title: Within- and across-channel gap detection in cochlear implant listeners.
abstract: This study examined within- and across-electrode-channel processing of temporal gaps in successful users of MED-EL COMBI 40+ cochlear implants. The first experiment tested across-ear gap duration discrimination (GDD) in four listeners with bilateral implants. The results demonstrated that across-ear GDD thresholds are elevated relative to monaural, within-electrode-channel thresholds; the size of the threshold shift was approximately the same as for monaural, across-electrode-channel configurations. Experiment 1 also demonstrated a decline in GDD performance for channel-asymmetric markers. The second experiment tested the effect of envelope fluctuation on gap detection (GD) for monaural markers carried on a single electrode channel. Results from five cochlear implant listeners indicated that envelopes associated with 50-Hz wide bands of noise resulted in poorer GD thresholds than envelopes associated with 300-Hz wide bands of noise. In both cases GD thresholds improved when envelope fluctuations were compressed by an exponent of 0.2. The results of both experiments parallel those found for acoustic hearing, therefore suggesting that temporal processing of gaps is largely limited by factors central to the cochlea.
authors.affiliation: Department of Otolaryngology - Head & Neck Surgery, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-7070, USA. jhg@med.unc.edu
authors.forename: John H
authors.initials: JH
authors.lastname: Grose
authors.forename: Emily
authors.initials: E
authors.lastname: Buss
mesh_terms: D000161:Acoustic Stimulation; D000328:Adult; D000368:Aged; D001307:Auditory Perception; D001309:Auditory Threshold; D003054:Cochlear Implants; D012048:Correction of Hearing Impairment; D005260:Female; D034381:Hearing Loss / Q000503:physiopathology / Q000534:rehabilitation*; D006801:Humans; D008297:Male; D008875:Middle Aged; D019986:Persons with Hearing Disabilities; D013998:Time Perception