Neural tonotopy in cochlear implants: an evaluation in unilateral cochlear implant patients with unilateral deafness and tinnitus

Hear Res. 2008 Nov;245(1-2):98-106. doi: 10.1016/j.heares.2008.09.003. Epub 2008 Sep 12.

Abstract

In cochlear implants, the signal is filtered into different frequency bands and transmitted to electrodes along the cochlea. In this study the frequency-place function for electric hearing was investigated as a means to possibly improve speech coding by delivering information to the appropriate cochlear place. Fourteen subjects with functional hearing in the contralateral ear have been provided with a MED-EL cochlear implant in the deaf ear in order to reduce intractable tinnitus. Pitch scaling experiments were performed using single-electrode, constant-amplitude, constant-rate stimuli in the implanted ear, and acoustic sinusoids in the contralateral ear. The frequency-place function was calculated using the electrode position in the cochlea as obtained from postoperative skull radiographs. Individual frequency-place functions were compared to Greenwood's function in normal hearing. Electric stimulation elicited a low pitch in the apical region of the cochlea, and shifting the stimulating electrode towards the basal region elicited increasingly higher pitch. The frequency-place function did not show a significant shift relative to Greenwood's function. In cochlear implant patients with functional hearing in the non-implanted ear, electrical stimulation produced a frequency-place function that on average resembles Greenwood's function. These results differ from previously derived data.

Publication types

  • Evaluation Study

MeSH terms

  • Acoustic Stimulation
  • Adult
  • Aged
  • Cochlea / diagnostic imaging
  • Cochlear Implants* / statistics & numerical data
  • Deafness / complications*
  • Deafness / physiopathology
  • Deafness / therapy*
  • Electric Stimulation
  • Hearing Loss, Sensorineural / complications
  • Hearing Loss, Sensorineural / physiopathology
  • Hearing Loss, Sensorineural / therapy
  • Humans
  • Loudness Perception
  • Middle Aged
  • Pitch Perception
  • Radiography
  • Signal Processing, Computer-Assisted
  • Tinnitus / etiology*
  • Tinnitus / physiopathology
  • Tinnitus / therapy*
  • Young Adult