Vocal development in a large-scale crosslinguistic corpus

Follow-up of expressive language and general development at 12, 18 and 36 months for children with no canonical babbling at 10 months

Little is known about the developmental trajectories in children who do not use canonical babbling (CB) at 10 months. The aim was to examine how speech, language, cognitive and motor abilities developed in children without CB. For 15 children identified as not having CB, consonant production, expressive vocabulary and general development were assessed at 12, 18 and 36 months from audio-video recordings. Twelve (79%) children still lacked CB at 12 months. At 18 months, six (40%) had parent-reported expressive vocabulary results below the 10th percentile, and two (14%) did not use dental/alveolar stops. The percentage of consonants correct for the group was at the level of peers at 36 months (89%, SD 0.17), but the group had fewer established target consonants than age norms. Most children had a small expressive vocabulary in comparison with Swedish age norms for younger children as well as with age-matched norms for other Nordic languages. The general development (Bayley-III) for three children (21%) who did not use speech was 1-2 SD below the average range in at least one domain (cognitive, language or motor), but the results for the whole group were within the average range. In conclusion, the heterogeneity in early consonant development in the study group resembles that of children in clinical groups with known risk for speech and language difficulties and the expressive vocabulary resembles that of children with delayed expressive vocabulary. For about one-fifth of the children, the absence of canonical babbling at age 10 months could be seen as an early sign of a more comprehensive developmental disability.

Vocal Characteristics of Children With Cerebral Palsy and Anarthria

PURPOSE

This study aimed to investigate the vocal characteristics of children with cerebral palsy (CP) and anarthria using the stage model of vocal development.

METHOD

Vocal characteristics of 39 children with CP and anarthria around 4 years of age were analyzed from laboratory-based caregiver-child interactions. Perceptual coding analysis was conducted using the Stark Assessment of Early Vocal Development-Revised to examine vocal complexity, volubility, and consonant diversity.

RESULTS

Children predominately produced vocalizations corresponding to the two earliest stages of vocal development characterized by vowel-like utterances. They showed a limited attainment of consonantal features with low consonant diversity and variably low vocal rates.

CONCLUSIONS

Our results demonstrate that underlying neurological impairments resulting in an anarthric status in children with CP affect the progression of speech motor development and their ability to advance beyond early vocal stages. These findings highlight the importance of considering alternative communication modalities for children demonstrating similar vocal characteristics beyond expected periods of development.

Child-directed speech in a large sample of U.S. mothers with low income

Research on early language input and socioeconomic status typically relies on correlations in small convenience samples. Using data from Baby's First Years, this paper assesses the causal impact of monthly, unconditional cash transfers on child-directed speech and child vocalizations among a large, racially diverse sample of low-income U.S. mothers and their 1-year-olds (N = 563; 48% girls; 2019-2020). The monthly, unconditional cash transfers did not impact mothers' child-directed speech during a 10-min at-home play session (effect sizes range from -.08 to .02), though there was wide variability within this sample. Future work will assess the impact of the continued cash transfer on children's language input and development over time.

Infants who are rarely spoken to nevertheless understand many words

Theories of language development-informed largely by studies of Western, middleclass infants-have highlighted the language that caregivers direct to children as a key driver of language learning. However, some have argued that language development unfolds similarly across environmental contexts, including those in which childdirected language is scarce. This raises the possibility that children are able to learn from other sources of language in their environments, particularly the language directed to others in their environment. We explore this hypothesis with infants in an indigenous Tseltal-speaking community in Southern Mexico who are rarely spoken to, yet have the opportunity to overhear a great deal of other-directed language by virtue of being carried on their mothers' backs. Adapting a previously established gaze-tracking method for detecting early word knowledge to our field setting, we find that Tseltal infants exhibit implicit knowledge of common nouns (Exp. 1), analogous to their US peers who are frequently spoken to. Moreover, they exhibit comprehension of Tseltal honorific terms that are exclusively used to greet adults in the community (Exp. 2), representing language that could only have been learned through overhearing. In so doing, Tseltal infants demonstrate an ability to discriminate words with similar meanings and perceptually similar referents at an earlier age than has been shown among Western children. Together, these results suggest that for some infants, learning from overhearing may be an important path toward developing language.

