Neural indices of spoken word processing in background multi-talker babble.

OBJECTIVE To evaluate the impact of multi-talker babble on cortical event-related potentials (ERPs), specifically the N400, in a spoken semantic priming paradigm. DESIGN Participants listened in quiet and with background babble to word triplets, evaluating whether the third word was related to the preceding words. A temporo-spatial principal component analysis was conducted on ERPs to the first and second words (S1 and S2), processed without an overt behavioral response. One factor corresponded to the N400 and revealed greater processing negativity for unrelated as compared to related S2s in quiet and in babble. STUDY SAMPLE Twelve young adults with normal hearing. RESULTS Background babble had no significant impact on the N400 in the posterior region but increased neural processing negativity at anterior and central regions during the same timeframe. This differential processing negativity in babble occurred in response to S2 but not S1. Furthermore, background babble impacted processing negativity for related S2s more than unrelated S2s. CONCLUSIONS Results suggest that speech processing in a modestly degraded listening environment alters neural activity associated with auditory working memory, attention, and semantic processing in anterior and central scalp regions.