The role of lexical and prosodic characteristics of mothers' child-directed speech for the early vocabulary development of Italian children with cochlear implants.

BACKGROUND: Variability in the vocabulary outcomes of children with cochlear implants (CIs) is partially explained by child-directed speech (CDS) characteristics. Yet, relatively little is known about whether and how mothers adapt their lexical and prosodic characteristics to the child's hearing status (before and after implantation, and compared with groups with normal hearing (NH)) and how important they are in affecting vocabulary development in the first 12 months of hearing experience. AIMS: To investigate whether mothers of children with CIs produce CDS with similar lexical and prosodic characteristics compared with mothers of age-matched children with NH, and whether they modify these characteristics after implantation. In addition, to investigate whether mothers' CDS characteristics predict children's early vocabulary skills before and after implantation. METHODS & PROCEDURES: A total of 34 dyads (17 with NH, 17 with children with CIs; ages = 9-32 months), all acquiring Italian, were involved in the study. Mothers' and children's lexical quantity (tokens) and variety (types), mothers' prosodic characteristics (pitch range and variability), and children's vocabulary skills were assessed at two time points, corresponding to before and 1 year post-CI activation for children with CIs. Children's vocabulary skills were assessed using parent reports; lexical and prosodic characteristics were observed in semi-structured mother-child interactions. OUTCOMES & RESULTS: Results showed that mothers of children with CIs produced speech with similar lexical quantity but lower lexical variety, and with increased pitch range and variability, than mothers of children with NH. Mothers generally increased their lexical quantity and variety and their pitch range between sessions. Children with CIs showed reduced expressive vocabulary and lower lexical quantity and variety than their peers 12 months post-CI activation. Mothers' prosodic characteristics did not explain variance in children's vocabulary skills; their lexical characteristics predicted children's early vocabulary and lexical outcomes, especially in the NH group, but were not related to later language development. CONCLUSIONS & IMPLICATIONS: Our findings confirm previous studies on other languages and support the idea that the lexical characteristics of mothers' CDS have a positive effect on children's early measures of vocabulary development across hearing groups, whereas prosodic cues play a minor role. Greater input quantity and quality may assist children in the building of basic language model representations, whereas pitch cues may mainly serve attentional and emotional processes. Results emphasize the need for additional longitudinal studies investigating the input received from other figures surrounding the child and its role for children's language development. WHAT THIS PAPER ADDS: What is already known on the subject Mothers' CDS is thought to facilitate and support language acquisition in children with various language developmental trajectories, including children with CIs. Because children with CIs are at risk for language delays and have acoustic processing limitations, their mothers may have to produce a lexically simpler but prosodically richer input, compared to mothers of children with NH. Yet, the literature reports mixed findings and no study to our knowledge has concurrently addressed the role of mothers' lexical and prosodic characteristics for children's vocabulary development before implantation and in the first 12 months of hearing experience. What this study adds to the existing knowledge The study shows that mothers of children with CIs produce input of similar quantity but reduced variety, and with heightened pitch characteristics, compared to mothers of children with NH. There was also a general increase in mothers' lexical quantity and variety, and in their pitch range, between sessions. Only their lexical characteristics predicted children's early vocabulary skills. Their lexical variety predicted children's expressive vocabulary and lexical variety only in the NH group. What are the practical and clinical implications of this work? These findings expand our knowledge about the effects of maternal input and may contribute to the improvement of early family-centred intervention programmes for supporting language development in children with CIs.

Lexical access and competition in bilingual children: The role of proficiency and the lexical similarity of the two languages.

Using a picture-auditory word recognition task, we examined how early child bilinguals access their languages and how the languages affect one another. Accuracy and response times in "false friends" (i.e., words with similar form but unrelated meanings) and semantically related words were compared with control conditions within and across languages and grades. Study 1 tested the performance of school-age children with balanced versus unbalanced knowledge of first-language (L1) Italian and second-language (L2) German. Study 2 compared unbalanced bilingual children with L1 Italian and L2 French or German to investigate the effect of lexical similarity in the children's languages. Children were found to activate both languages on receiving an auditory stimulus; performance in each language was affected by proficiency in the other language, degree of between-language similarity, and length of experience with each language. The BLINCS (Bilingual Language Interactive Network for Comprehension of Speech) model was invoked as a plausible framework for conceptualizing the nature of bilingual phonolexical representation and its effect on word recognition.

Narrative skills and language comprehension in preschool children with cochlear implants: A comparison with children with Developmental Language Disorder or typical development.

