Exposure to a second language in infancy alters speech production

Effects of multilingualism on Australian infants' language environments in early childhood education centers

This study investigates differences in the language environments experienced by multilingual and monolingual infants in early childhood education and care (ECEC) settings. The Language Environment Analysis (LENA) technology was used to collect day-long audio-recordings from 181 one-year-old infants (age range from 12 to 21 months). We examined whether infants' multilingual status predicts the amount of educators' language input (adult word count, AWC), child vocalizations (CVC) and conversational turns (CTC), as well as interaction effects on AWC, CVC and CTC of infants' multilingual status and other infant, home and ECEC characteristics. Multilevel mixed effects models revealed no main effect of infants' multilingual status on the language environment outcome variables. Instead, infant gender significantly predicted adult word count, with female infants hearing more words from educators than male infants. There was a significant interaction effect between the infants' multilingual status and both their age and length of time in an ECEC setting on child vocalizations. While monolingual infants produced more vocalizations as their age increased, multilingual infants did not show this increase in vocalizations with age. Further, the difference between monolingual and multilingual children's vocalizations decreased as the length of time in ECEC increased. There were no significant predictors of conversational turns. Findings from this study suggest that early childhood educators do not adjust their talk according to the multilingual status of the infants. However, multilingual infants do not increase their vocalizations as their age increases to the same extent as do their monolingual peers. The interaction effect between multilingualism and the length of ECEC attendance also implies that ECEC environments may be particularly beneficial for supporting multilingual infants' vocalizations. This study highlights the need to provide pedagogical support to educators to help them to encourage multilingual infants' vocalizations in ECEC settings.

Setting the Stage for Speech Production: Infants Prefer Listening to Speech Sounds With Infant Vocal Resonances

PURPOSE

Current models of speech development argue for an early link between speech production and perception in infants. Recent data show that young infants (at 4-6 months) preferentially attend to speech sounds (vowels) with infant vocal properties compared to those with adult vocal properties, suggesting the presence of special "memory banks" for one's own nascent speech-like productions. This study investigated whether the vocal resonances (formants) of the infant vocal tract are sufficient to elicit this preference and whether this perceptual bias changes with age and emerging vocal production skills.

METHOD

We selectively manipulated the fundamental frequency (f₀ ) of vowels synthesized with formants specifying either an infant or adult vocal tract, and then tested the effects of those manipulations on the listening preferences of infants who were slightly older than those previously tested (at 6-8 months).

RESULTS

Unlike findings with younger infants (at 4-6 months), slightly older infants in Experiment 1 displayed a robust preference for vowels with infant formants over adult formants when f₀ was matched. The strength of this preference was also positively correlated with age among infants between 4 and 8 months. In Experiment 2, this preference favoring infant over adult formants was maintained when f₀ values were modulated.

CONCLUSIONS

Infants between 6 and 8 months of age displayed a robust and distinct preference for speech with resonances specifying a vocal tract that is similar in size and length to their own. This finding, together with data indicating that this preference is not present in younger infants and appears to increase with age, suggests that nascent knowledge of the motor schema of the vocal tract may play a role in shaping this perceptual bias, lending support to current models of speech development.

SUPPLEMENTAL MATERIAL

https://doi.org/10.23641/asha.17131805.