Utterance Duration as It Relates to Communicative Variables in Infant Vocal Development

We aimed to provide novel information on utterance duration as it relates to vocal type, facial affect, gaze direction, and age in the prelinguistic/early linguistic infant.

Infant utterances were analyzed from longitudinal recordings of 15 infants at 8, 10, 12, 14, and 16 months of age. Utterance durations were measured and coded for vocal type (i.e., squeal, growl, raspberry, vowel, cry, laugh), facial affect (i.e., positive, negative, neutral), and gaze direction (i.e., to person, to mirror, or not directed).

Of the 18,236 utterances analyzed, durations were typically shortest at 14 months of age and longest at 16 months of age. Statistically significant changes were observed in utterance durations across age for all variables of interest.

Despite variation in duration of infant utterances, developmental patterns were observed. For these infants, utterance durations appear to become more consolidated later in development, after the 1st year of life. Indeed, 12 months is often noted as the typical age of onset for 1st words and might possibly be a point in time when utterance durations begin to show patterns across communicative variables.