The temporal structure of speech provides crucial information to listeners for comprehension: In particular, the slow modulations in the amplitude envelope constitute important landmarks to discretize the continuous signal into linguistic units. Contemporary models of speech perception attribute a major functional role to brain rhythmic activity in this process: By aligning their phase to the quasi-periodic patterns in speech, neural oscillations would facilitate speech decoding. We here review evidence from EEG/MEG studies showing neural theta-range (~4–8 Hz) tracking of syllabic rhythm, with a special interest in speech rate variations. We also discuss to what extent neural oscillatory coupling contributes to, and is in turn modulated by, speech intelligibility, namely whether it is only acoustically or also linguistically guided. We finally review some findings showing that in addition to auditory cortex, motor regions play an active role in the oscillatory dynamic underlying speech processing.

Recent studies have shown that neural activity tracks the syntactic structure of phrases and sentences in connected speech. This work has sparked intense debate, with some researchers aiming to account for the effect in terms of the overt or imposed prosodic properties of the speech signal. In this chapter, we present four types of arguments against attempts to explain putatively syntactic tracking effects in prosodic terms. The most important limitation of such prosodic accounts is that they are architecturally incomplete, as prosodic information does not arise in speech autonomously. Prosodic and syntactic structure are interrelated, so prosodic cues are informative about the intended syntactic analysis, and syntactic information can be used to aid speech perception. Rather than trying to attribute neural tracking effects exclusively to one linguistic component, we consider it more fruitful to think about ways in which the interaction between the components drives the neural signal.