INTRODUCTION: The narrative skills of children with cochlear implants (CIs) are fragile, but the factors at play and whether these difficulties could be similar to those detected in language impairment are not clear. The present study aims to assess, at the microstructural level, narrative skills, comparing children with CIs with children with Developmental Language Disorder (DLD) or Typical Development (TD). Furthermore, the relationship between verbal (lexical and morphosyntactic) comprehension and narrative skills across groups is investigated. METHODS: The narratives of 19 children with CIs (Mage = 62.42 months, SD = 6.83), 13 children with DLD (Mage = 65.38 months, SD = 4.27), and 18 preschool children with TD (Mage = 63.67 months, SD = 4.31) were assessed in a standardized task. Articles, prepositions, pronouns, gender and number agreement, accuracy in the use of verbs, and number of arguments in each sentence were analysed. Lexical and morphosyntactic comprehension were also assessed. Performance was compared across groups using ANOVAs or Kruskal-Wallis tests. The role of lexical and morphosyntactic comprehension in predicting each morphological and syntactic element in the narrative task was examined using linear regressions. RESULTS: Data analysis showed that both children with CIs and DLD had fragilities in narration, both in the morphological and syntactic components. Although some differences between children with CIs and those with DLD emerged in descriptive analyses, these were not statistically significant. Regressions showed that morphosyntactic comprehension predicted the number of pronouns produced only in the TD group. CONCLUSIONS: The scarce differences between CI and DLD groups and the absence of an effect of morphosyntactic comprehension on pronoun production may be due to their low production of these elements in the narrative task and/or to a difficulty in managing pronouns in an expressive task regardless of their ability to comprehend them. Potential implications of these results are discussed.

Individual differences in neural markers of beat processing relate to spoken grammar skills in six-year-old children.

Based on the idea that neural entrainment establishes regular attentional fluctuations that facilitate hierarchical processing in both music and language, we hypothesized that individual differences in syntactic (grammatical) skills will be partly explained by patterns of neural responses to musical rhythm. To test this hypothesis, we recorded neural activity using electroencephalography (EEG) while children (N = 25) listened passively to rhythmic patterns that induced different beat percepts. Analysis of evoked beta and gamma activity revealed that individual differences in the magnitude of neural responses to rhythm explained variance in six-year-olds' expressive grammar abilities, beyond and complementarily to their performance in a behavioral rhythm perception task. These results reinforce the idea that mechanisms of neural beat entrainment may be a shared neural resource supporting hierarchical processing across music and language and suggest a relevant marker of the relationship between rhythm processing and grammar abilities in elementary-school-age children, previously observed only behaviorally.

Exploring individual differences in musical rhythm and grammar skills in school-aged children with typically developing language.

A growing number of studies have shown a connection between rhythmic processing and language skill. It has been proposed that domain-general rhythm abilities might help children to tap into the rhythm of speech (prosody), cueing them to prosodic markers of grammatical (syntactic) information during language acquisition, thus underlying the observed correlations between rhythm and language. Working memory processes common to task demands for musical rhythm discrimination and spoken language paradigms are another possible source of individual variance observed in musical rhythm and language abilities. To investigate the nature of the relationship between musical rhythm and expressive grammar skills, we adopted an individual differences approach in N = 132 elementary school-aged children ages 5-7, with typical language development, and investigated prosodic perception and working memory skills as possible mediators. Aligning with the literature, musical rhythm was correlated with expressive grammar performance (r = 0.41, p < 0.001). Moreover, musical rhythm predicted mastery of complex syntax items (r = 0.26, p = 0.003), suggesting a privileged role of hierarchical processing shared between musical rhythm processing and children's acquisition of complex syntactic structures. These relationships between rhythm and grammatical skills were not mediated by prosodic perception, working memory, or non-verbal IQ; instead, we uncovered a robust direct effect of musical rhythm perception on grammatical task performance. Future work should focus on possible biological endophenotypes and genetic influences underlying this relationship.

Ecological Impact of End-of-Life-Tire (ELT)-Derived Rubbers: Acute and Chronic Effects at Organism and Population Levels.

Considering the large amount of tires that reach the end of life every year, the aim of this study was the evaluation of both acute and chronic effects of end-of-life-tire (ELT)-derived rubber granules (ELT-dg) and powder (ELT-dp) on a freshwater trophic chain represented by the green alga Pseudokirchneriella subcapitata, the crustacean Daphnia magna and the teleost Danio rerio (zebrafish). Adverse effects were evaluated at the organism and population levels through the classical ecotoxicological tests. Acute tests on D. magna and D. rerio revealed a 50% effect concentration (EC50) > 100.0 mg/L for both ELT-dg and ELT-dp. Chronic exposures had a lowest observed effect concentration (LOEC) of 100.0 mg/L for both ELT-dg and ELT-dp on P. subcapitata grow rate and yield. LOEC decreased in the other model organisms, with a value of 9.8 mg/L for D. magna, referring to the number of living offspring, exposed to ELT-dg suspension. Similarly, in D. rerio, the main results highlighted a LOEC of 10.0 mg/L regarding the survival and juvenile weight parameters for ELT-dg and a LOEC of 10.0 mg/L concerning the survival and abnormal behavior in specimens exposed to ELT-dp. Tested materials exhibited a threshold of toxicity of 9.8 mg/L, probably a non-environmental concentration, although further investigations are needed to clarify the potential ecological impact of these emerging contaminants.

