Infant-directed Speech Research Articles

Prosodic variation between contexts in infant-directed speech.

Speakers consider their listeners and adjust the way they communicate. One well-studied example is the register of infant-directed speech (IDS), which differs acoustically from speech directed to adults. However, little work has explored how parents adjust speech to infants across different contexts. This is important because infants and parents engage in many activities throughout each day. The current study tests whether the properties of IDS in English vary across three in-lab tasks (sorting objects, free play, and storytelling). We analysed acoustic features associated with prosody, including mean fundamental frequency (F0, perceived as pitch), F0 range, and word rate. We found that both parents' pitch ranges and word rates varied depending on the task in IDS. The storytelling task stood out among the tasks for having a wider pitch range and faster word rate. The results depict how context can drive parents' speech adjustments to infants.

How strong is the relationship between caregiver speech and language development? A meta-analysis.

A growing body of research has found that talking to young children is positively associated with language outcomes. However, there is tremendous heterogeneity in the design of these studies, which could potentially affect the strength and reliability of this association. The present meta-analysis, comprising 4760 participants across 71 studies, goes beyond prior research by including: 1) more recent studies, 2) non-English-speaking populations, 3) more fine-grained categorization of measures of input, 4) additional moderators, and 5) a multilevel model design allowing us to consider multiple effect sizes per study. We find a moderate association between input and outcomes (R2=0.04-0.07) across four input measures, with some evidence of publication bias. We find no differences in effect size across any of the input measures. Child age and study duration moderated some effects of input. Our findings suggest that language input-outcome associations remain robust but modest across a multitude of contexts and measures.

More than just a happy talk? Evidence for functional pitch and utterance length modifications in infant-, spouse-, and dog-directed communication.

By comparing infant-directed speech to spouse- and dog-directed talk, we aimed to investigate how pitch and utterance length are modulated by speakers considering the speech context and the partner's expected needs and capabilities. We found that mean pitch was modulated in line with the partner's attentional needs, while pitch range and utterance length were modulated according to the partner's expected linguistic competence. In a situation with a nursery rhyme, speakers used the highest pitch and widest pitch range with all partners suggesting that infant-directed context greatly influences these acoustic features. Recent findings showed that these speakers expressed more intense positive emotions towards their infants and spouses than towards their dogs. Our results revealed different patterns, leading us to conclude that these acoustic features are not simple by-products of emotional speech. Instead, they are dynamically and functionally used in accordance with the speech context and the audience's expected needs and capabilities.

Motherese Directed at Prelinguistic Infants at Risk for Neurological Disorders: An Exploratory Study.

To investigate how a high risk for infant neurological impairment affects the quality of infant verbal interactions, and in particular properties of infant-directed speech, spontaneous interactions between 14 mothers and their 4.5-month-old infants at high risk for neurological disorders (7 female) were recorded and acoustically compared with those of 14 dyads with typically developing infants (8 female). Mothers of at-risk infants had proportionally less voicing, and the proportion of voicing decreased with increasing severity of the infants' long-term outcome. Follow-up analysis based on manual annotation of phonation style revealed breathy phonation as more common toward infants with more severe long-term outcomes (N=7; 44.7% of speech) than controls (N=14; 22.0%; p=0.005) or at-risk infants with typical or mildly abnormal long-term outcomes (N=7; 16.5%; p=0.002). The results indicate that maternal phonation style during early dyadic interactions is affected by the infant's neurological condition.

Acoustic Exaggeration Enhances Speech Discrimination in Young Autistic Children.

Child-directed speech (CDS), which amplifies acoustic and social features of speech during interactions with young children, promotes typical phonetic and language development. In autism, both behavioral and brain data indicate reduced sensitivity to human speech, which predicts absent, decreased, or atypical benefits of exaggerated speech signals such as CDS. This study investigates the impact of exaggerated fundamental frequency (F0) and voice-onset time on the neural processing of speech sounds in 22 Chinese-speaking autistic children aged 2-7 years old with a history of speech delays, compared with 25 typically developing (TD) peers. Electroencephalography (EEG) data were collected during passive listening to exaggerated and non-exaggerated syllables. A time-resolved multivariate pattern analysis (MVPA) was used to evaluate the potential effects of acoustic exaggeration on syllable discrimination in terms of neural decoding accuracy. For non-exaggerated syllables, neither the autism nor the TD group achieved above-chance decoding accuracy. In contrast, for exaggerated syllables, both groups achieved above-chance decoding, indicating significant syllable discrimination, with no difference in accuracy between the autism and TD groups. However, the temporal generalization patterns in the MVPA results revealed distinct neural mechanisms supporting syllable discrimination between the groups. Although the TD group demonstrated a left-hemisphere advantage for decoding and generalization, the autism group displayed similar decoding patterns between hemispheres. These findings highlight the potential of selective acoustic exaggeration to support speech learning in autistic children, underscoring the importance of tailored, sensory-based interventions.

