED-EL-

Coupling a Cochlear Implant to a Frequency Modulation (FM) System or Infrared System

There are various assistive technologies available to improve listening in background noise and at a distance in school, public areas, and at home. Two types of systems are Frequency Modulation (FM) systems and infrared systems.

When using an FM system, a child may use either a soundfield FM system or a system that provides direct input to his or her cochlear implant. Both systems utilize a transmitter/microphone to transmit sound.

With the soundfield system, the sound is broadcast via a small speaker placed strategically near the child or elsewhere in the classroom. With this system, everyone in proximity of the system's speakers will be listening as well. This may be a benefit or a distraction to others. If a child uses a soundfield system, there are no additional parts needed to couple the speaker to the cochlear implant or settings to change on the implant itself.

With a direct audio input system, sound is transmitted directly into the child's cochlear implant. Depending on which speech processor a child is using, there are various connectors or setting changes involved in coupling the FM system to the child's implant. There are a variety of FM manufacturers available that couple with each cochlear implant. While the benefits may be great, the setting and monitoring of a direct audio input FM system requires close care by the child's implant audiologist, educational audiologist, teacher, family as well as feedback from the child to assure that both FM as well as cochlear implant components are functioning.

For more information about FM devices and considerations:

With an infrared system, sound is transmitted using infrared light waves. Infrared systems can be used with microphones to transmit voice or can be connected to other sound equipment. For more information about the components of infrared systems:

Developed by Debra Berlin Nussbaum at the Cochlear Implant Education Center, Laurent Clerc National Deaf Education Center; last revised November 2013

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