Cochlear implant speech processor frequency allocations may influence pitch perception.
OBJECTIVE
To investigate the effects of assigning cochlear implant speech processor frequencies normally associated with more apical cochlear locations to the shallow insertion depths of the Iowa/Nucleus Hybrid electrode.


METHODS
Subjects using the Hybrid implant for more than 1 year were tested on speech recognition with Consonant-Nucleus-Consonant words and consonant stimuli. Pitch sensations of individual electrodes were also measured electrically through the implant and acoustically in the contralateral ear.


METHODS
Tertiary care center.


RESULTS
Most subjects showed large improvements in speech recognition within 12 months after implantation. Furthermore, after longer periods of 24-plus months, some individuals were able to achieve high levels of consonant discrimination with electric-only processing comparable to long-electrode patients with deeper electrode insertions. Pitch perceptions obtained from individual electrodes in these subjects were closer to the frequency map assigned an electrode than the place-frequency predicted from cochlear location.


CONCLUSIONS
These results suggest that over time, pitch sensations may be determined more by the implant map than by cochlear location. In other words, the brain may adapt to spectral mismatches by remapping pitch. Furthermore, patients can perform well with shifted frequency allocations for speech recognition. The successful application of shifted frequency allocations also supports the idea of shallower insertions and greater preservation of residual hearing for all cochlear implants, regardless of the patient's frequency range of usable residual hearing.
Reiss
Lina A J
LA
Department of Speech Pathology and Audiology, The University of Iowa, Iowa City, Iowa 52242, U.S.A. lina-reiss@uiowa.edu
Gantz
Bruce J
BJ
Turner
Christopher W
CW
D000328:Adult; D000368:Aged; D003054:Cochlear Implants; D004566:Electrodes; D005260:Female; D007839:Functional Laterality; D006801:Humans; D008297:Male; D008875:Middle Aged; D010898:Pitch Perception / Q000502:physiology*; D013067:Speech Perception / Q000502:physiology*; D016896:Treatment Outcome