Language processing in breastfed infants at risk of thiamine deficiency benefits from maternal thiamine supplementation.

In a double-blind, randomized controlled trial, we investigated relationships between infants' exposure to thiamine and their language-processing ability. Three hundred thirty-five lactating Cambodian mothers of 161 female/174 male infants received either 0, 1.2, 2.4, or 10 mg of thiamine daily, from 2 to 24 weeks postpartum. We assessed infants' language processing at 24 weeks via the infant-directed speech (IDS) task, measuring attentional enhancement to IDS versus adult-directed speech. Maternal thiamine supplementation displayed a small but statistically significant dose-response relationship to the magnitude of infants' IDS-elicited attentional enhancement (adjusted R² = 0.022, p = .011). As well, only infants whose mothers received a daily thiamine supplement of 10 mg showed fully robust IDS-related attentional enhancement. These findings showcase the IDS Task for monitoring the integrity of infants' language processing and underscore the importance of adequate thiamine early in life for ensuring optimal language development. (PsycInfo Database Record (c) 2024 APA, all rights reserved).

The richness of the stimulus: Constructional variation and development in child-directed speech

In a seminal study, Cameron-Faulkner et al. made two important observations about utterance-level constructions in English child-directed speech (CDS). First, they observed that canonical in/transitive sentences are surprisingly infrequent in child-direct speech (given that SVO word order is often thought to play a key role in the acquisition of English syntax). Second, they found that many CDS constructions are introduced by a lexical frame (such as Let’s. . ., There is . . ., or What do you . . .?). Using a much larger and more diverse dataset than Cameron-Faulkner et al., this study shows that CDS constructions vary with two important factors: (1) the interactive situation and (2) children’s age. While canonical in/transitive sentences are not particularly frequent in free toy play sessions, they are predominant in other social situations (e.g. during mealtimes and shared book reading sessions) and they increase in frequency as children get older. Furthermore, our data show that the different CDS constructions occur with different types of frames that vary in length and structure. Many CDS constructions include a short lexical frame consisting of one or two words, but questions are often introduced by extensive frames formed from a small set of lexical items that follow a power-law distribution. Considering these findings, we argue that the lexical and structural properties of CDS constructions are likely to facilitate the acquisition of English grammar and, in particular, the acquisition of questions.

Frequency, redundancy, and context in bilingual acquisition.

We report findings from a corpus-based investigation of three young children growing up in German-English bilingual environments (M = 3;0, Range = 2;3-3;11). Based on 2,146,179 single words and two-word combinations in naturalistic child speech (CS) and child-directed speech (CDS), we assessed the degree to which the frequency distribution of CDS predicted CS usage over time, and systematically identified CS that was over- or underrepresented in the corpus with respect to matched CDS baselines. Results showed that CDS explained 61% of the variance in CS single-word use and 19.3% of the variance in two-word combinations. Furthermore, the bilingual nature of the over or -underrepresented CS was partially attributable to factors beyond the corpus statistics, namely individual differences between children in their bilingual learning environment. In two out of the three children, overrepresented two-word combinations contained higher levels of syntactic slot redundancy than underrepresented CS. These results are discussed with respect to the role that redundancy plays in producing semiformulaic slot-and-frame patterns in CS.

How Do Enriched Speech Acoustics Support Language Acquisition in Children With Hearing Loss? A Narrative Review.

Language outcomes of children with hearing loss remain heterogeneous despite recent advances in treatment and intervention. Consonants with high frequency, in particular, continue to pose challenges to affected children's speech perception and production. In this review, the authors evaluate findings of how enriched child-directed speech and song might function as a form of early family-centered intervention to remedy the effects of hearing loss on consonant acquisition already during infancy. First, they review the developmental trajectory of consonant acquisition and how it is impeded by permanent pediatric hearing loss. Second, they assess how phonetic-prosodic and lexico-structural features of caregiver speech and song could facilitate acquisition of consonants in the high-frequency range. Last, recommendations for clinical routines and further research are expressed.

