Infant vocal category exploration as a foundation for speech development.

Non-random exploration of infant speech-like vocalizations (e.g., squeals, growls, and vowel-like sounds or "vocants") is pivotal in speech development. This type of vocal exploration, often noticed when infants produce particular vocal types in clusters, serves two crucial purposes: it establishes a foundation for speech because speech requires formation of new vocal categories, and it serves as a basis for vocal signaling of wellness and interaction with caregivers. Despite the significance of clustering, existing research has largely relied on subjective descriptions and anecdotal observations regarding early vocal category formation. In this study, we aim to address this gap by presenting the first large-scale empirical evidence of vocal category exploration and clustering throughout the first year of life. We observed infant vocalizations longitudinally using all-day home recordings from 130 typically developing infants across the entire first year of life. To identify clustering patterns, we conducted Fisher's exact tests to compare the occurrence of squeals versus vocants, as well as growls versus vocants. We found that across the first year, infants demonstrated clear clustering patterns of squeals and growls, indicating that these categories were not randomly produced, but rather, it seemed, infants actively engaged in practice of these specific categories. The findings lend support to the concept of infants as manifesting active vocal exploration and category formation, a key foundation for vocal language.

Canonical babbling trajectories across the first year of life in autism and typical development.

LAY ABSTRACT: Our study examined how babies develop their ability to talk to help identify early signs of autism. We looked at babies' production of babbling with mature syllables across the first year of life. Babies usually start producing mature babbling at 7 months of age before they say their first words. Some studies have suggested that babies who are later diagnosed with autism produce this kind of babbling less frequently in their first year of life, but other studies have shown complicated outcomes. In this new study, we followed 44 autistic babies and compared them to 127 typically developing babies. We recorded the babies once every month, all day long, from the time that they were born until they were around 13 months old. Then, we studied their mature babbling from segments of these recordings. We found that the rate at which babies used mature babbling was lower in boys with autism, and higher in girls with autism, compared to babies without autism. This research helps us understand how babies with autism learn to talk. It also raises important questions about differences between boys and girls with autism. Our study can help us improve how scientists and clinicians can identify autism earlier, which could lead to better communication supports for autistic children and their families.

Foundations of Vocal Category Development in Autistic Infants.

The present study compared the infant's tendency in the first year of life to produce clusters of particular vocal types (squeals, vocants, and growls) in typically developing (TD) and autistic infants. Vocal clustering provides evidence of vocal category formation and may establish a foundation for speech development. Specifically, we compared the extent of vocal clustering across outcome groups and age groups. We also examined the associations between the extent of vocal clustering and later outcomes at 2 years within the autistic group. Randomly selected 5-min segments (27,153 5-min segments total) from 1293 all-day home recordings from 103 TD infants and 44 autistic infants across the first year were humancoded (about 9.75 h of data coded per infant on average) to derive vocal clustering patterns. Fisher's exact tests were used to compare the occurrence of squeals versus vocants, as well as growls versus vocants, across coded segments. Infants in both groups demonstrated clear clustering patterns of squeals and growls across all age groups. The extent of vocal clustering in the autistic group did not correlate significantly with later language, repetitive behavior, or autism severity outcomes. These findings highlight the robustness of the systematic production of vocal categories across the first year of life. The similarity of the clustering patterns in the TD and autistic groups suggests that vocal category formation through active infant vocal exploration is a robust feature of early speech development.

Infant vocal category exploration as a foundation for speech development.

