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The quest for the origins of language is a diverse enterprise, where research from a variety of disciplines brings area-specific ideas and area-specific terminology to bear. This variety often results in misunderstandings and misconceptions about communication in various species. In the present paper, we argue for focus on emotional systems as the primary motivators for social signals in animals in general. This focus can help resolve discrepancies of interpretation among different areas of inquiry and can illuminate distinctions among different social signals as well as their phylogenetic origins in animals and especially in humans. We advocate, following Jaak Panksepp, a view wherein the Seeking System, the endogenous tendency to search and explore, is the most fundamental emotional motivation. The Seeking System forms the basis for flexible, voluntary, and exploratory control of motor systems and makes much of learning possible. The relative lack of vocal learning and expression in nonhuman primates contrasted with extensive vocal learning and expression in humans began, we propose, with the evolution in ancient hominins of a necessary foundation for the many subsequent capabilities required for language. That foundation was, according to the reasoning, naturally selected in the form of neurological connections between the Seeking System and mechanisms of glottal/phonatory control. The new connections allowed ancient hominins to develop flexible, endogenous vocal fitness signals produced at very high rates and including large numbers of discrete syllables, recombinable to form syllable combinations with many prosodic variations. The increasing sociality of hominins supported evolution of massive expansion in the utilization of these flexible vocal forms to allow development of words and sentences. [ABSTRACT FROM AUTHOR]

The quest for the origins of language is a diverse enterprise, where research from a variety of disciplines brings area-specific ideas and area-specific terminology to bear. This variety often results in misunderstandings and misconceptions about communication in various species. In the present paper, we argue for focus on emotional systems as the primary motivators for social signals in animals in general. This focus can help resolve discrepancies of interpretation among different areas of inquiry and can illuminate distinctions among different social signals as well as their phylogenetic origins in animals and especially in humans. We advocate, following Jaak Panksepp, a view wherein the Seeking System, the endogenous tendency to search and explore, is the most fundamental emotional motivation. The Seeking System forms the basis for flexible, voluntary, and exploratory control of motor systems and makes much of learning possible. The relative lack of vocal learning and expression in nonhuman primates contrasted with extensive vocal learning and expression in humans began, we propose, with the evolution in ancient hominins of a necessary foundation for the many subsequent capabilities required for language. That foundation was, according to the reasoning, naturally selected in the form of neurological connections between the Seeking System and mechanisms of glottal/phonatory control. The new connections allowed ancient hominins to develop flexible, endogenous vocal fitness signals produced at very high rates and including large numbers of discrete syllables, recombinable to form syllable combinations with many prosodic variations. The increasing sociality of hominins supported evolution of massive expansion in the utilization of these flexible vocal forms to allow development of words and sentences.

Infant vocalization plays a pivotal role in communicating infant mood to parents and thereby motivating parenting responses. Although many psychological and neural responses to infant vocalization have been reported, few studies have examined maternal approach-avoidance behavior in response to infant vocalization. Thus, this research sought to determine how infant emotional vocalization affects maternal behavior. Twenty mothers participated in this behavioral study, all of whom had infants of 24 months old or less. In the experiment, they stood on a Balance Board that collected real-time data regarding center of pressure (COP), while listening to a series of infant vocalizations including cry, laugh, and babbling. They then listened to the same vocalizations for a second time and rated their felt emotions in response to each vocalization. The participants demonstrated significant postural movements of approaching in response to cry stimuli or to stimuli regarded as highly urgent. In contrast, they demonstrated postural movement of avoidance in response to laugh vocalization. These findings suggest that parenting behavior in response to infant emotional vocalization is regulated not by the pleasant-unpleasant axis but by the urgency of the stimulus.