The "what" and "when" of language input to children: Linguistic and temporal predictors of vocabulary in 3-year-olds.

The quantity, quality, and complexity of language input are important for children's language development. This study examined how the detailed timing of this input relates to children's vocabulary at 3 years of age in 64 mother-child dyads (male = 28; female = 36; White = 69%, Black = 31%). Acoustical analysis of turn taking in mother-child dialogue found that more consistently timed maternal responses (lower response latency variability) were associated (r = .42, p < .001) with higher vocabulary (Peabody Picture Vocabulary Test, third edition) scores. In mothers with consistently timed responses, the complexity (mean length of utterance) of their child-directed speech significantly predicted (r = .53, p = .002) their children's vocabulary. This suggests that predictably timed contingent maternal responses provide an important learning cue that supports language development beyond the content of language input itself. (PsycInfo Database Record (c) 2024 APA, all rights reserved).

Infants' Preference for ID Speech in Face and Voice Extends to a Non‐Native Language

ABSTRACTInfants prefer infant‐directed (ID) speech. Concerning talking faces, previous research showed that 3‐ and 5‐month‐olds prefer faces that produce native ID than native adult‐directed (AD) speech, regardless of background speech being ID, AD or silent. Here, we explored whether infants also show a preference for non‐native ID speech. We presented 3‐ and 6‐month‐old infants with pairs of talking faces, one producing non‐native ID speech and the other non‐native AD speech, either in silence (Experiment 1) or accompanied by non‐native ID or AD background speech (Experiment 2). Results from Experiment 1 showed an overall preference for the silent ID talking faces across both age groups, suggesting a reliance on cross‐linguistic, potentially universal cues for this preference. However, Experiment 2 showed that preference for ID faces was disrupted at 3 months when auditory speech was present (ID or AD). At 6 months, infants maintained a preference for ID talking faces, but only when accompanied by ID speech. These findings show that auditory non‐native speech interferes with infants' processing of ID talking faces. They also suggest that by 6 months, infants start associating ID features from faces and voices irrespective of language familiarity, suggesting that infants' ID preference may be universal and amodal.

Child activity contexts and language environments

Abstract Activity contexts are increasingly recognized as important for the variation observed in the type and quantity of speech heard by children. However, there is little data from children’s everyday experiences to properly study this role. We analyzed the quantity of target child-directed speech (TDS) and other-directed speech (ODS) according to children’s activity contexts. We used Daylong Audio Recordings of American English children aged 6–17 months old from the Bergelson Seedlings corpus. A higher quantity of ODS per minute was observed in Solitary playful and exploratory activity contexts, while a higher quantity of TDS per minute was observed in Social activity contexts in comparison to other activity contexts. However, the interindividual variation found needs to be further explored. These results highlight the link between the language environment and activity contexts, and their importance for understanding child language development.

Approach to Complementary Feeding and Infant Language Use: An Observational Study.

Emerging research suggests that a more infant-led approach to complementary feeding may confer benefits for child language, but these findings are based on parent report studies. Using an observational approach this study examines whether different complementary feeding experiences relate to infant language exposure and language use. Fifty-eight parents recorded a typical infant mealtime in the home (mean infant age = 14 months, SD = 4.15). Observations were coded to measure the prevalence of infant-led and parent-led feeding using the Family Mealtime Coding Scheme. Caregiver language use (word types and token directed at the child, mean length of utterances in child-directed speech, responsiveness and initiations) and the number of infant vocalisations were coded in ELAN using CHAT conventions and parents completed the MacArthur Communicative Development Inventory short form as a measure of child language. Greater observed infant self-feeding was significantly associated with greater observed exposure to language from caregivers (r = 0.312 percentage of infant self-feeding correlated with caregiver word types directed at the child) and a greater number of infant vocalisations (r = 0.320 percentage of infant self-feeding correlated with number of child vocalisations produced). Structural Equation Modelling showed the relationship between infant self-feeding and infant vocalisations to be significantly mediated by enhanced quality and quantity of caregiver child-directed speech (model fit: χ2 [5] = 5.01, p = 0.415, CFI = 1.00 [NF = 0.98], RMSEA = 0.006). Differences in the approach to complementary feeding may shape infant's experiences in ways that support language exposure and use. Autonomy associated with infant self-feeding may enhance opportunities for social interaction.

