title: The mismatch negativity as a measure of auditory stream segregation in a simulated "cocktail-party" scenario: effect of age.
abstract: With age the ability to understand speech in multitalker environments usually deteriorates. The central auditory system has to perceptually segregate and group the acoustic input into sequences of distinct auditory objects. The present study used electrophysiological measures to study effects of age on auditory stream segregation in a multitalker scenario. Younger and older adults were presented with streams of short speech stimuli. When a single target stream was presented, the occurrence of a rare (deviant) syllable among a frequent (standard) syllable elicited the mismatch negativity (MMN), an electrophysiological correlate of automatic deviance detection. The presence of a second, concurrent stream consisting of the deviant syllable of the target stream reduced the MMN amplitude, especially when located nearby the target stream. The decrease in MMN amplitude indicates that the rare syllable of the target stream was less perceived as deviant, suggesting reduced stream segregation with decreasing stream distance. Moreover, the presence of a concurrent stream increased the MMN peak latency of the older group but not that of the younger group. The results provide neurophysiological evidence for the effects of concurrent speech on auditory processing in older adults, suggesting that older adults need more time for stream segregation in the presence of concurrent speech.
authors.affiliation: Aging Research Group, Leibniz Research Centre for Working Environment and Human Factors, Technical University of Dortmund (IfADo), Dortmund, Germany. Electronic address: getzmann@ifado.de.
authors.forename: Stephan
authors.initials: S
authors.lastname: Getzmann
authors.affiliation: Department of Psychology, Cognitive Brain Research Unit, University of Helsinki, Helsinki, Finland; Institute of Psychology, University of Tartu, Tartu, Estonia; Center of Functionally Integrative Neuroscience (CFIN), University of Aarhus, Aarhus, Denmark.
authors.forename: Risto
authors.initials: R
authors.lastname: Näätänen
mesh_terms: D000161:Acoustic Stimulation; D000328:Adult; D000368:Aged; D000375:Aging / Q000502:physiology*; D001303:Auditory Cortex / Q000502:physiology*; D001306:Auditory Pathways / Q000502:physiology; D001309:Auditory Threshold / Q000502:physiology*; D004192:Discrimination, Psychological; D005260:Female; D006801:Humans; D008144:Loudness Perception / Q000502:physiology*; D008297:Male; D008875:Middle Aged; D011930:Reaction Time / Q000502:physiology*; D013067:Speech Perception / Q000502:physiology*; D055815:Young Adult
keywords: Aging; Auditory stream segregation; Mismatch negativity (MMN); Speech perception; “Cocktail-party” scenario