Ask the Audiologist:
Cochlear Implant Mapping
By Karrie Pargman, AuD
Doctor of Audiology, Elks Rehabilitation
How do I know if my child has a good cochlear implant map if I can’t listen myself?
Although you as a parent are unable to listen to what your child hears, there are some valuable tools you can use to check function of the implant at home. The most important method to check hearing and function of your child’s implant is to use the Ling 6 sound test. The Ling 6 sounds are: m, ah, ee, oo, sh, and s. Ask your child to repeat what he or she hears for these sounds on a daily basis, ideally first thing in the morning. The Ling 6 sound test is a simple test that is designed to check that the child is able to either detect or discriminate particular sounds that cover the full range of speech sounds and frequencies in “the speech banana,” or the banana shaped range of usual frequencies and decibel area of speech sounds. The Ling sounds are available on printed index cards through your audiologist, speech therapist, or implant manufacturer. When a child is taught to pair the Ling sounds with an action or animal when they respond, even a very young child can describe what they are hearing.
Cochlear implants are programmed or “mapped” by a cochlear implant audiologist working along with the child’s responses, even with a very young child. Behavioral mapping requires the child to indicate when he or she has heard a specific sound. An electrical stimulus (sound) is sent to the implant through the computer. Some children are able to indicate that they’ve heard the sound in a wide variety of ways, depending on their age, listening experience, and cognitive abilities. Games such as dropping a block in a bucket, stacking pegs, or raising a hand are examples of behavioral responses. Other children are too young or inexperienced, and we look for other types of responses to the sound, such as turning their heads, blinking, or pausing while playing with a toy. Early intervention programs should encourage and teach listening games at home to help make testing more fun (or at least take less time and frustration) for the child. After activation of the implant, the audiologist will get a baseline audiogram and detection thresholds (the softest sound your child can hear) during appointments. Generally you can expect your child to respond to sounds between 15 and 30 decibels with an implant. It is important to remember that even if your child tests within the range of near normal hearing, they do not hear normally.
How do you know how well your child is using the implant?
The purpose of cochlear implants (speech processors) is to allow people with severe and profound hearing loss to hear speech at normal to soft levels, both when it’s quiet, but also in noise. In order to determine whether a child is receiving access to speech sounds, audiologists assess what the child is able to hear in a controlled environment—the sound booth. There are many types of aided test measures. One of the easiest and most valuable tools is speech perception testing. This may be in the form of sounds, words, or sentences, and in quiet or in background noise. We use speech perception testing to tell how a child is hearing, if the cochlear implant is functioning well, and if there are changes that need to be made to the map. It is also possible to test the benefit a child receives from an FM system using these test procedures.
Speech perception testing may be completed formally in the soundbooth or informally in the office. This typically includes vowel and consonant tests, picture pointing tasks, single word lists, and sentence tests in both the open set (no choices) and closed set (typically a choice of 4 or 6). When your child is asked to repeat “baseball, airplane, ice cream” you are seeing speech perception testing at work. As your child gets older, the challenge of background noise is added, and the audiologist will determine the possible need for an FM system. Typically, the audiologist will use standardized testing in a sound booth to measure specific, controlled levels, compare to past results and compare to the norms for other children. If your child uses two implants, testing should be conducted with each ear independently, and with both ears together. Testing in noise gives better information about how your child uses the implant in real life situations. If a child can’t fully participate, the audiologist will continue exposing them to age and /or developmentally appropriate test conditions until reliable results and verification of proper programming is obtained. Often, a second person in the soundbooth is needed to be able to observe the child in addition to a parent for best results.
How often does a child need mapping?
Most children need a new “map” over time. Parents and school professionals who regularly check function with the Ling sounds ensure that a child gets in to the audiologist for mapping as needed. Eventually, an older teen learns to check their own Ling sounds as they will be responsible in adulthood to seek audiology support. Regular testing can also assess the integrity of the cochlear implant. The younger the child is or the newer the implant, the more often they are typically tested. For school age children, it is beneficial to have aided testing completed at least twice a year. At a minimum, annual testing is considered appropriate for the purpose of comparing current test results to previous test results.
Call for an appointment if you notice a change. If your child is asking “What?” more often, turning up sound or sitting closer to the television, having difficulty at school, experiencing any discomfort, or unable to repeat or detect all Ling 6 sounds without hesitation, it’s time to check the mapping and the equipment.
More questions? Contact me at kpargman@elksrehab.org.
Notes:
1. For more information on the Ling 6 Sound Test, see
http://hope.cochlearamericas.com/sites/default/files/
sound_foundation/SF_Ling_6_SoundTest.pdf
2. A previous article on progressive hearing loss suggested monitoring a child’s hearing at home using the six Ling sounds mentioned here plus the additional /p/, /t/, /k/, /f/ /d/ and /g/ sounds to check hearing regularly. These additional "Ling Plus" responses can give your audiologist valuable information.
3. For more information about hearing age and the expected development of listening skills after implant activation, see this checklist from Advanced Bionics at (link) www.advancedbionics.com/
4. More on Speech Perception Testing: http://www.audiologyonline.com/
5. Videos of the Ling Test:
http://is-learn.esc11.net/stiggs/speech/speechmoduleedited3.html |
