Concurrent processing of the prosodic hierarchy is supported by cortical entrainment and phase-amplitude coupling

Abstract

Models of phonology posit a hierarchy of prosodic units that are relatively independent from syntactic structure, requiring its own parsing. Surprisingly, it remains unexplored how this prosodic hierarchy is represented in the brain. We investigated this foundational question by means of an EEG study. Thirty young adults listened to German sentences containing manipulations at different levels of the prosodic hierarchy. Evaluating speech-to-brain cortical entrainment and phase-amplitude coupling revealed that prosodys hierarchical structure is maintained at the neural level. The faithfulness of this tracking varied as a function of the hierarchys degree of intactness as well as systematic inter-individual differences in audio-motor synchronization. The results underscore the role of complex oscillatory mechanisms in configuring the continuous and hierarchical nature of the speech signal and firmly situate prosody as a structure indispensable from theoretical perspectives on spoken language comprehension in the brain.