title: Limitations on Monaural and Binaural Temporal Processing in Bilateral Cochlear Implant Listeners.
abstract: Monaural rate discrimination and binaural interaural time difference (ITD) discrimination were studied as functions of pulse rate in a group of bilaterally implanted cochlear implant users. Stimuli for the rate discrimination task were pulse trains presented to one electrode, which could be in the apical, middle, or basal part of the array, and in either the left or the right ear. In each two-interval trial, the standard stimulus had a rate of 100, 200, 300, or 500 pulses per second and the signal stimulus had a rate 35% higher. ITD discrimination between pitch-matched electrode pairs was measured for the same standard rates as in the rate discrimination task and with an ITD of +/- 500 μs. Sensitivity (d') on both tasks decreased with increasing rate, as has been reported previously. This study tested the hypothesis that deterioration in performance at high rates occurs for the two tasks due to a common neural basis, specific to the stimulation of each electrode. Results show that ITD scores for different pairs of electrodes correlated with the lower rate discrimination scores for those two electrodes. Statistical analysis, which partialed out overall differences between listeners, electrodes, and rates, supports the hypothesis that monaural and binaural temporal processing limitations are at least partly due to a common mechanism.
authors.affiliation: Department of Biomedical Engineering, New Jersey Institute of Technology, 645 Fenster Hall, 323 Martin Luther King Blvd, Newark, NJ, 07102, USA. ihlefeld@njit.edu.
authors.forename: Antje
authors.initials: A
authors.lastname: Ihlefeld
authors.affiliation: MRC Cognition and Brain Sciences Unit, 15 Chaucer Rd, Cambridge, CB2 7EF, UK. bob.carlyon@mrc-cbu.cam.ac.uk.
authors.forename: Robert P
authors.initials: RP
authors.lastname: Carlyon
authors.affiliation: Waisman Center, 1500 Highland Avenue, Madison, WI, 53705, USA. ahkan@waisman.wisc.edu.
authors.forename: Alan
authors.initials: A
authors.lastname: Kan
authors.affiliation: Waisman Center, 1500 Highland Avenue, Madison, WI, 53705, USA. thchurchill@gmail.com.
authors.forename: Tyler H
authors.initials: TH
authors.lastname: Churchill
authors.affiliation: Waisman Center, 1500 Highland Avenue, Madison, WI, 53705, USA. litovsky@waisman.wisc.edu.
authors.forename: Ruth Y
authors.initials: RY
authors.lastname: Litovsky
mesh_terms: D000328:Adult; D000368:Aged; D003054:Cochlear Implants; D006801:Humans; D008144:Loudness Perception; D008875:Middle Aged; D010897:Pitch Discrimination
keywords: cochlear implant; interaural time difference; pitch; rate sensitivity