Infant vocalization plays a pivotal role in communicating infant mood to parents and thereby motivating parenting responses. Although many psychological and neural responses to infant vocalization have been reported, few studies have examined maternal approach-avoidance behavior in response to infant vocalization. Thus, this research sought to determine how infant emotional vocalization affects maternal behavior. Twenty mothers participated in this behavioral study, all of whom had infants of 24 months old or less. In the experiment, they stood on a Balance Board that collected real-time data regarding center of pressure (COP), while listening to a series of infant vocalizations including cry, laugh, and babbling. They then listened to the same vocalizations for a second time and rated their felt emotions in response to each vocalization. The participants demonstrated significant postural movements of approaching in response to cry stimuli or to stimuli regarded as highly urgent. In contrast, they demonstrated postural movement of avoidance in response to laugh vocalization. These findings suggest that parenting behavior in response to infant emotional vocalization is regulated not by the pleasant-unpleasant axis but by the urgency of the stimulus. [ABSTRACT FROM AUTHOR]

Parental communication styles and language usage may undergo changes during the course of child development, exhibiting variations across language backgrounds and cultures. This study aimed to explore how infant-parent interactions within Korean-speaking environments evolve over time through meticulous coding of day-long home audio recordings. The study examined whether the ratio and types of parental verbal responses vary based on infants' age and vocalization types. A total of 16 infants and their parents participated in all-day home recordings using the Language Environment Analysis (LENA) system. The recordings were conducted in two rounds per family when the infants were aged 9–11 months and 12–14 months, with a three-month gap between each round. The frequency and types of infant vocalizations were analyzed and the contingency and types of parental verbal responsiveness were determined based on semantic and phonetic connection, as well as temporal appropriateness. The results showed that parents did not verbally respond to approximately 50 % of the infant vocalizations in the natural home environment. However, parents' lack of verbal responses decreased significantly, and their contingent responses increased significantly with infant age. Parents were also not selectively responsive to infants' canonical vocalizations over non-canonical vocalizations. Nevertheless, parents demonstrated a higher frequency of responses that were not only linguistically meaningful but also socially appropriate and contextually relevant to infants' vocalizations as infants developed, which may play a significant role in scaffolding speech and language development. • Infants gradually produced syllabic vocalizations in their linguistic environment. • Parents provide differential responses to vocalizations according to infant age. • Parental responses are specific to particular vocal types at specific period. • Parental differential feedback plays a significant role for language development. [ABSTRACT FROM AUTHOR]

Introduction: The introduction of neonatal hearing screening and the increasingly early age at which children can receive a cochlear implant has intensified the need for a validated questionnaire to assess the speech production of children aged 0‒18. Such a questionnaire has been created, the LittlEARS® Early Speech Production Questionnaire (LEESPQ). This study aimed to validate a second, revised edition of the LEESPQ.Methods and materials: Questionnaires were returned for 362 children with normal hearing. Completed questionnaires were analysed to determine if the LEESPQ is reliable, prognostically accurate, internally consistent, and if gender or multilingualism affects total scores.Results: Total scores correlated positively with age. The LEESPQ is reliable, accurate, and consistent, and independent of gender or lingual status. A norm curve was created.Discussion: This second version of the LEESPQ is a valid tool to assess the speech production development of children with normal hearing, aged 0‒18, regardless of their gender. As such, the LEESPQ may be a useful tool to monitor the development of paediatric hearing device users.Conclusion: The second version of the LEESPQ is a valid instrument for assessing early speech production of children aged 0‒18 months. [ABSTRACT FROM AUTHOR]

Seeking roots of language, we probed infant facial expressions and vocalizations. Both have roles in language, but the voice plays an especially flexible role, expressing a variety of functions and affect conditions with the same vocal categories—a word can be produced with many different affective flavors. This requirement of language is seen in very early infant vocalizations. We examined the extent to which affect is transmitted by early vocal categories termed “protophones” (squeals, vowel-like sounds, and growls) and by their co-occurring facial expressions, and similarly the extent to which vocal type is transmitted by the voice and co-occurring facial expressions. Our coder agreement data suggest infant affect during protophones was most reliably transmitted by the face (judged in video-only), while vocal type was transmitted most reliably by the voice (judged in audio-only). Voice alone transmitted negative affect more reliably than neutral or positive affect, suggesting infant protophones may be used especially to call for attention when the infant is in distress. By contrast, the face alone provided no significant information about protophone categories. Indeed coders in VID could scarcely recognize the difference between silence and voice when coding protophones in VID. The results suggest that partial decoupling of communicative roles for face and voice occurs even in the first months of life. Affect in infancy appears to be transmitted in a way that audio and video aspects are flexibly interwoven, as in mature language.

