Acoustic Cues to Grammatical Structure in Infant-Directed Speech: Cross-Linguistic Evidence

Abstract

Several theorists have suggested that infants use prosodic cues such as pauses, final lengthening, and pitch changes to identify linguistic units in speech. One potential difficulty with this proposal, however, is that the acoustic shape of an utterance is affected by many factors other than its syntax, including its phonetic, lexical, and discourse structure. This has raised questions about how the infant could use timing and pitch as cues to any aspect of linguistic structure without simultaneously factoring out other effects. Acoustic analyses of connected samples of spontaneous speech addressed to 13.5-14-month-old infants by American English- and by Japanese-speaking mothers revealed that both utterance- and phrase-level acoustic regularities were large enough to be detected in spontaneous speech without correcting for other influences on the same acoustic features. (1) Utterance-final vowels were lengthened and underwent exaggerated pitch changes in both languages, and (2) local acoustic changes in duration (English) or pitch (Japanese) were reliably associated with some phrase boundaries within utterances. These findings suggest that a naive listener could estimate a rough prosodic template for each language based on robust acoustic patterns in observed sentences. We discuss ways in which the learner could combine acoustic and distributional analyses across utterances to acquire language-specific variations in prosodic bracketing cues and to obtain indirect perceptual evidence for the internal structure of utterances.

Acoustical cues and grammatical units in speech to two preverbal infants

“…Our acoustic analyses, like those of Fisher & Tokura (1996a) with older infants, found evidence that the acoustical properties of the boundaries between subjects and predicates differ from those of phrase-internal wordlevel boundaries. If we consider these acoustical properties across all sentence types, the cues appear weak and unreliable.…”

Diminutives in child-directed speech supplement metric with distributional word segmentation cues

“…Indeed, similar word segmentation experiments with materials that simulate the structure of Russian diminutives corroborate the ending invariance effect (Kempe, Brooks, & Gillis, 2003). Together with the benefits of CDS in the acquisition of phonology (Kuhl et al, 1997), morphology Kempe, Brooks, Mironova, & Fedorova, 2003), syntax (Fisher & Tokura, 1996), and vocabulary (Golinkoff & Alioto, 1995), this provides yet another example of how this speech register appears to be exquisitely tailored to the task of language learning. …”

Infants' Listening Preferences: Baby Talk or Happy Talk?

“…Several theorists have emphasized the adaptive significance of BT (Fernald, 1992;Fisher & Tokura, 1996;McLeod, 1993;Papoušek et al, 1990;Sachs, 1977). In her summary of this literature, Fernald (1989) enumerated three functional roles of BT.…”

“…When infants are confronted with the task of identifying relevant units in the speech stream, they may exploit prosodic regularities that serve as markers for syntactic constituents (e.g., Kemler-Nelson, Hirsh-Pasek, Jusczyk, & Wright-Cassidy, 1989). For example, mothers lengthen vowel durations to mark phrase boundaries (Morgan, 1986), and cross-linguistic evidence for acoustic cues to syntactic structure in BT (Fisher & Tokura, 1996) implicates language-general markers for large-scale syntactic units. BT may also assist identification of novel words, as Golinkoff and Alioto (1995) showed.…”