PT  - JOURNAL ARTICLE
AU  - Maya Inbar
AU  - Eitan Grossman
AU  - Ayelet N. Landau
TI  - Sequences of Intonation Units Form a 1 Hz Rhythm
AID  - 10.1101/765016
DP  - 2019 Jan 01
TA  - bioRxiv
PG  - 765016
4099  - http://biorxiv.org/content/early/2019/09/11/765016.short
4100  - http://biorxiv.org/content/early/2019/09/11/765016.full
AB  - Studies of speech processing investigate the relationship between temporal structure in speech stimuli and neural activity (Giraud & Poeppel, 2012; Gross et al., 2013; Park, Ince, Schyns, Thut, & Gross, 2015). The speech envelope, a representation of speech that captures amplitude fluctuations in the acoustic speech signal, has been used to probe this temporal relationship. The envelope is most commonly understood to reflect the succession of syllables at ∼5 Hz (Ding et al., 2017; Greenberg, Carvey, Hitchcock, & Chang, 2003; Räsänen, Doyle, & Frank, 2018; Varnet, Ortiz-Barajas, Erra, Gervain, & Lorenzi, 2017). Despite clear evidence for auditory tracking of the envelope at lower frequencies (Gross et al., 2013; Park et al., 2015), it is not well understood what linguistic information is captured in the speech envelope beyond the syllable level. Here, we harness linguistic theory to focus on Intonation Units (IUs), while analyzing their temporal structure as captured in the speech envelope.IUs are prosodic units (Chafe, 1994; Du Bois, Cumming, Schuetze-Coburn, & Paolino, 1992; Himmelmann, Sandler, Strunk, & Unterladstetter, 2018) which are defined by a specific pattern of syllable delivery, together with resets in pitch and articulatory force. Linguistic studies of spontaneous speech indicate that this prosodic segmentation paces new information in language use across numerous and diverse languages. Therefore, IUs provide an important structural cue for the cognitive dynamics producing and comprehending speech universally.We study the relation between IUs and the periodic components of the speech envelope in six languages. We apply analysis methods from investigations of neural synchronization (Vinck, van Wingerden, Womelsdorf, Fries, & Pennartz, 2010) to study recordings from every-day speech contexts of over 100 speakers. We find that sequences of IUs form a consistent 1 Hz rhythm. Our results demonstrate that IUs form a significant periodic cue within the speech envelope that could be utilized by the cognitive and neural systems when tracking speech.