Acoustic typology of infant pre‐ and post‐linguistic protosyllables

Abstract

Three hundred quasisyllabic utterances were excerpted from the vocalizations of three infants at monthly intervals in the 4‐ to 14th‐month epoch of development. Samples were recorded while at play with the mother in a toy‐filled, sound‐treated chamber. F1, F2, f0, and I0, trajectories for the entire quasisyllable were extracted from digital FFT/waveform displays. Syllable, consonant, vowel and transition durations, formant and I0 envelope velocities, and jitter ad shimmer measurement were made. Natural‐class transcriptions and articulatory “well‐formedness” evaluations were made for each utterance. A behavioral analysis checklist was available for each utterance. Analysis revealed that even perceptually labelable seemingly unexceptional tokens displayed combinations of nonadult‐like acoustic parameters. Tokens were sorted by clusters of variables into a typology of emergent syllabic forms based upon adult and nonadult‐like values of the classificatory acoustic‐perceptual variables. The syllable well‐formedness related complexly to the infant's attributed intent to communicate. The prelinguistic utterances were considerably more “juvenile” acoustically than perception would lead one to believe.