Mapping a Cochlear Implant

Mapping (or MAPping) is the term for programming a cochlear implant to the specifications and needs of its user.  While any cochlear implant user, or parent, caregiver, or family member of a CI user, has probably attended countless mapping appointments with an audiologist, the process is often confusing or poorly understood.

 We go to the audiologist, he or she presses some buttons and adjusts somethings on the computer, a new MAP is made, and we go home, knowing little more about the process than when we entered the appointment room.  Here are some basics to help you understand the mapping process and get more out of your/your child’s next appointment.

MAPs are programs that help to optimize the cochlear implant user’s access to sound by adjusting the input to the electrodes on the array that is implanted into the cochlea.  While each cochlear implant company has different terminology, different programming strategies, and different capacities for various MAPs on their processors, the basic ideas behind MAPping hold true for all three FDA-approved brands.  The cochlear implant processor is connected to the audiologist’s computer for MAPping.  Using a series of “beeps,” and measuring the CI user’s response (see ways of measuring audiological responses HERE), the audiologist sets T- and C- levels for each electrode.  T-Levels, or Thresholds, are the softest sounds the CI users can detect.  C-Levels (also sometimes called M-Levels), are Comfortable loudness levels that are tolerable for the CI user.  The audiologist might also adjust the stimulation rate or programming strategy used for the MAP — these refer to the various computer algorithms and programs used to translate acoustic sound (what people with typical hearing perceive) into the correct combination of electrode stimulations to give the cochlear implant user that same sensation of sound.

Here are some Dos and Don’ts for getting the most out of your mapping appointments:

  • DO come well-rested, well-fed, and ready to concentrate.  For young children, it often helps to bring a favorite toy (not one that is too noisy or distracting, though) or snacks.

  • DON’T forget your gear.  Bring your remote, FM system, backup processor(s), music link accessories, etc.  If you’ve got it, bring it!

  • DO prepare notes and observations about your hearing performance to help guide the audiologist to your best program.  What listening situations are difficult for you?  Which are easy?  What sounds good and what doesn’t sound quite right?  What changes have you noticed since your last MAPping appointment?  How has this MAP affected your access to sound or the sound of your speech?  Are you relying more or less on speechreading or visual cues?  How does music sound?  What do your child’s teachers and therapists report?  It is helpful to keep a “hearing diary” continuously between appointments — this is not something to pull together in the car on the way to the audiologists’ office.

  • DO come with questions!  Write them down before the appointment so you don’t forget any crucial information.

  • DON’T rely solely on NRT (Neural Response Telemetry) for your children or CI users who are, for whatever reason, unable to respond.  Put simply, NRT measures the nerves’ responses to the “beeps” stimulating the CI from the audiologist’s computer.  While it can provide valuable information, beeps and neural responses do NOT directly translate to hearing performance.  A skilled audiologist will also use Behavioral Observation Audiometry, Visual Reinforcement Audiometry, Conditioned Play Audiometry, or Conventional Audiometry (depending on the patient’s age and developmental levels) to measure the listener’s response in a more “real” situation.  An NRT sweep is a rough estimate compared to the assessment of a skilled audiologist in a behavioral response situation.

  • DO choose an audiologist who has experience with children.  MAPping children and MAPping adults are completely different ball games.  A good pediatric audiologist, one who can hold the child’s attention while getting high quality MAPs, is worth his or her weight in gold!

  • DON’T forget speech perception testing in the booth.  After a new MAP is made, booth testing, specifically booth testing for speech perception and listening in noise, are not-to-be-missed final steps.  Listening to beeps is fine — but real life is not listening to beeps!  If the MAP does not improve the CI user’s speech perception and/or listening in noise, it’s time to go back to the drawing board (or laptop, as the case may be!).

Frequent, high quality MAPping is key to optimizing performance with a cochlear implant.  Many centers have a set protocol for the initial stimulation and series of follow-up appointments.  Over time, MAPs may stabilize and audiology appointments will become less frequent.  Indicators that you/your child might need a new MAP include:

  • Complaints of things sounding too quiet, distorted, or unclear

  • Changes in listening performance (missing quiet phonemes like s, th, f, etc., difficulty listening in noise)

  • Changes in speech production (sounding slushy, having sloppy speech, changes in sounds previously achieved)

  • Hormonal changes and growth spurts may also necessitate a new MAP

  • As the CI user’s listening skills grow, he/she may be ready for more “power” in a MAP, and might need an adjustment

WHAT IS THE GOAL?

The “gold standard” of a good MAP would be thresholds between 15-20dB across the board through 6000Hz, with aided speech discrimination scores in quiet and loud speech, as well as speech in noise, in the 90%+ range.  Why?  Hearing “in the speech banana” is just not enough.  If your thresholds are, say, at 30dB, yes, technically that is “in the speech banana” — but it leaves you little/no wiggle room for understanding speech in noise.  Similarly, if your thresholds are only good through 4000Hz, you’re missing a ton of high frequency information, especially consonants like s, f, and th, when spoken by female or child voices.  Some audiologists think it is sufficient to set a new MAP and send you on your way — not so!  While beeps on a computer and pure-tone thresholds are great, they do not tell us how the CI user is functioning with actual speech stimuli.  Aided speech discrimination testing is key, and we’re looking for “A” grade scores (90%+).  After all, who wants to be guessing more than 10% of the time in everyday conversation?  How exhausting!

When in doubt, contact your audiologist!  A good relationship with a skilled professional will have you on the road to your personal best hearing performance.

Advertisements

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s