Globally, songs and instrumental melodies are slower and higher and use more stable pitches than speech: A Registered Report

Both music and language are found in all known human societies, yet no studies have compared similarities and differences between song, speech, and instrumental music on a global scale. In this Registered Report, we analyzed two global datasets: (i) 300 annotated audio recordings representing matched sets of traditional songs, recited lyrics, conversational speech, and instrumental melodies from our 75 coauthors speaking 55 languages; and (ii) 418 previously published adult-directed song and speech recordings from 209 individuals speaking 16 languages. Of our six preregistered predictions, five were strongly supported: Relative to speech, songs use (i) higher pitch, (ii) slower temporal rate, and (iii) more stable pitches, while both songs and speech used similar (iv) pitch interval size and (v) timbral brightness. Exploratory analyses suggest that features vary along a "musi-linguistic" continuum when including instrumental melodies and recited lyrics. Our study provides strong empirical evidence of cross-cultural regularities in music and speech.

Predicting Social Competence in Autistic and Non-Autistic Children: Effects of Prosody and the Amount of Speech Input

PURPOSE

Autistic individuals often face challenges perceiving and expressing emotions, potentially stemming from differences in speech prosody. Here we explore how autism diagnoses between groups, and measures of social competence within groups may be related to, first, children's speech characteristics (both prosodic features and amount of spontaneous speech), and second, to these two factors in mothers' speech to their children.

METHODS

Autistic (n = 21) and non-autistic (n = 18) children, aged 7-12 years, participated in a Lego-building task with their mothers, while conversational speech was recorded. Mean F0, pitch range, pitch variability, and amount of spontaneous speech were calculated for each child and their mother.

RESULTS

The results indicated no differences in speech characteristics across autistic and non-autistic children, or across their mothers, suggesting that conversational context may have large effects on whether differences between autistic and non-autistic populations are found. However, variability in social competence within the group of non-autistic children (but not within autistic children) was predictive of children's mean F0, pitch range and pitch variability. The amount of spontaneous speech produced by mothers (but not their prosody) predicted their autistic children's social competence, which may suggest a heightened impact of scaffolding for mothers of autistic children.

CONCLUSION

Together, results suggest complex interactions between context, social competence, and adaptive parenting strategies in driving prosodic differences in children's speech.

Within arms reach: Physical proximity shapes mother-infant language exchanges in real-time

During everyday interactions, mothers and infants achieve behavioral synchrony at multiple levels. The ebb-and-flow of mother-infant physical proximity may be a central type of synchrony that establishes a common ground for infant-mother interaction. However, the role of proximity in language exchanges is relatively unstudied, perhaps because structured tasks-the common setup for observing infant-caregiver interactions-establish proximity by design. We videorecorded 100 mothers (U.S. Hispanic N = 50, U.S. Non-Hispanic N = 50) and their 13- to 23-month-old infants during natural activity at home (1-to-2 h per dyad), transcribed mother and infant speech, and coded proximity continuously (i.e., infants and mother within arms reach). In both samples, dyads entered proximity in a bursty temporal pattern, with bouts of proximity interspersed with bouts of physical distance. As hypothesized, Non-Hispanic and Hispanic mothers produced more words and a greater variety of words when within arms reach than out of arms reach. Similarly, infants produced more utterances that contained words when close to mother than when not. However, infants babbled equally often regardless of proximity, generating abundant opportunities to play with sounds. Physical proximity expands opportunities for language exchanges and infants' communicative word use, although babies accumulate massive practice babbling even when caregivers are not proximal.

