Auditory neural tracking reflects target enhancement but not distractor suppression in a psychophysically augmented continuous-speech paradigm

Summary

Selective attention modulates the neural tracking of speech in auditory cortical regions. It is unclear whether this attention modulation is dominated by enhanced target tracking, or suppression of distraction. To settle this long-standing debate, we here employed an augmented electroencephalography (EEG) speech-tracking paradigm with target, distractor, and neutral streams. Concurrent target speech and distractor (i.e., sometimes relevant) speech were juxtaposed with a third, never task-relevant speech stream serving as neutral baseline. Listeners had to detect short target repeats and committed more false alarms originating from the distractor than the neutral stream. Speech tracking revealed target enhancement but no distractor suppression below the neutral baseline. Speech tracking of the target (not distractor or neutral speech) explained single-trial accuracy in repeat detection. In sum, the enhanced neural representation of target speech is specific to processes of attentional gain for behaviourally relevant target speech rather than neural suppression of distraction.