Non-random exploration of infant speech-like vocalizations (e.g., squeals, growls, and vowel- like sounds or "vocants") is pivotal in speech development. This type of vocal exploration, often noticed when infants produce particular vocal types in clusters, serves two crucial purposes: it establishes a foundation for speech because speech requires formation of new vocal categories, and it serves as a basis for vocal signaling of wellness and interaction with caregivers. Despite the significance of clustering, existing research has largely relied on subjective descriptions and anecdotal observations regarding early vocal category formation. In this study, we aim to address this gap by presenting the first large-scale empirical evidence of vocal category exploration and clustering throughout the first year of life. We observed infant vocalizations longitudinally using all-day home recordings from 130 typically developing infants across the entire first year of life. To identify clustering patterns, we conducted Fisher's exact tests to compare the occurrence of squeals versus vocants, as well as growls versus vocants. We found that across the first year, infants demonstrated clear clustering patterns of squeals and growls, indicating that these categories were not randomly produced, but rather, it seemed, infants actively engaged in practice of these specific categories. The findings lend support to the concept of infants as manifesting active vocal exploration and category formation, a key foundation for vocal language.

Perspectives on the origin of language: Infants vocalize most during independent vocal play but produce their most speech-like vocalizations during turn taking.

A growing body of research emphasizes both endogenous and social motivations in human vocal development. Our own efforts seek to establish an evolutionary and developmental perspective on the existence and usage of speech-like vocalizations ("protophones") in the first year of life. We evaluated the relative occurrence of protophones in 40 typically developing infants across the second-half year based on longitudinal all-day recordings. Infants showed strong endogenous motivation to vocalize, producing vastly more protophones during independent vocal exploration and play than during vocal turn taking. Both periods of vocal play and periods of turn-taking corresponded to elevated levels of the most advanced protophones (canonical babbling) relative to periods without vocal play or without turn-taking. Notably, periods of turn taking showed even more canonical babbling than periods of vocal play. We conclude that endogenous motivation drives infants' tendencies to explore and display a great number of speech-like vocalizations, but that social interaction drives the production of the most speech-like forms. The results inform our previously published proposal that the human infant has been naturally selected to explore protophone production and that the exploratory inclination in our hominin ancestors formed a foundation for language.

The origin of language and relative roles of voice and gesture in early communication development.

Both vocalization and gesture are universal modes of communication and fundamental features of language development. The gestural origins theory proposes that language evolved out of early gestural use. However, evidence reported here suggests vocalization is much more prominent in early human communication than gesture is. To our knowledge no prior research has investigated the rates of emergence of both gesture and vocalization across the first year in human infants. We evaluated the rates of gestures and speech-like vocalizations (protophones) in 10 infants at 4, 7, and 11 months of age using parent-infant laboratory recordings. We found that infant protophones outnumbered gestures substantially at all three ages, ranging from >35 times more protophones than gestures at 3 months, to >2.5 times more protophones than gestures at 11 months. The results suggest vocalization, not gesture, is the predominant mode of communication in human infants in the first year.

Early Vocal Development in Tuberous Sclerosis Complex.

BACKGROUND: Our goal was to assess for the first time early vocalizations as precursors to speech in audio-video recordings of infants with tuberous sclerosis complex (TSC). METHODS: We randomly selected 40 infants with TSC from the TSC Autism Center of Excellence Research Network dataset. Using human observers, we analyzed 74 audio-video recordings within a flexible software-based coding environment. During the recordings, infants were engaged in developmental testing. We determined syllables per minute (volubility), the number of consonant-vowel combinations, such as 'ba' (canonical babbling), and the canonical babbling ratio (canonical syllables/total syllables) and compared the data with two groups of typically developing (TD) infants. One comparison group's data had come from a laboratory setting, while the other's had come from all-day Language Environment Analysis recordings at home. RESULTS: Compared with TD infants in laboratory and all-day Language Environment Analysis recordings, entry into the canonical babbling stage was delayed in the majority of infants with TSC, and the canonical babbling ratio was low (TD mean = 0.346, SE = 0.19; TSC mean = 0.117, SE = 0.023). Volubility level in infants with TSC was less than half that of TD infants (TD mean = 9.82, SE = 5.78; TSC mean = 3.99, SE = 2.16). CONCLUSIONS: Entry into the canonical stage and other precursors of speech development were delayed in infants with TSC and may signal poor language and developmental outcomes. Future studies are planned to assess prediction of language and developmental outcomes using these measures in a larger sample and in more precisely comparable recording circumstances.