Functional flexibility, as manifest in the use of any word or sentence to express different affective valences on different occasions, is required in linguistic communication and can be said to be an infrastructural property of language. Early infant vocalizations (protophones), believed to be precursors to speech, occur in the first month and are functionally different from non-speech-like signals (e.g., cries and laughs). Oller et al. (2013) showed that infants by 3 months used three different protophone types with a full range of affect as manifest in facial expression, from positive to neutral to negative. These differences in affect were also shown to correspond to different illocutionary functions, unlike fixed signals, or vegetative sounds, which showed functional rigidity. The present study investigated whether infants show functional flexibility in protophones even earlier than the ages studied by Oller et al. (2013). Data were obtained from 6 infants across the first 3 months. Results showed that as early as the first month, infant protophones were already accompanied by variable facial affect valences and continued to be affectively flexible at the later ages. The present study thus documents the very early emergence of an infrastructural property of human communication. [ABSTRACT FROM AUTHOR]

Objective Universal Newborn Hearing Screening programs, now instituted throughout the German-speaking countries, allow hearing loss to be detected and treated much earlier than ever before. With this earlier detection, arises the need for tools fit for assessing the very early speech and language production development of today's younger (0–18 month old) children. We have created the LittlEARS ® Early Speech Production Questionnaire, with the aim of meeting this need. Methods 600 questionnaires of the pilot version of the LittlEARS ® Early Speech Production Questionnaire were distributed to parents via pediatricians' practices, day care centers, and personal contact. The completed questionnaires were statistically analyzed to determine their reliability, predictive accuracy, internal consistency, and to what extent gender or unilingualism influenced a child's score. Further, a norm curve was generated to plot the children's increased expected speech production ability with age. Results Analysis of the data from the 352/600 returned questionnaires revealed that scores on LittlEARS ® Early Speech Production Questionnaire correlate positively with a child's age, with older children scoring higher than do younger children. Further, the questionnaire has a high measuring reliability, high predictability, high unidemensionality of scale, and is not significantly gender or uni-/multilingually biased. A norm curve for expected development with age was created. Conclusions The LittlEARS ® Early Speech Production Questionnaire (LEESPQ) is a valid tool for assessing the most important milestones in very early development of speech and language production of German language children with normal hearing aged 0–18 months old. The questionnaire is a potentially useful tool for long-term infant screening and follow-up testing and for children with normal hearing and those who would benefit from or use hearing devices. [ABSTRACT FROM AUTHOR]

The pairing of dynamical systems theory and complexity science brings novel concepts and methods to the study of infant motor development. Accordingly, this longitudinal case study presents a new approach to characterizing the dynamics of infant limb and vocalization behaviors. A single infant’s vocalizations and limb movements were recorded from 51-days to 305-days of age. On each recording day, accelerometers were placed on all four of the infant’s limbs and an audio recorder was worn on the child’s chest. Using nonlinear time series analysis methods, such as recurrence quantification analysis and Allan factor, we quantified changes in the stability and multiscale properties of the infant’s behaviors across age as well as how these dynamics relate across modalities and effectors. We observed that particular changes in these dynamics preceded or coincided with the onset of various developmental milestones. For example, the largest changes in vocalization dynamics preceded the onset of canonical babbling. The results show that nonlinear analyses can help to understand the functional co-development of different aspects of infant behavior.

