Acoustic challenge and hearing loss induce shifts in predictive and integrative processing during speech comprehension in older listeners: Evidence from event-related brain potentials

When faced with increased processing demands during speech comprehension, (especially older) listeners may compensate for those demands by shifting the cognitive strategies they use. In the current study, older adults with varying hearing acuity (N = 80), listened to highly predictable sentence contexts that ended in either an expected word, an unexpected word, or a morphosyntactic violation of the expected word both in quiet and in background noise. We recorded EEG and extracted event-related potentials (ERPs) to target words. For older adults with normal hearing, we observed a small prediction-related ERP response and a robust P600 response in quiet. In noise, the integration-related P600 response to syntactic violations was reduced while we observed an increased syntactic N400 effect, suggesting a shift from an integrative mode to reliance on lexical predictions. In quiet, a similar shift towards reduced integration and increased prediction was observed with increasing hearing loss, but these prediction-related effects were severely reduced when speech was additionally presented in noise, suggesting compounding auditory limits to compensatory reliance on contextual prediction. Collectively, these results suggest that older listeners show adaptive shifts between integrative and predictive processing modes as a function of acoustic challenge and hearing acuity.