Infant Vocal Development Research Articles

Sensorimotor foundations of speech perception in infancy

The perceptual system for speech is highly organized from early infancy. This organization bootstraps young human learners' ability to acquire their native speech and language from speech input. Here, we review behavioral and neuroimaging evidence that perceptual systems beyond the auditory modality are also specialized for speech in infancy, and that motor and sensorimotor systems can influence speech perception even in infants too young to produce speech-like vocalizations. These investigations complement existing literature on infant vocal development and on the interplay between speech perception and production systems in adults. We conclude that a multimodal speech and language network is present before speech-like vocalizations emerge.

Mixed-Language Input and Infant Volubility: Friend or Foe?

Language mixing is a common feature of many bilingually-raised children's input. Yet how it is related to their language development remains an open question. The current study investigated mixed-language input indexed by observed (30-second segment) counts and proportions in day-long recordings as well as parent-reported scores, in relation to infant vocal activeness (i.e., volubility) when infants were 10 and 18 months old. Results suggested infants who received a higher score or proportion of mixed input in one-on-one social contexts were less voluble. However, within contexts involving language mixing, infants who heard more words were also the ones who produced more vocalizations. These divergent associations between mixed input and infant vocal development point for a need to better understand the causal factors that drive these associations.

The nature of infant vocal behaviour development between 8 and 17 months and its role in communication with mother

ABSTRACT Objective The tendency to vocalize toward objects is ubiquitous among young infants. However, little is known about the range of this tendency and its contribution to language development. Therefore, this longitudinal study objective was to explore the role of three forms of vocal behavior (vocalization, babbling, and speech) directed toward objects in communication with caregiver. Method To measure the spontaneous usage of vocal behaviors, 14 infants observed for 9 months and between the ages of 8 and 17 months, in their natural home environments once a month for a one-hour session with their mothers sitting nearby. Results A total of 1,961 vignettes were gathered and analyzed. It was found that, among the three forms of vocal behavior, object-directed vocalization was the most extensive at the age of 8 months. Repeated measures analysis showed that the frequency of each type of vocal output directed toward an object was associated with a rate of similar vocal output that was later directed toward the mother. Conclusions The discussion explains the change in vocal behavior rates and discusses the role of auditory feedback and contribution of the engagement with objects to explain the role of object-directed vocal outputs in later communication with others. KEY POINTS What is already known about this topic (1) Between the ages of 8 and 17 months, infants produce three types of vocal outputs:vocalisation (consonants and consonant-vowel repetition), babbling (baba, dada) and speech (one-word utterances). (2) Infants may direct their vocal outputs towards an object or a caregiver. (3) Vocal outputs play a key role in language development through auditory feedback when infants vocalise when alone and through caregivers’ verbal responses. What this topic adds (1) Vocalisation towards objects was the predominant tendency until infants approached their first birthday. (2) There is an association between the rate of object-directed vocalisation and later mother-directed vocalisation. (3) Object-directed vocalisation is an opportunity for rehearsing and mastering lingual forms that befit language development.

The onset of voice onset time: Measuring the emergent timing of laryngeal and oral gestures in early speech development

Voicing contrasts in stop consonants are predominantly signaled by manipulation of voice onset time (VOT), the relative timing of oral and laryngeal gestures responsible for the release of the oral constriction and the onset of phonation. VOT is usually measured from the acoustic signal and defined by the time between the stop consonant burst and the following glottal period. Although this works well in adult speech, the same measure can be problematic when applied to child vocalizations. Infant productions of closant-vocant sequences perceived as consonant-vowel syllables by adults often do not exhibit full closure and are voiced throughout. Traditional measures of VOT cannot then be employed, even though evidence from the acoustic signal can still be used to deduce the presence and timing of precursors of the oral and laryngeal gestures from which adult voicing contrasts later emerge. This study illustrates these issues using data derived from home audio recordings made monthly from birth to three years as part of a large-scale, longitudinal study of infant vocal development. New methods for measuring VOT are proposed, using the relative amplitude, frequency and phase of the harmonics in the acoustic signal to infer the timing of underlying articulatory gestures.

What Can We Perceive in Infant Vocalization?

Infant language development includes a complex social dynamic between adults and infants. Infant vocalization is a well-studied area of development, however adult perception of infant vocalization is less well-understood. The effectiveness of identifications made by adults may impact the social feedback loops that drive development. We collected data from a final sample of 460 undergraduate students who listened to brief (100-500 ms) audio clips of infant vocalization. Participants were asked to identify infants in the audio clips as male/female, English/non-English, and their approximate age. Participants were unable to determine the sex of the infant better than chance but showed better than chance performance for language and age, albeit with low accuracy. Exploratory follow-up analyses did not reveal an effect of caregiving experience, childcare experience, or participant gender on a participants’ ability to correctly identify the infant’s age, sex, or language. These findings suggest that adult caregivers, regardless of experience, are able to perceive elements of infant vocalizations that may influence responsiveness to infant vocal development. However, performance is far from perfect.