Sound moves us. Nowhere is this more apparent than in our responses to genuine emotional vocalisations, be they heartfelt distress cries or raucous laughter. Here, we present perceptual ratings and a description of a freely available, large database of natural affective vocal sounds from human infants, adults and domestic animals, the Oxford Vocal (OxVoc) Sounds database. This database consists of 173 non-verbal sounds expressing a range of happy, sad and neutral emotional states. Ratings are presented for the sounds on a range of dimensions from a number of independent participant samples. Perceptions related to valence, including distress, vocaliser mood, and listener mood are presented in Study 1. Perceptions of the arousal of the sound, listener motivation to respond and valence (positive, negative) are presented in Study 2. Perceptions of the emotional content of the stimuli in both Study 1 and Study 2 were consistent with the predefined categories (e.g., laugh stimuli perceived as positive). While the adult vocalisations received more extreme valence ratings, rated motivation to respond to the sounds was highest for the infant sounds. The major advantages of this database are the inclusion of vocalisations from naturalistic situations, which represent genuine expressions of emotion, and the inclusion of vocalisations from animals and infants, providing comparison stimuli for use in cross-species and developmental studies. The associated website provides a detailed description of the physical properties of the each sound stimulus along with cross-category descriptions.

This study investigated the reduplicated, or repetitive vocalizations of hearing infants and infants with profound hearing loss with and without cochlear implants using a new measure of repetition in order to address questions not only about the effects of cochlear implantation on repetitive babbling, but also about the reason repetitive vocalizations occur at all and why they emerge around 7 or 8 months of age in hearing infants. Participants were 16 infants with profound hearing loss and 27 hearing infants who participated at a mean age of 9.9 months and/or a mean age of 17.7 months. Mean age at cochlear implantation for infants with profound hearing loss was 12.9 months, and mean duration of implant use was 4.2 months. The data show that before cochlear implantation, repetitive vocalizations were rare. However, 4 months after cochlear implant activation, infants with hearing loss produced both repetitive vocalizations and repetitions per vocalization at levels commensurate with their hearing peers. The results support the hypothesis that repetition emerges as a means of vocal exploration during the time when hearing infants (and infants with cochlear implants) form auditory–motor representations and neural connections between cortical areas active in syllable production and syllable perception, during the transition from nonlinguistic to linguistic vocalization. [ABSTRACT FROM AUTHOR]

Summary Objective To investigate frequency measurement of the first three formants of the seven oral Brazilian Portuguese vowels of healthy children aged 4–8 years. Methods Two hundred seven children of both genders were selected by oral expression screening and perceptive-auditory analysis. They were separated into four age groups (G1, G2, G3, and G4) and by gender. The voice signals were obtained from key sentence utterance and segments of the seven Brazilian Portuguese oral vowels in tonic position used to estimate formant frequency measurement. Software Praat was used to for processing the recordings. Results Findings were presented by mean values of each of the investigated parameters. A rate of 61.90% of statistically significant differences between genders was found, and when analyzing the age groups and genders, we observed that 65 of the 84 items studied (seven vowels × three formant frequencies × four groups) had higher frequencies of formants for girls. There was a decrease in the frequencies values of the first three formants with age. The results recommended grouping of G1 and G2, and they showed a clear difference between this new formed group and G4. In the age groups of 5-year old to 6 years 11 months (G2 and G3) and 6-year old to 7 years 11 months (G3 and G4), there were statistically significant changes that were random for parameter and vowel. There was a decrease in the frequencies values of the first three formants with age. Conclusion Formant frequencies showed a tendency to differentiate genders and their absolute values were in general higher in girls. Age increases showed decreases in formant frequencies. Tests for statistical differences led to grouping of G1 and G2 and a clear difference between this new formed group and G4. The comparison between G2 and G3 and G3 and G4 showed random changes. The changes during this age period (5-year old to 7 years 11 months) were attributed to a transition stage of acoustic measurements in children. As formant frequencies vary according to structural and postural aspects of the vocal tract and speech organs, their study in healthy children contributes for the understanding of the development of the pediatric phonation system, in addition to offering a reference data set for future studies of children with vocal disorders that can potentially impact the resonance system. [ABSTRACT FROM AUTHOR]

The purpose of this study was to explore developmental changes, in terms of spectral fluctuations and temporal periodicity with Japanese- and English-learning infants. Three age groups (15, 20, and 24 months) were selected, because infants diversify phonetic inventories with age. Natural speech of the infants was recorded. We utilized a critical-band-filter bank, which simulated the frequency resolution in adults’ auditory periphery. First, the correlations between the critical-band outputs represented by factor analysis were observed in order to see how the critical bands should be connected to each other, if a listener is to differentiate sounds in infants’ speech. In the following analysis, we analyzed the temporal fluctuations of factor scores by calculating autocorrelations. The present analysis identified three factors observed in adult speech at 24 months of age in both linguistic environments. These three factors were shifted to a higher frequency range corresponding to the smaller vocal tract size of the infants. The results suggest that the vocal tract structures of the infants had developed to become adult-like configuration by 24 months of age in both language environments. The amount of utterances with periodic nature of shorter time increased with age in both environments. This trend was clearer in the Japanese environment.

