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DOI: 10.3766/jaaa.24.3.3
Electrophysiological Evidence of Augmented Interaural Asymmetry in Middle-Aged Listeners
Publication History
Publication Date:
06 August 2020 (online)
Background: Various dimensions of auditory processing, especially the perception of speech in the presence of background competition, have been shown to deteriorate with age. A persistent problem in the assessment of these age-related changes has been the high prevalence of age-related high-frequency hearing loss in elderly persons. Some investigators have suggested that a more fruitful approach to the study of age-related decline might be to study middle-aged, rather than elderly, persons, where confounding high-frequency hearing loss is less prevalent.
Purpose: To determine whether an increase in the left-ear disadvantage (LED) in dichotic listening could be demonstrated in a group of middle-aged persons.
Research Design: The N400 component of the auditory event-related potential (AERP) was utilized to evaluate interaural asymmetry in a quasi-dichotic competing speech task. Electrophysiological responses were obtained on a word-pair semantic categorization task presented through a front loudspeaker while the listener ignored competing speech presented through either left (competition left [CL]) or right (competition right [CR]) loudspeakers.
Study Samples: Twenty young (18–24 yr) and 20 middle-aged (44–57 yr) females with normal hearing sensitivity.
Data Collection and Analysis: Individual, as well as grand-averaged, AERP waveforms and scalp topographies were analyzed for the word pairs. Peak amplitude and latency measures of the N400 component were subjected to a mixed design analysis of variance (ANOVA).
Results: No significant interaural asymmetry was found in the AERP waveform for the reference word condition in either age group. In response to the second word of the pair, however, middle-aged females showed significantly greater N400 negativity in the CR condition than in the CL condition. No significant laterality effect was found in the young females.
Conclusions: The study of young versus middle-aged participants may be an effective way of avoiding the confound of high-frequency hearing loss in elderly persons when studying age effects on auditory processing.