title: Neural tonotopy in cochlear implants: an evaluation in unilateral cochlear implant patients with unilateral deafness and tinnitus.
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.
authors.affiliation: C. Doppler Laboratory for Active Implantable Systems, Institute of Ion Physics and Applied Physics, University of Innsbruck, Innsbruck, Austria. katrien.vermeire@uibk.ac.at
authors.forename: Katrien
authors.initials: K
authors.lastname: Vermeire
authors.forename: Andrea
authors.initials: A
authors.lastname: Nobbe
authors.forename: Peter
authors.initials: P
authors.lastname: Schleich
authors.forename: Peter
authors.initials: P
authors.lastname: Nopp
authors.forename: Maurits H
authors.initials: MH
authors.lastname: Voormolen
authors.forename: Paul H
authors.initials: PH
authors.lastname: Van de Heyning
mesh_terms: D000161:Acoustic Stimulation; D000328:Adult; D000368:Aged; D003051:Cochlea / Q000000981:diagnostic imaging; D003054:Cochlear Implants / Q000706:statistics & numerical data; D003638:Deafness / Q000150:complications* / Q000503:physiopathology / Q000628:therapy*; D004558:Electric Stimulation; D006319:Hearing Loss, Sensorineural / Q000150:complications / Q000503:physiopathology / Q000628:therapy; D006801:Humans; D008144:Loudness Perception; D008875:Middle Aged; D010898:Pitch Perception; D011859:Radiography; D012815:Signal Processing, Computer-Assisted; D014012:Tinnitus / Q000209:etiology* / Q000503:physiopathology / Q000628:therapy*; D055815:Young Adult