Is neural speech tracking true oscillatory entrainment or evoked responses?

Establish whether low-frequency neural tracking of attended speech in human auditory cortex represents genuine oscillatory entrainment or is better explained by a succession of evoked responses to acoustic edge events or linguistically defined boundaries.

Background

Enhancements of speech tracking with attention are well-documented, but whether they reflect entrainment of endogenous oscillations remains debated. An evoked-response account posits that tracking arises from stereotyped responses to acoustic edges or linguistic boundaries.

Resolving this issue will clarify mechanistic interpretations of a central signature of auditory attention and guide methodological approaches to dissociate oscillatory from evoked contributions.

References

Here, an important caveat is that speech tracking and its attentional modulations are not easily proven to be true neural oscillatory phenomena but likely involve a series of stereotypical, evoked responses to acoustically present 'edge' events or linguistically imposed segmental or phrasal boundaries (e.g., (Oganian et al., 2023). This is an open issue awaiting to be resolved (also see section above, section 1.1b).

— Brain rhythms in cognition -- controversies and future directions  (2507.15639 - Keitel et al., 21 Jul 2025) in Section 2.1.b Auditory attention

Both datasets play the audio through in-ear phones close to the electrodes, and an electrical leak of the sound into the recording is the classic zero-delay artifact; MAESTRO plays it through loudspeakers across a room, and there the check passes. We think this is the most likely explanation, but we have not shown it, and we do not count the KU~Leuven or DTU accuracies as brain decoding.

— Merit: Making every modality earn its contribution in multimodal attention decoding  (2610.17507 - Alavi et al., 13 Oct 2026) in Appendix, Section “The coupling branch on two other datasets,” paragraph “But the direction-in-time check does not confirm it is the brain”