Infant-directed speech does not always involve exaggerated vowel distinctions: Evidence from Danish

This study compared the acoustic properties of 26 (100% female, 100% monolingual) Danish caregivers' spontaneous speech addressed to their 11- to 24-month-old infants (infant-directed speech, IDS) and an adult experimenter (adult-directed speech, ADS). The data were collected between 2016 and 2018 in Aarhus, Denmark. Prosodic properties of Danish IDS conformed to cross-linguistic patterns, with a higher pitch, greater pitch variability, and slower articulation rate than ADS. However, an acoustic analysis of vocalic properties revealed that Danish IDS had a reduced or similar vowel space, higher within-vowel variability, raised formants, and lower degree of vowel discriminability compared to ADS. None of the measures, except articulation rate, showed age-related differences. These results push for future research to conduct theory-driven comparisons across languages with distinct phonological systems.

Combining observational and experimental approaches to the development of language and communication in rural samples: Opportunities and challenges

Multiple approaches - including observational and experimental - are necessary to articulate powerful theories of learning. Our field's key questions, which rely on these varied methods, are still open. How do children perceive and produce language? What do they encounter in their linguistic input? What does the learner bring to the task of acquisition? Considerable progress has been made for the development of spoken English (especially by North American learners). Yet there is still a great deal to discover about how children in other populations proceed, especially populations in rural settings. To examine language learning in these populations, we need a multi-method approach. However, adapting and integrating methods, particularly experimental ones, to new settings can present immense challenges. In this paper, we discuss the opportunities and challenges facing researchers who aim to use a multimethodological approach in rural samples, and what the field of language acquisition can do to promote such work.

Talking to talkers: Infants' talk status, but not their gender, is related to language input

Prior research points to gender differences in some early language skills, but is inconclusive about the mechanisms at play, providing evidence that both infants' early input and productions may differ by gender. This study examined the linguistic input and early productions of 44 American English-learning infants (93% White) in a longitudinal sample of home recordings collected at 6-17 months (in 2014-2016). Girls produced more unique words than boys (Cohen's d = .67) and this effect grew with age, but there were no significant gender differences in language input (d = .22-.24). Instead, caregivers talked more to infants who had begun to talk (d = .93-.97), regardless of gender. Therefore, prior results highlighting gender-based input differences may have been due, at least partly, to this talking-to-talkers effect.

Emerging Verbal Functions in Early Infancy: Lessons from Observational and Computational Approaches on Typical Development and Neurodevelopmental Disorders

OBJECTIVES

Research on typically developing (TD) children and those with neurodevelopmental disorders and genetic syndromes was targeted. Specifically, studies on autism spectrum disorder, Down syndrome, Rett syndrome, fragile X syndrome, cerebral palsy, Angelman syndrome, tuberous sclerosis complex, Williams-Beuren syndrome, Cri-du-chat syndrome, Prader-Willi syndrome, and West syndrome were searched. The objectives are to review observational and computational studies on the emergence of (pre-)babbling vocalisations and outline findings on acoustic characteristics of early verbal functions.

METHODS

A comprehensive review of the literature was performed including observational and computational studies focusing on spontaneous infant vocalisations at the pre-babbling age of TD children, individuals with genetic or neurodevelopmental disorders.

RESULTS

While there is substantial knowledge about early vocal development in TD infants, the pre-babbling phase in infants with neurodevelopmental and genetic syndromes is scarcely scrutinised. Related approaches, paradigms, and definitions vary substantially and insights into the onset and characteristics of early verbal functions in most above-mentioned disorders are missing. Most studies focused on acoustic low-level descriptors (e.g. fundamental frequency) which bore limited clinical relevance. This calls for computational approaches to analyse features of infant typical and atypical verbal development.

CONCLUSIONS

Pre-babbling vocalisations as precursor for future speech-language functions may reveal valuable signs for identifying infants at risk for atypical development. Observational studies should be complemented by computational approaches to enable in-depth understanding of the developing speech-language functions. By disentangling features of typical and atypical early verbal development, computational approaches may support clinical screening and evaluation.

