[Examination to possibilities of a physiological fitting of cochlear implants]

Cochlear implants (CI) convert acoustic events into electrical pulses. The auditory nerve picks these tiny electrical pulses up and sends them to the brain. The dynamics of the audible sound is compressed considerably. The limits for stimulation are determined with the patient. A map law determines which sound pressure level is assigned to which stimulation level. A sufficient speech understanding requests an allocation of high stimulation levels for weak sound signals. The higher the sound level, the lower the increase. Unfortunately, with such kind of map law unwanted background noise is also presented as well audible stimulation. These stimuli are often annoying to CI users in everyday situations.

The possibility to give an s-shaped course to these map laws was examined in 9 patients. After the fitting procedure their speech understanding were tested. The results were compared with the results of former tests.

8 patients reported definite improvement of their hearing situation. Such map laws seem, therefore, suitable to optimise speech processor programming.