Guide to Cochlear Implants
Turning the Device On and Off
Each implant has an on/off dial or button. Parents are instructed in the proper sequence of turning the device on each morning. They can adjust the volume and sensitivity controls (see below) to ensure that their child begins the day with the device comfortably set. Some implants have the capacity to lock out all the controls, thereby preventing young children from manipulating them or turning the device off.
Setting the Volume and Sensitivity Controls
Through a series of external controls, the child, parent, teacher, or therapist can adjust the volume and sensitivity of the unit. Most parents are familiar with volume controls from the use of the child’s FM or hearing aid. These act in a similar manner on the cochlear implant. The volume control increases or decreases the loudness of the signal coming into the speech processor. Most parents, however, are not familiar with the concept of sensitivity adjustment. The sensitivity regulator changes the microphone’s ability to detect sounds that are either far away or close by. Think of the sensitivity control as a “bubble” around the implant user. If the sensitivity is set at a low level, the bubble is small and the microphone works best at detecting those signals inside the bubble. If the sensitivity is set at a high level, the bubble is larger and the microphone accesses sounds from a greater distance. Sounds outside the bubble may still be heard, but they will be softer in relation to the sounds inside the bubble. Each type of implant sets sensitivity by using units specific to that device. An implant center staff member will explain how to adjust the sensitivity of any given implant system and recommend appropriate settings for everyday use. It is important for parents, teachers, therapists, and, when appropriate, implant users to know about these settings to ensure that the device delivers the maximum amount of sound for a given situation.
Mapping Beyond the Initial Switch-On
MAPs will need to be changed periodically for as long as the child wears the implant. MAP adjustments occur more frequently during the first year of implantation than in subsequent years. Too many or too few MAP changes are not productive. When MAPs are changed too frequently, the child may not have enough time to adapt to sound. When MAPs are changed too infrequently, the child may be using a MAP that is not delivering enough sound to his or her auditory system. Parents are sometimes fearful that they will not recognize when a MAP change is required. More often than not, parents become expert in determining the need for a new MAP, since their daily interactions provide them with a baseline of performance from which to make this judgment. For example, parents may notice that their child is no longer responding to his or her name consistently. Parents who are unsure of their child’s mapping needs may contact the implant facility to help determine if the child will benefit from a new MAP.
Children return to the cochlear implant center then, on a regular basis, for re-mappings of the speech processor. The schedule of these appointments varies and is set by the individual implant facility. Generally, younger children return monthly during the first year of implant use; older children may require less-frequent re-mapping. At each mapping session after the initial switch-on, the child will receive two, three, or four MAPs (depending upon the type of device) to use over a period of time.