Neural Tracking Measures of Speech Intelligibility: Manipulating Intelligibility while Keeping Acoustics Unchanged.

Electrophysiological studies have shown that brain tracks different speech features. How these neural tracking measures are modulated by speech intelligibility, however, remained elusive. Using noise-vocoded speech and a priming paradigm, we disentangled the neural effects of intelligibility from the underlying acoustical confounds. Neural intelligibility effects are analyzed at both acoustic and linguistic level using multivariate Temporal Response Functions. Here, we find evidence for an effect of intelligibility and engagement of top-down mechanisms, but only in responses to lexical structure of the stimuli, suggesting that lexical responses are strong candidates for objective measures of intelligibility. Auditory responses are not influenced by intelligibility but only by the underlying acoustic structure of the stimuli.