Sequential stream segregation in normally-hearing and cochlear-implant listeners.
Sequential stream segregation by normal hearing (NH) and cochlear implant (CI) listeners was investigated using an irregular rhythm detection (IRD) task. Pure tones and narrowband noises of different bandwidths were presented monaurally to older and younger NH listeners via headphones. For CI users, stimuli were delivered as pure tones via soundfield and via direct electrical stimulation. Results confirmed that tonal pitch is not essential for stream segregation by NH listeners and that aging does not reduce NH listeners' stream segregation. CI listeners' stream segregation was significantly poorer than NH listeners' with pure tone stimuli. With direct stimulation, however, CI listeners showed significantly stronger stream segregation, with a mean normalized pattern similar to NH listeners, implying that the CI speech processors possibly degraded acoustic cues. CI listeners' performance on an electrode discrimination task indicated that cues that are salient enough to make two electrodes highly discriminable may not be sufficiently salient for stream segregation, and that gap detection/discrimination, which must depend on perceptual electrode differences, did not play a role in the IRD task. Although the IRD task does not encompass all aspects of full stream segregation, these results suggest that some CI listeners may demonstrate aspects of stream segregation.
Department of Hearing and Speech Sciences, University of Maryland, Cochlear Implants and Psychophysics Laboratory, 0100 LeFrak Hall, College Park, Maryland 20742, USA.
Viral D
VD
Tejani
Department of Hearing and Speech Sciences, University of Maryland, Cochlear Implants and Psychophysics Laboratory, 0100 LeFrak Hall, College Park, Maryland 20742, USA.
Kara C
KC
Schvartz-Leyzac
Department of Hearing and Speech Sciences, University of Maryland, Cochlear Implants and Psychophysics Laboratory, 0100 LeFrak Hall, College Park, Maryland 20742, USA.
Monita
M
Chatterjee
D000161:Acoustic Stimulation; D000293:Adolescent; D000328:Adult; D000367:Age Factors; D000368:Aged; D001301:Audiometry, Pure-Tone; D016022:Case-Control Studies; D019929:Cochlear Implantation / Q000295:instrumentation*; D003054:Cochlear Implants; D003463:Cues; D004558:Electric Stimulation; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D019986:Persons with Hearing Disabilities / Q000523:psychology / Q000534:rehabilitation*; D017603:Signal Detection, Psychological; D013067:Speech Perception; D055815:Young Adult