title: Detection and rate discrimination of amplitude modulation in electrical hearing.
abstract: Three experiments were designed to examine temporal envelope processing by cochlear implant (CI) listeners. In experiment 1, the hypothesis that listeners' modulation sensitivity would in part determine their ability to discriminate between temporal modulation rates was examined. Temporal modulation transfer functions (TMTFs) obtained in an amplitude modulation detection (AMD) task were compared to threshold functions obtained in an amplitude modulation rate discrimination (AMRD) task. Statistically significant nonlinear correlations were observed between the two measures. In experiment 2, results of loudness-balancing showed small increases in the loudness of modulated over unmodulated stimuli beyond a modulation depth of 16%. Results of experiment 3 indicated small but statistically significant effects of level-roving on the overall gain of the TMTF, but no impact of level-roving on the average shape of the TMTF across subjects. This suggested that level-roving simply increased the task difficulty for most listeners, but did not indicate increased use of intensity cues under more challenging conditions. Data obtained with one subject, however, suggested that the most sensitive listeners may derive some benefit from intensity cues in these tasks. Overall, results indicated that intensity cues did not play an important role in temporal envelope processing by the average CI listener.
authors: Cochlear Implants and Psychophysics Laboratory, Department of Hearing and Speech Sciences, University of Maryland, College Park, Maryland 20742, USA. mchatterjee@hesp.umd.edu
authors: Monita
authors: M
authors: Chatterjee
authors: Cherish
authors: C
authors: Oberzut
mesh_terms: D000161:Acoustic Stimulation; D000328:Adult; D000368:Aged; D001299:Audiometry; D001307:Auditory Perception; D001309:Auditory Threshold; D019929:Cochlear Implantation / Q000295:instrumentation*; D003054:Cochlear Implants; D012048:Correction of Hearing Impairment / Q000523:psychology*; D003463:Cues; D004192:Discrimination, Psychological; D004558:Electric Stimulation; D005260:Female; D006801:Humans; D008144:Loudness Perception; D008297:Male; D008875:Middle Aged; D017711:Nonlinear Dynamics; D019986:Persons with Hearing Disabilities / Q000523:psychology / Q000534:rehabilitation*; D017603:Signal Detection, Psychological; D012815:Signal Processing, Computer-Assisted; D013997:Time Factors; D055815:Young Adult