Acoustic Determinants of Infant Preference for Motherese Speech

Three experiments investigated possible acoustic determinants of the infant listening preference for motherese speech found by Fernald (1985). To test the hypothesis that the intonation of motherese speech was sufficient to elicit this preference, it was necessary to eliminate lexical content and to isolate the three maior acoustic correlates of intonation: (1) fundamental frequency (Fo), or pitch: (2) amplitude, correlated with loudness; and (3) duration, related to speech rhythm. Three sets of auditory reinforcers were computer-synthesized, derived from the FO (Experiment 1). amplitude (Experiment 2). and durotion (Experiment 3) characteristics of the infantand adult-directed natural speech samples used by Fernald (1985). Thus, each of these experiments focused on particular prosodic variables in the absence of segmental variation. Twenty 4-month-old infants were tested in on operant ouditory preference procedure in each experiment. Infonts showed a significant preference for the FO-patterns of motherese speech, but not for the amplitude or duration patterns of motherese.