The motivation for infants' non-word vocalizations in the second half of the first year of life and later is unclear. This study of hearing infants and infants with profound hearing loss with and without cochlear implants addressed the hypothesis that vocalizations are primarily motivated by auditory feedback. Early access to cochlear implants has created unique conditions of auditory manipulation that permit empirical tests of relations between auditory perception and infant behavior. Evidence from two separate tests of the research hypothesis showed that, before cochlear implantation, infants with profound hearing loss vocalized significantly less often than hearing infants; however, soon after cochlear implantation, they vocalized at levels commensurate with hearing peers. In contrast, vocal behaviors that are typically considered reflexive or emotion-based signals (e.g., crying) were infrequent overall and did not vary with auditory access. These results support the hypothesis that auditory feedback is a critical component motivating early vocalization frequency. [ABSTRACT FROM AUTHOR]

The pairing of dynamical systems theory and complexity science brings novel concepts and methods to the study of infant motor development. Accordingly, this longitudinal case study presents a new approach to characterizing the dynamics of infant limb and vocalization behaviors. A single infant's vocalizations and limb movements were recorded from 51-days to 305-days of age. On each recording day, accelerometers were placed on all four of the infant's limbs and an audio recorder was worn on the child's chest. Using nonlinear time series analysis methods, such as recurrence quantification analysis and Allan factor, we quantified changes in the stability and multiscale properties of the infant's behaviors across age as well as how these dynamics relate across modalities and effectors. We observed that particular changes in these dynamics preceded or coincided with the onset of various developmental milestones. For example, the largest changes in vocalization dynamics preceded the onset of canonical babbling. The results show that nonlinear analyses can help to understand the functional co-development of different aspects of infant behavior. [ABSTRACT FROM AUTHOR]

Sound moves us. Nowhere is this more apparent than in our responses to genuine emotional vocalizations, be they heartfelt distress cries or raucous laughter. Here, we present perceptual ratings and a description of a freely available, large database of natural affective vocal sounds from human infants, adults and domestic animals, the Oxford Vocal (OxVoc) Sounds database. This database consists of 173 non-verbal sounds expressing a range of happy, sad, and neutral emotional states. Ratings are presented for the sounds on a range of dimensions from a number of independent participant samples. Perceptions related to valence, including distress, vocalizer mood, and listener mood are presented in Study 1. Perceptions of the arousal of the sound, listener motivation to respond and valence (positive, negative) are presented in Study 2. Perceptions of the emotional content of the stimuli in both Study 1 and 2 were consistent with the predefined categories (e.g., laugh stimuli perceived as positive). While the adult vocalizations received more extreme valence ratings, rated motivation to respond to the sounds was highest for the infant sounds. The major advantages of this database are the inclusion of vocalizations from naturalistic situations, which represent genuine expressions of emotion, and the inclusion of vocalizations from animals and infants, providing comparison stimuli for use in cross-species and developmental studies. The associated website provides a detailed description of the physical properties of each sound stimulus along with cross-category descriptions. [ABSTRACT FROM AUTHOR]

