title: On the relationship between auditory cognition and speech intelligibility in cochlear implant users: An ERP study.
abstract: There is a high degree of variability in speech intelligibility outcomes across cochlear-implant (CI) users. To better understand how auditory cognition affects speech intelligibility with the CI, we performed an electroencephalography study in which we examined the relationship between central auditory processing, cognitive abilities, and speech intelligibility. Postlingually deafened CI users (N=13) and matched normal-hearing (NH) listeners (N=13) performed an oddball task with words presented in different background conditions (quiet, stationary noise, modulated noise). Participants had to categorize words as living (targets) or non-living entities (standards). We also assessed participants' working memory (WM) capacity and verbal abilities. For the oddball task, we found lower hit rates and prolonged response times in CI users when compared with NH listeners. Noise-related prolongation of the N1 amplitude was found for all participants. Further, we observed group-specific modulation effects of event-related potentials (ERPs) as a function of background noise. While NH listeners showed stronger noise-related modulation of the N1 latency, CI users revealed enhanced modulation effects of the N2/N4 latency. In general, higher-order processing (N2/N4, P3) was prolonged in CI users in all background conditions when compared with NH listeners. Longer N2/N4 latency in CI users suggests that these individuals have difficulties to map acoustic-phonetic features to lexical representations. These difficulties seem to be increased for speech-in-noise conditions when compared with speech in quiet background. Correlation analyses showed that shorter ERP latencies were related to enhanced speech intelligibility (N1, N2/N4), better lexical fluency (N1), and lower ratings of listening effort (N2/N4) in CI users. In sum, our findings suggest that CI users and NH listeners differ with regards to both the sensory and the higher-order processing of speech in quiet as well as in noisy background conditions. Our results also revealed that verbal abilities are related to speech processing and speech intelligibility in CI users, confirming the view that auditory cognition plays an important role for CI outcome. We conclude that differences in auditory-cognitive processing contribute to the variability in speech performance outcomes observed in CI users.
authors.affiliation: Department of Otolaryngology, Hannover Medical School, Germany; Cluster of Excellence "Hearing4all", Germany. Electronic address: Finke.Mareike@mh-hannover.de.
authors.forename: Mareike
authors.initials: M
authors.lastname: Finke
authors.affiliation: Department of Otolaryngology, Hannover Medical School, Germany; Cluster of Excellence "Hearing4all", Germany.
authors.forename: Andreas
authors.initials: A
authors.lastname: Büchner
authors.affiliation: Cluster of Excellence "Hearing4all", Germany; Department of Dutch, University of Oldenburg, Germany.
authors.forename: Esther
authors.initials: E
authors.lastname: Ruigendijk
authors.affiliation: Neuroplasticity and Learning in the Healthy Aging Brain, Psychological Institute, University of Zurich, Switzerland; Cognitive Psychology Unit (CPU), University of Klagenfurt, Austria.
authors.forename: Martin
authors.initials: M
authors.lastname: Meyer
authors.affiliation: Cluster of Excellence "Hearing4all", Germany; Department of Neurology, Hannover Medical School, Germany; Department of Otorhinolaryngology, University of Cologne, Germany.
authors.forename: Pascale
authors.initials: P
authors.lastname: Sandmann
mesh_terms: D000161:Acoustic Stimulation / Q000379:methods; D000328:Adult; D000368:Aged; D001921:Brain / Q000503:physiopathology*; D003054:Cochlear Implants; D003071:Cognition / Q000502:physiology*; D004569:Electroencephalography; D005071:Evoked Potentials; D005260:Female; D034381:Hearing Loss / Q000503:physiopathology* / Q000534:rehabilitation*; D006801:Humans; D007802:Language; D007807:Language Tests; D008297:Male; D008570:Memory, Short-Term; D008875:Middle Aged; D009483:Neuropsychological Tests; D013063:Speech Discrimination Tests; D013067:Speech Perception / Q000502:physiology*
keywords: Cochlear implant; Electroencephalography; Event-related potentials; Listening effort; Speech intelligibility; Verbal ability