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.

Cross-cultural adaptation and psychometric assessment of a Persian version of Proctor's developmental vocal assessment protocol: Description of Persian infant vocal development

ObjectivesWith increasing recognition of the importance of pre-linguistic vocalization, and early intervention for children, proper protocols play an important role in documenting infants' progress and effects of early interventional programs. This study aimed to translate Proctor's Developmental Vocal Assessment Protocol into Persian, make cultural adaptations, assess Persian version of Developmental Vocal Assessment Protocol (P-DVAP)'s validity, internal consistency, and reliability, and provide a general perspective toward Persian infants' vocal behaviors. MethodsThis study was mainly conducted in reference to Beaton's guidelines included translation, synthesis, back-translation, expert committee review, & pretesting. Ten well-experienced speech and language therapists contributed in expert committee review. Mothers of 202 infants were interviewed by experienced speech and language therapists. ResultsExpert committee pointed out some difficulties that parents might have responding to P-DVAP. Such difficulties were sorted out in the P-DVAP applied for psychometric analysis. The Content Validity Index and Content Validity Ratio of P-DVAP were above 0.9. In test-retest reliability, Kappa coefficient was 0.6 and as the measure of inter item consistency, Kuder-Richardson-20 for each stage ranged from 0.1 to 0.5. Parents of typical infants reported variations in crying, vegetative sounds, laughing, prosody changes, babbling, approximants of meaningful words, and consonant-vowel structures as the most common vocal behaviors. The number of vocal behaviors reported for preterm infants after corrected gestational age was fewer than those of typical full-term infants. ConclusionThe P-DVAP is a comprehensive, reliable, valid, simple and clear protocol for clinical evaluation of Persian infants’ vocal behaviors.

Laryngeal Constriction Phenomena in Infant Vocalizations.

Purpose Instances of laryngeal constriction have been noted as a feature of infant vocal development. The purpose of this study was to directly evaluate the developmental occurrence of laryngeal constriction phenomena in infant crying, cooing, and babbling vocalizations. Method The cry and noncry vocalizations of 20 healthy term-born infants between the ages of 1 and 7 months were examined for instances of laryngeal constriction. Approximately 20,000 vocalization samples were acoustically evaluated, applying a combined visual (frequency spectra and melody curves) and auditory analysis; the occurrence of instances of different constriction phenomena was analyzed. Results Laryngeal constrictions were found during the production of cry and noncry vocalizations. The developmental pattern of constrictions for both vocalizations was charac-terized by an increase in constrictions followed by a decrease. During the age period of 3-5 months, when cry and noncry vocalizations were co-occurring, laryngeal constrictions were observed in 14%-22% of both types of vocalizations. An equal percentage of constrictions was found for both vocalizations at 5 months of age. Conclusions The findings confirm that the production of laryngeal constriction is a regularly occurring phenomenon in healthy, normally developing infants' spontaneous crying, cooing, and marginal babbling. The occurrence of constriction in both cry and noncry vocalizations suggests that an infant is exploiting physiological constraints of the sound-generating system for articulatory development during vocal exploration. These results lend support to the notion that the laryngeal articulator is the principal articulator that infants 1st start to control as they test and practice their phonetic production skills from birth through the 1st several months of life.

A retrospective video analysis of canonical babbling and volubility in infants later diagnosed with childhood apraxia of speech

ABSTRACT Canonical babbling and volubility are common indicators of infant vocal development. If either indicator falls below values found in typical infants, it may be an early signal of a developmental disorder. The aim of this retrospective investigation was to examine home videos for the frequency of canonical babbles, age of canonical babbling onset, and overall volubility of eight infants later diagnosed with childhood apraxia of speech and compare these data to that of six typically developing infants as well as four infants later diagnosed with a speech sound disorder. Results revealed the infants later identified with childhood apraxia of speech used fewer canonical babbles, had later onset of canonical babbling, and fewer syllables per minute (volubility) than the comparison groups. These results suggest that infants later diagnosed with childhood apraxia of speech may be less adept in vocal exploration and in the production of canonical babbles, perhaps due to fewer opportunities for mapping articulatory movement with auditory speech sound outcomes.

Utterance Duration as It Relates to Communicative Variables in Infant Vocal Development.

