Tone decay at threshold with auditory electrical stimulation in digisonic cochlear implantees.

The present study aims to evaluate tone decay (auditory adaptation) in Digisonic cochlear implant patients, and to compare tone decay results with speech recognition performance. The following criteria are evaluated: tone decay occurrence, place effect, pulse rate effect, and correlation with speech recognition. A great variability in tone decay was found among the subjects. The amount of tone decay, measured as a percentage of the electrical dynamic range, depends to some extent on electrode location, which may be linked with the frequency dependence of acoustical tone decay. However, it is likely that acoustically and electrically evoked adaptation does not involve the same process. Also, an effect of pulse rate was found. However, no relationship between the amount of tone decay and speech recognition abilities was observed. Evaluation of tone decay in cochlear implant patients might not only allow further evaluation of the condition of their auditory system, but also provide a means to determine preoperatively the specific characteristics of a subject's residual auditory capacities.