Speech comprehension in noisy environments: Evidence from the predictability effects on the N400 and LPC

Abstract

IntroductionSpeech comprehension involves context-based lexical predictions for efficient semantic integration. This study investigated how noise affects the predictability effect on event-related potentials (ERPs) such as the N400 and late positive component (LPC) in speech comprehension.MethodsTwenty-seven listeners were asked to comprehend sentences in clear and noisy conditions (hereinafter referred to as “clear speech” and “noisy speech,” respectively) that ended with a high-or low-predictability word during electroencephalogram (EEG) recordings.ResultsThe study results regarding clear speech showed the predictability effect on the N400, wherein low-predictability words elicited a larger N400 amplitude than did high-predictability words in the centroparietal and frontocentral regions. Noisy speech showed a reduced and delayed predictability effect on the N400 in the centroparietal regions. Additionally, noisy speech showed a predictability effect on the LPC in the centroparietal regions.DiscussionThese findings suggest that listeners achieve comprehension outcomes through different neural mechanisms according to listening conditions. Noisy speech may be comprehended with a second-pass process that possibly functions to recover the phonological form of degraded speech through phonetic reanalysis or repair, thus compensating for decreased predictive efficiency.

The N270 as an index of consumer commodity color preference in the S1–S2 paradigm

“…The N270 was elicited through a range of stimuli, including shape, color, spatial location, and simple arithmetic tasks ( Bennett et al, 2014 ). This N270 component is the electric signal of the cerebral cortex for processing conflict information, and the component exhibits characteristics analogous to those of other negative ERP components, such as error-related negativity ( Figuracion et al, 2023 ; Meyer et al, 2023 ), mismatch negativity ( Riel et al, 2022 ; Usui et al, 2023 ), and semantic N400 ( Undorf et al, 2020 ; Hsin et al, 2023 ). Therefore, if there is a significant difference in the N270 component between the “Like” trials and the “Dislike” trials, the participants’ assessment of “Like”/ “Dislike” is associated with the consistency between the color of stimulus S2, and the color representation induced by the memory of stimulus S1.…”

Effects of linguistic context and noise type on speech comprehension

“…There is relatively little empirical evidence demonstrating how background noise affects listeners’ ability to generate predictions based on linguistic context. Evidence from electroencephalography (EEG) suggests that background noise disrupts listeners’ ability to generate predictions: brain wave responses to unexpected semantic input (i.e., N400 effects) tend to be delayed when speech is presented in background noise ( Connolly et al, 1992 ; Silcox and Payne, 2021 ; Hsin et al, 2023 ). On this account, listeners may be less efficient when facing greater perceptual complexity (i.e., acoustic-phonetic similarity) associated with informational masking (e.g., babble noise) as compared to energetic masking (e.g., SSN).…”