Parental language input is one of the best predictors of children's language achievement. Parentese, a near-universal speaking style distinguished by higher pitch, slower tempo, and exaggerated intonation, has been documented in speech directed toward young children in many countries. Previous research shows that the use of parentese and parent-child turn-taking are both associated with advances in children's language learning. We conducted a randomized controlled trial to determine whether a parent coaching intervention delivered when the infants are 6, 10, and 14 mo of age can enhance parental language input and whether this, in turn, changes the trajectory of child language development between 6 and 18 mo of age. Families of typically developing 6-mo-old infants (n = 71) were randomly assigned to intervention and control groups. Naturalistic firstperson audio recordings of the infants' home language environment and vocalizations were recorded when the infants were 6, 10, 14, and 18 mo of age. After the 6-, 10-, and 14-mo recordings, intervention, but not control parents attended individual coaching appointments to receive linguistic feedback, listen to language input in their own recordings, and discuss age-appropriate activities that promote language growth. Intervention significantly enhanced parental use of parentese and parent-child turn-taking between 6 and 18 mo. Increases in both variables were significantly correlated with children's language growth during the same period, and children's language outcomes at 18 mo. Using parentese, a socially and linguistically enhanced speaking style, improves children's social language turn-taking and language skills. Research-based interventions targeting social aspects of parent-child interactions can enhance language outcomes. parentese speech | conversational turns | language intervention | parent coaching | social interaction I n the 1960s, anthropologists and linguists documenting speaking patterns across diverse languages noted an unusual speech "register" when adults addressed their young children (1). Originally termed "baby talk," this pattern of speaking had a simpler phonology and grammar, fewer and simpler lexical items, a higher pitch, unusual intonation contours (1), and was observed being used by mothers, fathers, and siblings across many cultures, in both spoken and signed languages (2-4). Later research on infant-directed speech, then termed "motherese" and eventually "parentese" because both genders used it, revealed a unique acoustic signature. Adults speaking parentese used a nearly octave increase in habitual pitch, spoke with exaggerated pitch contours, and used a significantly slower tempo with elongated vowels (5-7).Infants were shown in several studies to prefer parentese when given a choice between parentese and standard adult-directed speech (8-10). Infants' preference for parentese gathered sufficient scientific attention to merit two large studies examining the robustness of the effect across cultures and languages. The first (11), exami...

Previous studies reveal an association between particular features of parental language input and advances in children's language learning. However, it is not known whether parent coaching aimed to enhance specific input components would (a) successfully increase these components in parents' language input and (b) result in concurrent increases in children's language development. The present randomized controlled trial assigned families of typically developing 6‐month‐old infants to Intervention (parent coaching) and Control (no coaching) groups. Families were equivalent on socioeconomic status, infants' gender, and infants' age. Parent coaching took place when infants were 6 and 10 months of age, and included quantitative and qualitative linguistic feedback on the amount of child‐directed speech, back‐and‐forth interactions, and parentese speech style. These variables were derived from each family's first‐person LENA recordings at home. Input variables and infant language were measured at 6, 10, and 14 months. Parent coaching significantly enhanced language input as measured by two social interaction variables: percentage of speech directed to the child and percentage of parentese speech. These two variables were correlated, and were both related to growth in infant babbling between 6 and 14 months. Intervention infants showed greater growth in babbling than Control infants. Furthermore, at 14 months, Intervention infants produced significantly more words than Control infants, as indicated by LENA recordings and parent report via the MacArthur‐Bates Communicative Developmental Inventory. Together, these results indicate that parent coaching can enrich specific aspects of parental language input, and can immediately and positively impact child language outcomes. A video abstract of this article can be viewed at: https://youtu.be/7wqR28gPiwo

Language experience shapes infants' abilities to process speech sounds, with universal phonetic discrimination abilities narrowing in the second half of the first year. Brain measures reveal a corresponding change in neural discrimination as the infant brain becomes selectively sensitive to its native language(s). Whether and how bilingual experience alters the transition to native language specific phonetic discrimination is important both theoretically and from a practical standpoint. Using whole head magnetoencephalography (MEG), we examined brain responses to Spanish and English syllables in Spanish-English bilingual and English monolingual 11-month-old infants. Monolingual infants showed sensitivity to English, while bilingual infants were sensitive to both languages. Neural responses indicate that the dual sensitivity of the bilingual brain is achieved by a slower transition from acoustic to phonetic sound analysis, an adaptive and advantageous response to increased variability in language input. Bilingual neural responses extend into the prefrontal and orbitofrontal cortex, which may be related to their previously described bilingual advantage in executive function skills. A video abstract of this article can be viewed at: https://youtu.be/TAYhj-gekqw.

Congenitally deaf individuals receive little or no auditory input, and when raised by deaf parents, they acquire sign as their native and primary language. We asked two questions regarding how the deaf brain in humans adapts to sensory deprivation: (1) Is meaning extracted and integrated from signs using the same classical left hemisphere fronto-temporal network used for speech in hearing individuals, and (2) in deafness, is superior temporal cortex encompassing primary and secondary auditory regions reorganized to receive and process visual sensory information at short latencies? Using magnetoencephalography (MEG) constrained by individual cortical anatomy obtained with magnetic resonance imaging (MRI), we examined an early time window associated with sensory processing and a late time window associated with lexico-semantic integration. We found that sign in deaf individuals and speech in hearing individuals activate a highly similar left fronto-temporal network (including superior temporal regions surrounding auditory cortex) during lexico-semantic processing, but only speech in hearing individuals activates auditory regions during sensory processing. Thus, neural systems dedicated to processing high-level linguistic information are utilized for processing language regardless of modality or hearing status, and we do not find evidence for re-wiring of afferent connections from visual systems to auditory cortex.