Russian vowels in mothers’ speech to infants and adults

Abstract

Cross-linguistically, when mothers address their infants they produce acoustically more extreme point vowels (/i/, /u/, and /a/) than they produce when speaking to another adult [Kuhl et al., Science 277, 684–686 (1997)]. This study examines three nonpoint vowels in Russian (/e/, /o/, /’i/) and compares their acoustics in infant-directed (ID) and adult-directed (AD) speech with the acoustics of Russian point vowels in AD and ID speech. Six target words containing the nonpoint vowels in stressed syllables were recorded while ten mothers conversed with their infant and another adult. F1, F2, and F0 were measured at vowel onset, center, and offset. As with the point vowels, the acoustic structure of all three vowels differs significantly in ID and AD speech. F2 tends to move to an acoustically more extreme position in each case. In addition, nonpoint ID vowels show more vowel-inherent formant movement across the course of the vowel. Formant movement may provide an important cue to vowel identity, and its exaggeration in ID speech may increase the likelihood that infants incorporate formant movement into their mental representation of a vowel. Significant differences in formant structure were found for vowels in one-, two-, and three-syllable words, including vowels with short mean durations.