Protophones, the precursors to speech, dominate the human infant vocal landscape.

Human infant vocalization is viewed as a critical foundation for vocal learning and language. All apes share distress sounds (shrieks and cries) and laughter. Another vocal type, speech-like sounds, common in human infants, is rare but not absent in other apes. These three vocal types form a basis for especially informative cross-species comparisons. To make such comparisons possible we need empirical research documenting the frequency of occurrence of all three. The present work provides a comprehensive portrayal of these three vocal types in the human infant from longitudinal research in various circumstances of recording. Recently, the predominant vocalizations of the human infant have been shown to be speech-like sounds, or 'protophones', including both canonical and non-canonical babbling. The research shows that protophones outnumber cries by a factor of at least five based on data from random-sampling of all-day recordings across the first year. The present work expands on the prior reports, showing the protophones vastly outnumber both cry and laughter in both all-day and laboratory recordings in various circumstances. The data provide new evidence of the predominance of protophones in the infant vocal landscape and illuminate their role in human vocal learning and the origin of language. This article is part of the theme issue 'Vocal learning in animals and humans'.

Social and endogenous infant vocalizations.

Research on infant vocal development has provided notable insights into vocal interaction with caregivers, elucidating growth in foundations for language through parental elicitation and reaction to vocalizations. A role for infant vocalizations produced endogenously, potentially providing raw material for interaction and a basis for growth in the vocal capacity itself, has received less attention. We report that in laboratory recordings of infants and their parents, the bulk of infant speech-like vocalizations, or "protophones", were directed toward no one and instead appeared to be generated endogenously, mostly in exploration of vocal abilities. The tendency to predominantly produce protophones without directing them to others occurred both during periods when parents were instructed to interact with their infants and during periods when parents were occupied with an interviewer, with the infants in the room. The results emphasize the infant as an agent in vocal learning, even when not interacting socially and suggest an enhanced perspective on foundations for vocal language.

Infant boys are more vocal than infant girls.

Although it is generally assumed females have a language advantage over males, Oller et al., studying all-day recordings of 100 infants, found that boys in the first year of life produced more speech-like vocalizations than girls and that the effect size was more than four times larger than the commonly reported female language advantage.

Preterm and full term infant vocalization and the origin of language.

How did vocal language originate? Before trying to determine how referential vocabulary or syntax may have arisen, it is critical to explain how ancient hominins began to produce vocalization flexibly, without binding to emotions or functions. A crucial factor in the vocal communicative split of hominins from the ape background may thus have been copious, functionally flexible vocalization, starting in infancy and continuing throughout life, long before there were more advanced linguistic features such as referential vocabulary. 2-3 month-old modern human infants produce "protophones", including at least three types of functionally flexible non-cry precursors to speech rarely reported in other ape infants. But how early in life do protophones actually appear? We report that the most common protophone types emerge abundantly as early as vocalization can be observed in infancy, in preterm infants still in neonatal intensive care. Contrary to the expectation that cries are the predominant vocalizations of infancy, our all-day recordings showed that protophones occurred far more frequently than cries in both preterm and full-term infants. Protophones were not limited to interactive circumstances, but also occurred at high rates when infants were alone, indicating an endogenous inclination to vocalize exploratorily, perhaps the most fundamental capacity underlying vocal language.

Registers in Infant Phonation.

