Intonation Units: Prosodic Regularity in Spontaneous Speech as a Window onto Cognitive Dynamics

Intonation units (IUs) are a fundamental prosodic unit of all known human languages, and as such they likely constitute an absolute universal property of language. IUs are chunks defined by a specific pattern of syllable delivery, together with resets in pitch and articulatory force. In this chapter we discuss IUs from four different perspectives and introduce them within the context of rhythms of speech, language, and the brain. First, we provide a detailed description of how IUs are defined. Second, we review linguistic research on the roles of IUs in communication, including their cross-linguistic applicability. This body of research suggests that IUs provide a universal structural cue for the cognitive dynamics of speech production and comprehension at a timescale of ~1 Hz. Third, we synthesize the linguistic perspective with findings from the study of brain rhythms and cognition. Finally, we review the existing algorithmic tools for IU identification from speech acoustics, to facilitate the incorporation of IUs in experimental and quantitative research.