Zusammenfassung
One reason for the poor pitch performance in current cochlear-implant
users may be the highly synchronized neural firing in electric hearing
that lacks stochastic properties of neural firing in normal acoustic
hearing. This study used three different electric stimulation patterns,
jittered, probabilistic, and auditory-model-generated pulses, to
mimic some aspects of the normal neural firing pattern in acoustic
hearing. Pitch discrimination was measured at standard frequencies
of 100, 250, 500, and 1000 Hz on three Nucleus-24 cochlear-implant
users. To test the utility of the autocorrelation pitch perception
model in electric hearing, one, two, and four electrodes were stimulated
independently with the same patterned electric stimulation. Results
showed no improvement in performance with any experimental pattern
compared to the fixed-rate control. Pitch discrimination was actually
worsened with the jittered pattern at low frequencies (125 and 250
Hz) than that of the control, suggesting that externally introduced
stochastic properties do not improve pitch perception in electric
stimulation. The multiple-electrode stimulation did not improve performance
but did not degrade performance either. The present results suggest
that both “the right time and the right place” may be needed to restore
normal pitch perception in cochlear-implant users.
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