Abstract: Vocal motor development in infancy provides a crucial foundation for language development. Some significant early accomplishments include learning to control the process of phonation (the production of sound at the larynx) and learning to produce the sounds of one’s language. Previous work has shown that social reinforcement shapes the kinds of vocalizations infants produce. We present a neural network model that provides an account of how vocal learning may be guided by reinforcement. The model consists of a self-organizing map that outputs to muscles of a realistic vocalization synthesizer. Vocalizations are spontaneously produced by the network. If a vocalization meets certain acoustic criteria, it is reinforced, and the weights are updated to make similar muscle activations increasingly likely to recur. We ran simulations of the model under various reinforcement criteria and tested the types of vocalizations it produced after learning in the different conditions. When reinforcement was contingent on the production of phonated (i.e. voiced) sounds, the network’s post-learning productions were almost always phonated, whereas when reinforcement was not contingent on phonation, the network’s post-learning productions were almost always not phonated. When reinforcement was contingent on both phonation and proximity to English vowels as opposed to Korean vowels, the model’s post-learning productions were more likely to resemble the English vowels and vice versa. [Copyright &y& Elsevier]

Abstract: Recurrent hypoglycemia is a common problem among infants and children that is associated with several metabolic disorders and insulin-dependent diabetes mellitus. Although studies have reported a relationship between a history of juvenile hypoglycemia and psychological health problems, the direct effects of recurrent moderate hypoglycemia have not been fully determined. Thus, in this study, we used an animal model to examine the effects of recurrent hypoglycemia during the juvenile period on affective, social, and motor function (assessed under euglycemic conditions) across development. To model recurrent hypoglycemia, rats were administered 5U/kg of insulin or saline twice per day from postnatal day (P)10 to P19. Body weight gain was retarded in insulin-treated rats during the treatment period, but recovered by the end of treatment. However, insulin-treated rats displayed increases in affective reactivity that emerged early during treatment and persisted after treatment into early adulthood. Specifically, insulin-treated pups showed increased maternal separation-induced vocalizations as infants, and an exaggerated acoustic startle reflex as juveniles and young adults. Moreover, young adult rats with a history of recurrent juvenile hypoglycemia exhibited increased fear-potentiated startle and increases in behavioral and hormonal responses to restraint stress. Some of these effects were sex-dependent. The changes in affective behavior in insulin-exposed pups were accompanied by decreases in adolescent social play behavior. These results provide evidence that recurrent, transient hypoglycemia during juvenile development can lead to increases in fear-related behavior and stress reactivity. Importantly, these phenotypes are not reversed with normalization of blood glucose and may persist into adulthood. [Copyright &y& Elsevier]

Abstract: Vocal babbling involves production of rhythmic sequences of a mouth close–open alternation giving the perceptual impression of a sequence of consonant–vowel syllables. Petitto and co-workers have argued vocal babbling rhythm is the same as manual syllabic babbling rhythm, in that it has a frequency of 1 cycle per second. They also assert that adult speech and sign language display the same frequency. However, available evidence suggests that the vocal babbling frequency approximates 3 cycles per second. Both adult spoken language and sign language show higher frequencies than babbling in their respective modalities. No information is currently available on the basic rhythmic parameter of intercyclical variability in either modality. A study of reduplicative babbling by 4 infants and 4 adults producing reduplicated syllables confirms the 3 per second vocal babbling rate, as well as a faster rate in adults, and provides new information on intercyclical variability. [Copyright &y& Elsevier]

Summary: Infant phonation is highly variable in many respects, including the basic vibratory patterns by which the vocal tissues create acoustic signals. Previous studies have identified the regular occurrence of nonmodal phonation types in normal infant phonation. The glottis is like many oscillating systems that, because of nonlinear relationships among the elements, may vibrate in ways representing the deterministic patterns classified theoretically within the mathematical framework of nonlinear dynamics. The infant''s preverbal vocal explorations present such a variety of phonations that it may be possible to find effectively all the classes of vibration predicted by nonlinear dynamic theory. The current report defines acoustic criteria for an important subset of such vibratory regimes, and demonstrates that analysts can be trained to reliably use these criteria for a classification that includes all instances of infant phonation in the recorded corpora. The method is thus internally comprehensive in the sense that all phonations are classified, but it is not exhaustive in the sense that all vocal qualities are thereby represented. Using the methods thus developed, this study also demonstrates that the distributions of these phonation types vary significantly across sessions of recording in the first year of life, suggesting developmental changes. The method of regime classification is thus capable of tracking changes that may be indicative of maturation of the mechanism, the learning of categories of phonatory control, and the possibly varying use of vocalizations across social contexts. [Copyright &y& Elsevier]