The primary vocal registers of modal, falsetto, and fry have been studied in adults but not per se in infancy. The vocal ligament is thought to play a critical role in the modal-falsetto contrast but is still developing during infancy (Tateya and Tateya, 2015).41 Cover tissues are also implicated in the modal-fry contrast, but the low fundamental frequency (fo) cutoff of 70 Hz, shared between genders, suggests a psychoacoustic basis for the contrast. Buder, Chorna, Oller, and Robinson (2008)6 used the labels of "loft," "modal," and "pulse" for distinct vibratory regimes that appear to be identifiable based on spectrographic inspection of harmonic structure and auditory judgments in infants, but this work did not supply acoustic measurements to verify which of these nominally labeled regimes resembled adult registers. In this report, we identify clear transitions between registers within infant vocalizations and measure these registers and their transitions for fo and relative harmonic amplitudes (H1-H2). By selectively sampling first-year vocalizations, this manuscript quantifies acoustic patterns that correspond to vocal fold vibration types not previously cataloged in infancy. Results support a developmental basis for vocal registers, revealing that a well-developed ligament is not needed for loft-modal quality shifts as seen in harmonic amplitude measures. Results also reveal that a distinctively pulsatile register can occur in infants at a much higher fo than expected on psychoacoustic grounds. Overall results are consistent with cover tissues in infancy that are, for vibratory purposes, highly compliant and readily detached.

Auditory comprehension performance of college students with and without sport concussion on Computerized-Revised Token Test Subtest VIII.

AIM: Auditory comprehension (AC) and visually assessed cognitive functions were compared in early stage postconcussed (PC) athletes and healthy controls using the Subtest VIII of the Computerized-Revised Token Test (C-RTT) and Immediate Postconcussion Assessment and Cognitive Test (ImPACT). RESULTS: As compared with healthy controls (n = 30), PC subjects (n = 30) had significantly lower C-RTT efficiency scores (p = 0.018), and lower ImPACT scores; total symptom score (p = 0.000.), verbal memory (p = 0.000), visual memory (p = 0.000), visual motor speed (p = 0.000) and reaction time (p = 0.004) in this post-test only matched subject design. Impulse Control was not significant (p = 0.613). Multiple regression and ANOVA indicated an association with reaction time only (p = 0.012) for the PC subjects. After controlling for reaction time, a significant difference in AC remained. CONCLUSION: The relationship between AC and other visually assessed cognitive functions was inconsistent suggesting that the C-RTT and ImPACT assessed different functional systems.

Effects of Parental Interaction on Infant Vocalization Rate, Variability and Vocal Type.

Examination of infant vocalization patterns across interactive and noninteractive contexts may facilitate better understanding of early communication development. In the current study, with 24 infant-parent dyads, infant volubility increased significantly when parent interaction ceased (presenting a "still face," or SF) after a period of normal interaction ("face-to-face," or FF). Infant volubility continued at the higher rate than in FF when the parent re-engaged ("reunion," or RE). Additionally, during SF, the variability in volubility across infants decreased, suggesting the infants adopted relatively similar rates of vocalization to re-engage the parent. The pattern of increasing volubility in SF was seen across all of the most common speech-like vocal types of the first half-year of life (e.g., full vowels, quasivowels, squeals, growls). Parent and infant volubility levels were not significantly correlated. The findings suggest that by six months of age infants have learned that their vocalizations have social value and that changes in volubility can affect parental engagement.

Clinical test instrument development to identify and track recovery from concussion.

Over the past 25 years, neuropsychological assessment has been the prominent clinical method for evaluating neurocognitive functioning and monitoring recovery following mild traumatic brain injury (mTBI), or concussion. During this time, neuropsychological assessment of concussion has developed extensively starting from traditional paper-and-pencil tests to the more current computerized assessment batteries that are specifically designed for evaluating mTBI. Concussion assessment is complex and challenging due to the highly variable neurocognitive behavior and the wide range of diverse symptoms that follow an injury. Therefore, neuropsychological testing is only one component of a multifaceted, comprehensive assessment approach that also includes balance testing and symptom assessment. Because concussions may go undetected, more emphasis has been placed on objective and sensitive neuropsychological measures. Factors that could affect the validity of test performance include athletes not recognizing or intentionally hiding their symptoms or sandbagging their baseline performance. Due to the complex nature of identifying and evaluating mild head injuries, the purpose of this review is to discuss (1) the clinical use of neuropsychological testing in concussion management, (2) the methods used for evaluating and monitoring recovery following concussion, (3) the characteristics of current assessment instruments, and (4) additional clinical factors and approaches for concussion assessment and management.