EEG shows brain can simultaneous encode two speech streams
A new study using EEG recordings reveals that the human brain can simultaneously encode two speech streams during attention switching. The research suggests that the brain performs a transient overlap in processing when shifting focus, which is linked to cognitive effort and lexical context updates.
Why it matters
Understanding these neural mechanisms provides insights into how humans process complex auditory environments and could inform future brain-computer interface development.
Successful speech communication in multi-talker scenarios requires a skillful combination of sustained attention and rapid attention switching. While the neurophysiology literature offers detailed insights into the neural underpinnings of sustained attention, there remains considerable uncertainty on how attention switching takes place. In this study, using EEG recordings from normal-hearing adults in an immersive multi-talker environment, we measured the neural encoding of two competing speech streams amid background babble. Participants were cued to switch attention between streams every 15–30 s. Neural tracking was assessed via Temporal Response Functions (TRF), confirming reliable decoding of attentional focus. Our results indicate asymmetric disengagement and engagement processes during attention switches, where the neural tracking of the new target stream emerges before disengaging from the previous target, revealing a transient simultaneous encoding of two speech streams.
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