Additive effects of lengthening on the utterance-final word in child-directed speech

Abstract

Purpose: The authors investigated lengthening effects in child-directed speech (CDS) across the sentence, testing the additive effects on duration of Word Position, Register, Focus, and Sentence Mode (statement/question).

Method: Five theater students produced 6 sentences containing 5 monosyllabic words in a simulated dialogue, varying in Register, Focus, and Sentence Mode. The authors segmented a total of 1,800 sentences using forced-alignment tools, and they analyzed the duration of each word.

Results: The results show significant effects of Register, Word Position, and their interactions. The simple effect of Register was significant in all 5 word positions, indicating a global elongation effect in CDS. Interestingly, there was no proportional increase of the final word in CDS. In addition, the 3-way interactions Register × Word Position × Focus and Register × Word Position × Sentence Mode were significant, which converge to the conclusion that the utterance-final word in CDS is additively elongated when it is focused and in a statement.

Conclusion: Elongation in CDS is a global effect, but the additive effects of duration demonstrated in the authors' data suggest that the effect of enhanced utterance-final lengthening in CDS in naturalistic samples may be a by-product of discourse characteristics of CDS.