Most mammalian infants vocalize when isolated. The vocalization promotes caregiver proximity, which is critical to survival. If, before isolation, a rat pup has contact with its dam, its isolation vocalization rate is increased (maternal potentiation) relative to isolation preceded only by littermate contact. Prior work showed that systemic administration of a D2 receptor agonist blocks maternal potentiation at doses that do not alter baseline vocalization. In this study, infusion of quinpirole (2 µg/side) into the nucleus accumbens also blocks maternal potentiation. Infusion of the accumbens with the D2 antagonist raclopride (4 µg/side) prevents systemic quinpirole from blocking potentiation. Quinpirole infusion in the dorsal striatum did not affect maternal potentiation and infusion of raclopride in the dorsal striatum did not reverse the block of maternal potentiation by systemic quinpirole. Vocalization results after a second vehicle infusion on a given day are no different than the results following an initial vehicle infusion, so experimental design can not account for the effects of drug infusions. Because activity level was increased by both dorsal and ventral striatum infusions, activity level can not account for the results. [ABSTRACT FROM AUTHOR]

Purpose: Onset of canonical babbling by 10 months of age is surprisingly robust in infancy, suggesting that there must be deep biological forces that keep the development of this key vocal capability on course. This study further evaluated the robustness of canonical babbling and other aspects of prelinguistic vocal development. Method: Longitudinal observation was conducted on 4 infants who were at risk for abnormal vocal development because of bilateral moderate-to-severe sensorineural hearing loss and additional risk factors for developmental delay. Results: Two of the infants were delayed in the onset of canonical babbling and showed greater fluctuation in canonical babbling ratios following its onset than did typically developing infants. On the same measures, the remaining 2 infants were within normal limits, although their age of onset for canonical babbling was later than the mean for typically developing infants. Volubility was not notably different from typically developing infants. Differences from typically developing infants were, however, observed in proportions of various prelinguistic syllable types produced across time. Conclusion: Results provided further evidence of robustness of canonical babbling and indicated the need for a large parametric study evaluating effects of varying degrees of hearing loss and other risk factors on vocal development. [ABSTRACT FROM AUTHOR]

Analysis of coordinated interpersonal timing has become an important tool for the study of infant-adult, peer, and marital interactions. Past research suggests that social coordination is informative about the quality of the caregiver-child social relationship. Does infant experience of certain types of coordination and pattern in early social interactions with caregivers predict better cognitive and social developmental outcomes? The recent monograph “Rhythms of dialogue in infancy” (Jaffe, Beebe, Feldstein, Crown, & Jasnow, 2001) provides the strongest evidence to date that it does. Moderately coordinated social interactions in early infancy predicted the most favorable developmental outcomes, and degree of coordination was influenced by contextual factors such as setting and nature of the relationship between the infant and its social interaction partner. This study provides a model for future research in this area and points toward important questions for future research on infant-caregiver social interactions. [ABSTRACT FROM AUTHOR]

The early development of infant non-distress vocalizations was investigated in this study. Thirteen infants, from 4 to 24 weeks of age, and their mothers were observed weekly in a face-to-face interaction situation. The speech quality (syllabic versus vocalic) and melodic complexity (simple versus complex) of infant vocalizations were coded independently. Based on speech quality and melodic complexity, four types of infant non-distress vocalizations were categorized: simple and complex syllabic (speech-like) vocalizations as well as simple and complex vocalic (non-speech-like) vocalizations. Results showed that complex syllabic sounds were of longer duration and complex vocalic sounds were less frequent than the other types of vocalizations. Curvilinear developmental trends were found in the rate of simple vocalic sounds and in the mean duration of complex syllabic sounds. Furthermore, before 4 months of age, vocalic sounds were more likely to be associated with simple melodic contours, after which syllabic sounds were more likely to be associated with complex melodic contours. A dynamic systems perspective on the early development of infant vocalization is discussed. Copyright © 2000 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]