EEG responses to onset-edge and steady-state segments of continuous speech under selective auditory attention...

Electroencephalography (EEG) signals provide valuable insights into the neural mechanisms of speech perception. However, it still remains unclear how neural responses dynamically align with continuous speech under selective attention modulation in the complex auditory environments. This study examined the evoked and induced EEG responses, their correlations with speech features, and cortical distributions for the target and ignored speech in two-talker competing scenarios. Results showed that selective attention increased the evoked EEG power for the target speech compared to the ignored speech. In contrast, the induced power indicated no significant differences. Low-frequency EEG power and phase responses reliably indexed the target speech identification amid competing streams. Cortical distribution analyses revealed that the evoked power differences between the target and ignored speech were concentrated in the central and parietal cortices. Significant induced power differences between the target and ignored speech presented only at the onset-edge segments in the left temporal cortex. Comparisons between onset-edge and steady-state segments showed the evoked power differences in the right central and temporal cortices and the induced power differences in the frontal cortex for the ignored speech. No significant differences of the cortical distribution were observed between the onset-edge and steady-state segments for the target speech. These findings underscore the distinct contributions of the evoked and induced neural activities and their cortical distributions to selective auditory attention and segment-specific speech perception.