Auditory simulation of cochler implant using mel scale.

概要

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The nature of the voice sounds which cochlear implant (CI) patients "hear" is not well known. We input five Japanese vowels/u, o, a, e, i/into the CI, and recorded the exact time of discharge and position of active intracochlear electrodes. To simulate the vowels which CI patients hear, we digitally synthesized tone bursts of characteristic frequencies at stimulated portions, and arranged them according to the timing of stimulation on the time axis.Next, we improved the quality of simulated vowels using formant shifting by the mel scale which represents a psychophysical relationship between perceptual pitch and actual frequency.We evaluated the efficacy of this scale in two CI patients through a discrimination test among synthesized vowels which emulate mel scale shifting by activating appropriate electrodes.Simulated vowels were like a "Donald Duck" voice, but distinguishable from each other to some extent after repetition. Mel scale shifting improved discrimination by normal subjects and also by CI patients. These results suggest that patients may hear more intelligibile vowels with the use of the mel scale.
耳鼻咽喉科臨床学会の論文