title: Hierarchical organization in the temporal structure of infant-direct speech and song.
abstract: Caregivers alter the temporal structure of their utterances when talking and singing to infants compared with adult communication. The present study tested whether temporal variability in infant-directed registers serves to emphasize the hierarchical temporal structure of speech. Fifteen German-speaking mothers sang a play song and told a story to their 6-months-old infants, or to an adult. Recordings were analyzed using a recently developed method that determines the degree of nested clustering of temporal events in speech. Events were defined as peaks in the amplitude envelope, and clusters of various sizes related to periods of acoustic speech energy at varying timescales. Infant-directed speech and song clearly showed greater event clustering compared with adult-directed registers, at multiple timescales of hundreds of milliseconds to tens of seconds. We discuss the relation of this newly discovered acoustic property to temporal variability in linguistic units and its potential implications for parent-infant communication and infants learning the hierarchical structures of speech and language.
authors.affiliation: Ludwig-Maximilians-University, Munich, Germany; Laboratoire Parole et Langage, UMR 7309, CNRS / Aix-Marseille University, Aix-en-Provence, France; Laboratoire Phonétique et Phonologie, UMR 7018, CNRS / Université Sorbonne Nouvelle Paris-3, Paris, France. Electronic address: simone.falk@univ-paris3.fr.
authors.forename: Simone
authors.initials: S
authors.lastname: Falk
authors.affiliation: University of California, Merced, USA.
authors.forename: Christopher T
authors.initials: CT
authors.lastname: Kello
mesh_terms: D000328:Adult; D016000:Cluster Analysis; D005260:Female; D006801:Humans; D007223:Infant; D008297:Male; D009034:Mother-Child Relations; D010700:Phonetics; D012815:Signal Processing, Computer-Assisted; D063346:Singing; D013060:Speech; D013061:Speech Acoustics; D013997:Time Factors
keywords: Hierarchical nested clustering; Infant-directed communication; Language development; Speech and song; Temporal variability