Acoustic determinants of infant preference for motherese speech

Abstract

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 major acoustic correlates of intonation: (1) fundamental frequency (F_o), 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 F_o (Experiment 1), amplitude (Experiment 2), and duration (Experiment 3) characteristics of the infant- and 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 an operant auditory preference procedure in each experiment. Infants showed a significant preference for the F_o-patterns of motherese speech, but not for the amplitude or duration patterns of motherese.