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Figure 5.1. Child connected to programming station and equipment
Adjusting the Electrical Levels
Once all the external and internal components are linked, the process of setting the electrodes begins. The programming audiologist activates each of the individual implanted electrodes one at a time. The purpose of this procedure is to determine the level of electrical stimulation that each electrode requires for producing a response in the child. The lowest level of current that is needed to get an auditory response is called the threshold or T-level. These responses can be conditioned responses (e.g., the child responds to the stimulated electrode by placing a block in a bucket or a peg in a board) or observed responses (such as eye movement). Implant devices, which incorporate a system known as Neural Response Telemetry (NRT) (described in chapter 3), enable the clinician to obtain these measures in a more objective manner. NRT has proven to be a reliable tool for programming implants in children too young to provide feedback during tuning.