Adaptive language strategies of an older sibling in bilingual German-Russian acquisition: A case study

Abstract In the beginning stages of language acquisition, children primarily learn language from their parents or main caregivers. Studies have shown that adults use a specific way of speaking when talking to young children, called child-directed speech (CDS). This type of speech has distinct characteristics across different aspects of language. Additionally, older siblings also communicate with their younger brothers and sisters. Studies suggest that even three- and four-year-olds change how they talk when interacting with younger children, like their siblings. Studies have shown that children’s speech patterns resemble those of adults, whether they grow up in monolingual or bilingual environments. However, research on bilingual language acquisition often focuses on how siblings influence the language development of younger children. In this study, we explore how children adapt their language in bilingual settings and focus on the older sibling. Specifically, we compare the speech of an older sibling, who speaks both German and Russian, when talking to their younger sibling and when talking to their parents. The study revealed the following: The girl demonstrated linguistic adaptations typical of child-directed speech in both Russian and German when interacting with her younger brother. However, these adaptations were not consistent across all linguistic categories analyzed, revealing some differences between the two languages. Notably, Katharina did not exhibit more child-directed speech features in one language over the other. Adaptive behavior was present in both Russian and German in categories such as MLU, MLU5, question constructions, and imperatives. In Russian, adaptation was also evident in coordinate constructions but not subordinate constructions, while the opposite pattern was observed in German.

Picturebooks Increase the Frequency and Diversity of Emotion Vocabulary in Children’s Language Environments: Modeling Potential Benefits to Emotional Literacy, with Pedagogical Resources

ABSTRACT Research Findings: This study examines the frequency and diversity of emotion vocabulary in children’s picturebooks, as well as its deviation from typical spoken language environments. We analyzed a corpus of 2146 transcripts of individuals reading picturebooks aloud on social media platforms, using an emotion-specific vocabulary list, and two emotion-related word lists: the Valence Aware Dictionary for Sentiment Reasoning (VADER) List, and the NRC Word-Emotion Lexicon Intensity Lists. Models of daily input assess how regular book reading impacts the diversity and quantity of emotion vocabulary in children’s language environments. The findings reveal that emotion vocabulary in children’s picturebooks is more diverse than found in typical samples of child-directed speech and that regular reading substantially increases exposure to emotion vocabulary in the language environment of children beyond their input from child-directed speech alone. The study underscores the significant role of regular picturebook reading in enriching children’s quantity and quality of emotion vocabulary exposure and the opportunities this may provide for emotional literacy development. Practice or Policy: The findings are supplemented with emotion vocabulary wordlists produced by the study and provided here (https://tinyurl.com/4pvcb8b4). These constitute new resources for supporting children’s emotion vocabulary acquisition during early education and development.

A longitudinal investigation of the acoustic properties of infant-directed speech from 6 to 18 months.

Caregivers often modulate their speech when interacting with infants, adapting a register that has been suggested to have attentional, affective and didactic purposes. The present preregistered study examined the longitudinal trajectories of a diverse range of acoustic features of infant-directed speech (IDS) and compared these with adult-directed speech (ADS), in Norwegian parents of 6- to 18-month-old infants. Sixty-nine families participated. Throughout five laboratory visits across one year, parents were recorded reading a picture-book to their infant (IDS) and an experimenter (ADS). The book was designed to tightly control for the linguistic content and context of speech between participants, timepoints and registers. Analyses of a total of 54 594 vowels and 22 958 phrases revealed, first, an overall effect of register: parents used higher pitch, wider pitch range, slower articulation rate, longer vowel duration and more variable and less distinct vowels in IDS than in ADS. Second, significant register-by-age interactions indicated that parents' IDS, compared with their ADS, featured wider pitch range, larger vowel space and shorter vowel duration in older as compared with younger infants, while pitch, articulation rate and vowel variability and distinctiveness remained relatively stable with age. Results are discussed in the context of the proposed functions of IDS.

Paternal and Maternal Speech at 3 Months Postpartum: An Exploratory Study on the Effect of Parental Role and Birth Weight.