LANGUAGE EXPOSURE PREDICTS CHILDREN'S PHONETIC PATTERNING: EVIDENCE FROM LANGUAGE SHIFT

Although understanding the role of the environment is central to language acquisition theory, rarely has this been studied for children's phonetic development, and receptive and expressive language experiences in the environment are not distinguished. This last distinction may be crucial for child speech production in particular, because production requires coordination of low-level speech-motor planning with high-level linguistic knowledge. In this study, the role of the environment is evaluated in a novel way-by studying phonetic development in a bilingual community undergoing rapid language shift. This sociolinguistic context provides a naturalistic gradient of the amount of children's exposure to two languages and the ratio of expressive to receptive experiences. A large-scale child language corpus encompassing over 500 hours of naturalistic South Bolivian Quechua and Spanish speech was efficiently annotated for children's and their caregivers' bilingual language use. These estimates were correlated with children's patterns in a series of speech production tasks. The role of the environment varied by outcome: children's expressive language experience best predicted their performance on a coarticulation-morphology measure, while their receptive experience predicted performance on a lower-level measure of vowel variability. Overall these bilingual exposure effects suggest a pathway for children's role in language change whereby language shift can result in different learning outcomes within a single speech community. Appropriate ways to model language exposure in development are discussed.

Infants later diagnosed with autism have lower canonical babbling ratios in the first year of life

BACKGROUND

Canonical babbling-producing syllables with a mature consonant, full vowel, and smooth transition-is an important developmental milestone that typically occurs in the first year of life. Some studies indicate delayed or reduced canonical babbling in infants at high familial likelihood for autism spectrum disorder (ASD) or who later receive an ASD diagnosis, but evidence is mixed. More refined characterization of babbling in the first year of life in infants with high likelihood for ASD is needed.

METHODS

Vocalizations produced at 6 and 12 months by infants (n = 267) taking part in a longitudinal study were coded for canonical and non-canonical syllables. Infants were categorized as low familial likelihood (LL), high familial likelihood diagnosed with ASD at 24 months (HL-ASD) or not diagnosed (HL-Neg). Language delay was assessed based on 24-month expressive and receptive language scores. Canonical babble ratio (CBR) was calculated by dividing the number of canonical syllables by the number of total syllables. Generalized linear (mixed) models were used to assess the relationship between group membership and CBR, controlling for site, sex, and maternal education. Logistic regression was used to assess whether canonical babbling ratios at 6 and 12 months predict 24-month diagnostic outcome.

RESULTS

No diagnostic group differences in CBR were detected at 6 months, but HL-ASD infants produced significantly lower CBR than both the HL-Neg and LL groups at 12 months. HL-Neg infants with language delay also showed reduced CBR at 12 months. Neither 6- nor 12-month CBR was significant predictors of 24-month diagnostic outcome (ASD versus no ASD) in logistic regression.

LIMITATIONS

Small numbers of vocalizations produced by infants at 6 months may limit the reliability of CBR estimates. It is not known if results generalize to infants who are not at high familial likelihood, or infants from more diverse racial and socioeconomic backgrounds.

CONCLUSIONS

Lower canonical babbling ratios are apparent by the end of the first year of life in ASD regardless of later language delay, but are also observed for infants with later language delay without ASD. Canonical babbling may lack specificity as an early marker when used on its own.

Using big data from long-form recordings to study development and optimize societal impact

Big data are everywhere. In this chapter, we focus on one source: long-form, child-centered recordings collected using wearable technologies. Because these recordings are simultaneously unobtrusive and encompassing, they may be a breakthrough technology for clinicians and researchers from several diverse fields. We demonstrate this possibility by outlining three applications for the recordings-clinical treatment, large-scale interventions, and language documentation-where we see the greatest potential. We argue that incorporating these recordings into basic and applied research will result in more equitable treatment of patients, more reliable measurements of the effects of interventions on real-world behavior, and deeper scientific insights with less observational bias. We conclude by outlining a proposal for a semistructured online platform where vast numbers of long-form recordings could be hosted and more representative, less biased algorithms could be trained.