Do Acoustic Environment Characteristics Affect the Lexical Development of Children With Cochlear Implants? A Longitudinal Study Before and After Cochlear Implant Activation.

Purpose This study investigates the acoustic environment of children with cochlear implants (CIs) and the relationship between exposure to speech, in noise and in quiet, and the children's lexical production up to 1 year after CI activation, while controlling for the effect of early individual differences in receptive vocabulary growth. Method Eighteen children with CIs were observed at 3, 6, and 12 months after CI activation. Children's spontaneous word production during interaction with their mothers (types and tokens) and their expressive and receptive vocabulary size were considered. The characteristics of the acoustic environments in terms of acoustic scenes (speech in noise or in quiet, quiet, noise, music, and other) and of loudness ranges were assessed using data logging of the children's devices. Results Data analysis showed that both the number of tokens and the number of types produced 1 year after CI activation were affected by the children's exposure to speech in quiet with a loudness range between 40 and 69 dB. Expressive vocabulary size and types were affected by the receptive vocabulary knowledge that the children achieved over the first 3 months after CI activation. Conclusions Our data support the role of speech environment and individual differences in early comprehension on lexical production. The importance of exposure to speech with particular characteristics for the lexical development of children with CIs and the implications for clinical practice are discussed.

Is atypical rhythm a risk factor for developmental speech and language disorders?

Although a growing literature points to substantial variation in speech/language abilities related to individual differences in musical abilities, mainstream models of communication sciences and disorders have not yet incorporated these individual differences into childhood speech/language development. This article reviews three sources of evidence in a comprehensive body of research aligning with three main themes: (a) associations between musical rhythm and speech/language processing, (b) musical rhythm in children with developmental speech/language disorders and common comorbid attentional and motor disorders, and (c) individual differences in mechanisms underlying rhythm processing in infants and their relationship with later speech/language development. In light of converging evidence on associations between musical rhythm and speech/language processing, we propose the Atypical Rhythm Risk Hypothesis, which posits that individuals with atypical rhythm are at higher risk for developmental speech/language disorders. The hypothesis is framed within the larger epidemiological literature in which recent methodological advances allow for large-scale testing of shared underlying biology across clinically distinct disorders. A series of predictions for future work testing the Atypical Rhythm Risk Hypothesis are outlined. We suggest that if a significant body of evidence is found to support this hypothesis, we can envision new risk factor models that incorporate atypical rhythm to predict the risk of developing speech/language disorders. Given the high prevalence of speech/language disorders in the population and the negative long-term social and economic consequences of gaps in identifying children at-risk, these new lines of research could potentially positively impact access to early identification and treatment. This article is categorized under: Linguistics > Language in Mind and Brain Neuroscience > Development Linguistics > Language Acquisition.

Preverbal Production and Early Lexical Development in Children With Cochlear Implants: A Longitudinal Study Following Pre-implanted Children Until 12 Months After Cochlear Implant Activation.

Studies have shown that children vary in the trajectories of their language development after cochlear implant (CI) activation. The aim of the present study is to assess the preverbal and lexical development of a group of 20 Italian-speaking children observed longitudinally before CI activation and at three, 6 and 12 months after CI surgery (mean age at the first session: 17.5 months; SD: 8.3; and range: 10-35). The group of children with CIs (G-CI) was compared with two groups of normally-hearing (NH) children, one age-matched (G-NHA; mean age at the first session: 17.4 months; SD: 8.0; and range: 10-34) and one language-matched (G-NHL; n = 20; mean age at the first session: 11.2 months; SD: 0.4; and range: 11-12). The spontaneous interactions between children and their mothers during free-play were transcribed. Preverbal babbling production and first words were considered for each child. Data analysis showed significant differences in babbling and word production between groups, with a lower production of words in children with CIs compared to the G-NHA group and a higher production of babbling compared to the G-NHL children. Word production 1 year after activation was significantly lower for the children with CIs than for language-matched children only when maternal education was controlled for. Furthermore, latent class growth analysis showed that children with CIs belonged mainly to classes that exhibited a low level of initial production but also progressive increases over time. Babbling production had a statistically significant effect on lexical growth but not on class membership, and only for groups showing slower and constant increases. Results highlight the importance of preverbal vocal patterns for later lexical development and may support families and speech therapists in the early identification of risk and protective factors for language delay in children with CIs.