Recent research highlights a growing interest in early interactions between fathers and their infants, acknowledging the significant influence these interactions have on developmental outcomes. However, there is a limited understanding of the specific characteristics of paternal infant-directed speech (IDS), especially in the context of premature birth. This study aimed to analyze the functional and morpho-syntactic features of paternal IDS to full-term (FT) and preterm (PT) infants at 3 months, comparing it with maternal communicative style. Additionally, the study explored the influence of the severity of preterm birth according to birth weight, further distinguishing between extremely low-birth-weight (ELBW) and very low-birth-weight (VLBW) infants. Seventy-one father-infant and mother-infant dyads (24 FT, 22 ELBW, 25 VLBW) were recruited at 3 months (corrected age for PTs). Parent-infant interactions were video recorded to assess lexical, syntactic, and functional aspects of paternal and maternal speech. Results revealed lower verbosity and lexical variability in paternal IDS compared to the maternal one. No differences were found between parents of the PT and FT groups. Overall, these findings could contribute to better understanding the patterns of parent-infant communications in both FT and PT dyads, confirming the importance of involving both mothers and fathers from the early stages of development.

Testing the relationship between preferences for infant-directed speech and vocabulary development: A multi-lab study.

From early on, infants show a preference for infant-directed speech (IDS) over adult-directed speech (ADS), and exposure to IDS has been correlated with language outcome measures such as vocabulary. The present multi-laboratory study explores this issue by investigating whether there is a link between early preference for IDS and later vocabulary size. Infants' preference for IDS was tested as part of the ManyBabies 1 project, and follow-up CDI data were collected from a subsample of this dataset at 18 and 24 months. A total of 341 (18 months) and 327 (24 months) infants were tested across 21 laboratories. In neither preregistered analyses with North American and UK English, nor exploratory analyses with a larger sample did we find evidence for a relation between IDS preference and later vocabulary. We discuss implications of this finding in light of recent work suggesting that IDS preference measured in the laboratory has low test-retest reliability.

Investigation of mothers' elicited infant-directed speech and singing for preterm infants.

Mother's voice is a salient auditory stimulus commonly experienced during early development; after birth, characteristic acoustic modulations of mothers' infant-directed speech (IDSpeech) and singing (IDSinging) contribute to neurodevelopment. For preterm infants, early separation leads to decreased exposure to mother's voice; the impact on maternal ability to produce IDSpeech/IDSinging and infant perception of mother's voice is unknown. Fifty mother/preterm-infant dyads were enrolled in this prospective cohort study. Forty-four mothers recorded Twinkle, Twinkle Little Star in coached adult-directed speech (ADSpeech), IDSpeech, and IDSinging. Between 34.0-36.9w CGA, infants underwent high-density EEG during exposure to their mother's voice recordings. Acoustic features of mothers' voice and infant cortical response were analyzed and correlated. Acoustic features of recorded maternal ADSpeech, IDSpeech, and IDSinging were significantly different. In 33 infants with EEG, mean fundamental frequency and speech production rate (SPR) variability correlated with infant responses to ADSpeech; SPR and SPR variability correlated with IDSpeech; SPR correlated with IDSinging. Correlations were found at differing scalp locations for speech versus singing. Mothers of hospitalized preterm infants differentially modulate their voice during coached recorded language; features can then be differentiated by their preterm infants thus presenting opportunities for targeted interventions when parents cannot be present. Mothers of preterm infants can record their voice with acoustically quantifiable characteristics of infant-directed singing and speech, even when not at their infant's bedside. Recorded adult- and infant-directed speech stimuli are differentially processed in the brains of hospitalized preterm infants. The ability for mothers to create acoustically-distinct infant-directed speech in the absence of their infant may be driven by coaching to achieve an approximated sense of connection with their infant.

Acoustic features of vocalizations in typically developing and autistic infants in the first year

We describe acoustic patterns across the five most prominent vocal types in typically developing infants (TD) and compare them with patterns in infants who develop autism (ASD) or a developmental disability (DD) not related to autism. Infant-directed speech (IDS) is a potentially important influence on such vocal acoustic patterns. Both acoustic patterns and effects of IDS are important for understanding the earliest origins of communication disorders. To compare duration, pitch and loudness of infant vocalizations for three groups of infants (TD, ASD, DD) in circumstances with high or low amounts of IDS. Two five-minute segments from each of 1259 all-day recordings across the first year were coded and acoustically analyzed for three groups of infants (130 TD, 44 ASD, 21 DD). Duration, mean fundamental frequency, and root mean square amplitude were determined for >162,000 infant utterances. Cries were longest and loudest, and vowel-like sounds were shortest of the five vocal types in all groups. TD infants showed significant alterations in vocal acoustics during periods of high IDS. Strong similarities in acoustic patterns occurred across the three groups, but only the TD group showed significant acoustic effects of IDS.