ENDOGENOUS BRAIN RHYTHMS PREDICT INDIVIDUAL DIFFERENCES IN SPEECH COMPREHENSION

Individuals differ widely in their ability to understand speech under challenging conditions. Endogenous brain rhythms, which are ubiquitous neural oscillations that vary across individuals, may shape language processing. Our large-scale study (N = 400, aged 16 to 76) investigates whether resting-state EEG rhythms predict speech comprehension abilities. Participants completed a 10-minute EEG recording and three behavioural speech comprehension tasks: noise-masked, time-compressed, and interrupted speech. By modelling individual peak frequencies and amplitudes, we aimed to disentangle how these rhythms might facilitate comprehension. Initial analyses confirmed broad inter-individual differences in task performance across all tasks, and that task performance was correlated across participants. Electrophysiologically, brain rhythms were organised into topographically distinct patterns, with for example theta being most prominent in central auditory electrodes and alpha being most prominent in occipital electrodes. We found several rhythmic patterns that influenced speech comprehension, particularly at more difficult levels. For example, individual theta peak frequency predicted comprehension in the time-compressed speech task: faster theta rhythm was associated with better comprehension of fast speech, whereas individual theta amplitude was associated with comprehension of noise-masked speech. Interestingly, lower auditory alpha amplitude at rest was associated with better performance across tasks. These findings could inform personalised interventions (e.g., hearing aids tailored to neural profiles) and refine theoretical models of speech perception across populations. Ultimately, our findings suggest that the brain’s rhythmic architecture is a foundational aspect of auditory comprehension, offering a neurophysiological framework to better understand individual variability in communication abilities.