title: The integration of laughter and speech in vocal communication: a dynamic systems perspective.
abstract: Laughter in infant-directed speech was examined in 13 mother-infant pairs to investigate the possible co-occurrence of speech and laughter. Contrary to previous findings in adult-adult social interaction, all mothers produced speech simultaneously with laughter in up to 50% of laughs. In most of these speech-laughs the onset of laugh and speech was simultaneous. Laughter occurred on both function and content words and was more likely to occur on approximately 2 words and on utterances that were statements rather than questions or exclamations. Laughter and speech are different outcomes produced from a reorganization of the same vocal/anatomical parameters. A 3rd outcome is possible in the form of speech-laughs utilizing features from both laughter and speech. In speech-laughs, the duration of the vocalization was more likely to increase, and the changes in the utterance were likely to include 1 or more of the features of vowel elongation, syllabic pulsation, breathiness, and pitch change. These findings and individual variations in the resulting vocal output are discussed from a dynamic systems perspective. It is argued that neither speech nor laughter is dominant when both are combined, but that this is a more complex vocal outcome produced with idiosyncratic flexibility within stable temporal and physiological constraints.
authors.affiliation: Richardson Development Center for Children, Dallas, TX, USA. enwokah@aol.com
authors.forename: E E
authors.initials: EE
authors.lastname: Nwokah
authors.forename: H C
authors.initials: HC
authors.lastname: Hsu
authors.forename: P
authors.initials: P
authors.lastname: Davies
authors.forename: A
authors.initials: A
authors.lastname: Fogel
mesh_terms: D003142:Communication; D005260:Female; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D007845:Laughter / Q000502:physiology*; D008297:Male; D009034:Mother-Child Relations; D013060:Speech / Q000502:physiology*; D013061:Speech Acoustics; D013997:Time Factors; D014831:Voice / Q000502:physiology*