Language input to infants of different socioeconomic statuses: A quantitative meta-analysis

For the past 25 years, researchers have investigated language input to children from high- and low-socioeconomic status (SES) families. Hart and Risley first reported a "30 Million Word Gap" between high-SES and low-SES children. More recent studies have challenged the size or even existence of this gap. The present study is a quantitative meta-analysis on socioeconomic differences in language input to young children, which aims to systematically integrate decades of research on this topic. We analyzed 19 studies and found a significant effect of SES on language input quantity. However, this effect was moderated by the type of language included in language quantity measures: studies that include only child-directed speech in their language measures find a large SES difference, while studies that include all speech in a child's environment find no effect of SES. These results support recent work suggesting that methodological decisions can affect researchers' estimates of the "word gap." Overall, we find that young children from low-SES homes heard less child-directed speech than children from mid- to high-SES homes, though this difference was much smaller than Hart & Risley's "30 Million Word Gap." Finally, we underscore the need for more cross-cultural work on language development and the forces that may contribute to it, highlighting the opportunity for better integration of observational, experimental, and intervention-based approaches.

Quantifying Everyday Ecologies: Principles for Manual Annotation of Many Hours of Infants' Lives

Everyday experiences are the experiences available to shape developmental change. Remarkable advances in devices used to record infants' and toddlers' everyday experiences, as well as in repositories to aggregate and share such recordings across teams of theorists, have yielded a potential gold mine of insights to spur next-generation theories of experience-dependent change. Making full use of these advances, however, currently requires manual annotation. Manually annotating many hours of everyday life is a dedicated pursuit requiring significant time and resources, and in many domains is an endeavor currently lacking foundational facts to guide potentially consequential implementation decisions. These realities make manual annotation a frequent barrier to discoveries, as theorists instead opt for narrower scoped activities. Here, we provide theorists with a framework for manually annotating many hours of everyday life designed to reduce both theoretical and practical overwhelm. We share insights based on our team's recent adventures in the previously uncharted territory of everyday music. We identify principles, and share implementation examples and tools, to help theorists achieve scalable solutions to challenges that are especially fierce when annotating extended timescales. These principles for quantifying everyday ecologies will help theorists collectively maximize return on investment in databases of everyday recordings and will enable a broad community of scholars—across institutions, skillsets, experiences, and working environments—to make discoveries about the experiences upon which development may depend.

Describing Vocalizations in Young Children: A Big Data Approach Through Citizen Science Annotation

Purpose Recording young children's vocalizations through wearables is a promising method to assess language development. However, accurately and rapidly annotating these files remains challenging. Online crowdsourcing with the collaboration of citizen scientists could be a feasible solution. In this article, we assess the extent to which citizen scientists' annotations align with those gathered in the lab for recordings collected from young children. Method Segments identified by Language ENvironment Analysis as produced by the key child were extracted from one daylong recording for each of 20 participants: 10 low-risk control children and 10 children diagnosed with Angelman syndrome, a neurogenetic syndrome characterized by severe language impairments. Speech samples were annotated by trained annotators in the laboratory as well as by citizen scientists on Zooniverse. All annotators assigned one of five labels to each sample: Canonical, Noncanonical, Crying, Laughing, and Junk. This allowed the derivation of two child-level vocalization metrics: the Linguistic Proportion and the Canonical Proportion. Results At the segment level, Zooniverse classifications had moderate precision and recall. More importantly, the Linguistic Proportion and the Canonical Proportion derived from Zooniverse annotations were highly correlated with those derived from laboratory annotations. Conclusions Annotations obtained through a citizen science platform can help us overcome challenges posed by the process of annotating daylong speech recordings. Particularly when used in composites or derived metrics, such annotations can be used to investigate early markers of language delays.