Children who receive cochlear implants develop spoken language on a protracted timescale. The home environment facilitates speech-language development, yet it is relatively unknown how the environment differs between children with cochlear implants and typical hearing. We matched eighteen preschoolers with implants (31-65 months) to two groups of children with typical hearing: by chronological age and hearing age. Each child completed a long-form, naturalistic audio recording of their home environment (appx. 16 hours/child; >730 hours of observation) to measure adult speech input, child vocal productivity, and caregiver-child interaction. Results showed that children with cochlear implants and typical hearing were exposed to and engaged in similar amounts of spoken language with caregivers. However, the home environment did not reflect developmental stages as closely for children with implants, or predict their speech outcomes as strongly. Home-based speech-language interventions should focus on the unique input-outcome relationships for this group of children with hearing loss.

Language mixing is a common feature of many bilingually-raised children's input. Yet how it is related to their language development remains an open question. The current study investigated mixed-language input indexed by observed (30-second segment) counts and proportions in day-long recordings as well as parent-reported scores, in relation to infant vocal activeness (i.e., volubility) when infants were 10 and 18 months old. Results suggested infants who received a higher score or proportion of mixed input in one-on-one social contexts were less voluble. However, within contexts involving language mixing, infants who heard more words were also the ones who produced more vocalizations. These divergent associations between mixed input and infant vocal development point for a need to better understand the causal factors that drive these associations.

Parental input is considered a key predictor of language achievement during the first years of life, yet relatively few studies have assessed its effects on longer-term outcomes. We assess the effects of parental quantity of speech, use of parentese (the acoustically exaggerated, clear, and higher-pitched speech), and turn-taking in infancy, on child language at 5 years. Using a longitudinal dataset of daylong LENA recordings collected with the same group of English-speaking infants (N=44) at 6, 10, 14, 18, 24 months and then again at 5 years, we demonstrate that parents’ consistent (defined as stable and high) use of parentese in infancy was a potent predictor of lexical diversity, mean length of utterance, and frequency of conversational turn-taking between children and adults at Kindergarten entry. Together, these findings highlight the potential importance of a high-quality language learning environment in infancy for success at the start of formal schooling.

Many children grow up hearing multiple languages, learning words in each. How does the number of languages being learned affect multilinguals’ vocabulary development? In a pre-registered study, we compared productive vocabularies of bilingual (n = 170) and trilingual (n = 20) toddlers aged 17–33 months growing up in a bilingual community where both French and English are spoken. We hypothesized that because trilinguals have reduced input in French and English due to time spent hearing their third language, they would have smaller French–English vocabulary sizes than bilinguals. Trilinguals produced on average 2/3 of the number of words in these languages that bilinguals did: however, this difference was not statistically robust due to large levels of variability. Follow-up analyses did, however, indicate a relationship between input quantity and vocabulary size. Our results indicate that similar factors contribute to vocabulary development across toddlers regardless of the number of languages being acquired.

Researchers agree that early literacy activities, like book sharing and parent-child play, are important for stimulating language development. We hypothesize that book sharing is most powerful because it elicits more interactive talk in young children than other activities. Parents of 43 infants (9–18 months) made two daylong audio recordings using the LENA system. We compared a typical day, with spontaneous occurring activities, with an instructed day when caregivers were prompted to do book reading and toy play. Book sharing resulted in a combination of more parent talk, child talk, and interactions than other language activities. Research context did not influence outcomes: no differences were found in language use between the spontaneous and the instructed activities. Overall it seems clear that even with infants shared reading is a strong unique stimulator of language use from parent and child.

We examined the functions of mothers’ speech to infants during two tasks – book-sharing and bead-stringing – in low-income, ethnically diverse families. Mexican, Dominican, and African American mothers and their infants were video-recorded sharing wordless books and toy beads in the home when infants were aged 1;2 and 2;0. Mothers’ utterances were classified into seven categories (labels/descriptions, emotion/state language, attention directives, action directives, prohibitions, questions, and vocal elicitations) which were grouped into three broad language functions: referential language, regulatory language, and vocalization prompts. Mothers’ ethnicity, years of education, years living in the United States, and infant sex and age related to mothers’ language functions. Dominican and Mexican mothers were more likely to use regulatory language than were African American mothers, and African American mothers were more likely to use vocalization prompts than were Latina mothers. Vocalization prompts and referential language increased with mothers’ education and Latina mothers’ years living in the United States. Finally, mothers of boys used more regulatory language than did mothers of girls. Socio-cultural and developmental contexts shape the pragmatics of mothers’ language to infants.

What is the function of babbling in language learning? We examined the structure of parental speech as a function of contingency on infants’ non-cry prelinguistic vocalizations. We analyzed several acoustic and linguistic measures of caregivers’ speech. Contingent speech was less lexically diverse and shorter in utterance length than non-contingent speech. We also found that the lexical diversity of contingent parental speech only predicted infant vocal maturity. These findings illustrate a new form of influence infants have over their ambient language in everyday learning environments. By vocalizing, infants catalyze the production of simplified, more easily learnable language from caregivers.

Before bilingual children can say anything, they must learn to distinguish between the two languages that are spoken to them, and they must learn to make useful perceptual distinctions in each of them in order to understand what is said to them. Conversational interaction and non-verbal communication, such as pointing and gaze, aid children in attending to and processing aspects of their “language input environment” (De Houwer, 2009, 2011), “exposure” in Carroll's terms. As Carroll points out, children must build up their linguistic categories based on their intrinsically category-free “exposure”: they must process speech to acquire language. This reminds me of Wijnen's (2000) notion of language intake, which is the “data base children use to derive hypotheses on the structure of the target grammar” (p. 174), and which constitutes children's selection from what I will continue to call input, pace Carroll.

The current longitudinal study investigated the role of home language and outside home exposure in the development of Dutch and Frisian vocabulary by young bilinguals. Frisian is a minority language spoken in the north of the Netherlands. In three successive test rounds, 91 preschoolers were tested in receptive and productive vocabulary in both languages. Results showed a home language effect for Frisian receptive and productive vocabulary, and Dutch productive vocabulary, but not for Dutch receptive vocabulary. As for outside home exposure, an effect was found on the receptive vocabulary tests only. The results can be explained by the amount of L2-input that participants received. The Dutch input is higher for participants with Frisian as home language compared to the Frisian input for participants with Dutch as home language. The conclusions lead to further implications for language professionals working in language minority contexts.

This paper contributes to current investigations of the nature of babbling in infants raised bilingually by analyzing the babbling of a child raised in a Spanish–English environment. Examination of syllable structure shows the expected preponderance of open syllables in both language contexts while other phenomena point to important differences dependent on language context. While some of the differences relate to general features of the input languages, others coincide with individual features of the parents’ input. These results offer some evidence of distinct babbling according to language context and suggest a possible influence of the type of input.