Pitch perception in patients with cochlear implant.

概要

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Pitch perception was investigated in four cochlear implant (CI) patients.At first, the difference limen (D. L.). of pitch sensation conveyed by a stimulation rate was measured at each electrode in three CI subjects by the "Rate-pitch discrimination test" software program. At a fixed stimulation rate, D. L. was larger at the electrode near the round window. At most electrodes, D. L. decreased when the stimulation rate was increased. In general, D. L. was much larger than the acoustic performance in normal subjects.Secondly, a pitch recognition test was performed in two CI patients with two fixed electrodes. Two of the 9 complex synthetic tones, with fundamental frequencies which differed successively, were inputted randomly into the speech processor with the modified "map". The pitch perception performance of the CI patients was not satisfactory, and it was thought that in speech CI patients are unable to discriminate voice pitches.This may be explained as follows: either the CI cannot utilize the activity of neurons tuned only to pitch frequency, or the spectral pattern of complex tone is not transmitted by the CI because of the limited number of electrodes. Thus, the only coded information of pitch is a stimulation rate synchronized to voice pitch.
耳鼻咽喉科臨床学会の論文