We aimed to provide novel information on utterance duration as it relates to vocal type, facial affect, gaze direction, and age in the prelinguistic/early linguistic infant. Infant utterances were analyzed from longitudinal recordings of 15 infants at 8, 10, 12, 14, and 16 months of age. Utterance durations were measured and coded for vocal type (i.e., squeal, growl, raspberry, vowel, cry, laugh), facial affect (i.e., positive, negative, neutral), and gaze direction (i.e., to person, to mirror, or not directed). Of the 18,236 utterances analyzed, durations were typically shortest at 14 months of age and longest at 16 months of age. Statistically significant changes were observed in utterance durations across age for all variables of interest. Despite variation in duration of infant utterances, developmental patterns were observed. For these infants, utterance durations appear to become more consolidated later in development, after the 1st year of life. Indeed, 12 months is often noted as the typical age of onset for 1st words and might possibly be a point in time when utterance durations begin to show patterns across communicative variables.

Ordinary Interactions Challenge Proposals That Maternal Verbal Responses Shape Infant Vocal Development.

This study tested proposals that maternal verbal responses shape infant vocal development, proposals based in part on evidence that infants modified their vocalizations to match mothers' experimentally manipulated vowel or consonant-vowel responses to most (i.e., 70%-80%) infant vocalizations. We tested the proposal in ordinary rather than experimentally manipulated interactions. Response-based proposals were tested in a cross-sectional study of 35 infants, ages 4 to 14 months, engaged in everyday interactions in their homes with their mothers using a standard set of toys and picture books. Mothers responded to 30% of infant vocalizations with vocal behaviors of their own, far fewer than experimentally manipulated response rates. Moreover, mothers produced comparatively few vowel and consonant-vowel models and responded to infants' vowel and consonant-vowel vocalizations in similar numbers. Infants showed little evidence of systematically modifying their vocal forms to match maternal responses in these interactions. Instead, consonant-vowel vocalizations increased significantly with infant age. Results obtained in ordinary interactions, rather than response manipulation, did not provide substantial support for response-based mechanisms of infant vocal development. Consistent with other research, however, consonant-vowel productions increased with infant age.

The Infant Monitor of Vocal Production: Simple Beginnings

The Infant Monitor of vocal Production (IMP) was conceived as an educational strategy to help parents understand the nature and pace of their baby's vocal development following neonatal diagnosis and amplification for hearing loss. The potential for other clinical applications emerged with use. The instrument presents as a series of parent–professional conversations that scaffold parent observation and evaluation of their baby's vocal development across the first 12 months of natural hearing ability/early device-aided hearing experience. A graphic representation of IMP results illustrates for parents and professionals the timeliness (or otherwise) of a baby's advancement through a hierarchy of vocal behaviours that demonstrate the emergence and integrity of an infant's audition-production loop—the mechanism whereby acuity of hearing guides nascent vocal productions to progressively ‘mirror’ the acoustic features of accessible speech. A pilot study showed that the IMP quantified typical infant vocal development as a function of chronological age/normal hearing experience (birth to 12 months). Further, it demonstrated that the instrument was sensitive to individual differences in rate of vocal development for infants, from birth to 12 months of device-assisted hearing age.

Maternal verbal responses to communication of infants at low and heightened risk of autism

This study investigates mothers' responses to infant communication among infants at heightened genetic risk (high risk) of autism spectrum disorder compared to infants with no such risk (low risk). A total of 26 infants, 12 of whom had an older sibling with autism spectrum disorder, were observed during naturalistic in-home interaction and semistructured play with their mothers at 13 and 18 months of age. Results indicate that overall, mothers of low-risk and high-risk infants were highly and similarly responsive to their infants' communicative behaviors. However, examination of infant vocal and gestural communication development together with maternal verbal responses and translations (i.e. verbally labeling a gesture referent) suggests that delays in early communication development observed among high-risk infants may alter the input that these infants receive; this in turn may have cascading effects on the subsequent development of communication and language.

Pre-first word vocalizations of infants with normal hearing and cochlear implants using the PRISE

The purpose of the present study was to compare the growth function of pre-first word vocalizations of infants with normal hearing (NH) to that of hearing-impaired (HI) infants pre- and post-cochlear implantation. Subjects included 163 infants between 0.5 and 20 months old with normal hearing and known normal development, and, 18 infants with cochlear implants (CI) who were implanted between 11 and 29 months. Pre-first word vocalization was assessed using the PRoduction Infant Scale Evaluation (PRISE) test. Parents of infants were interviewed using 11 probes reflecting known milestones in the infant's vocal development that lead to the first-word stage. NH infants show an exponential growth function of vocal development, which plateaus at approximately 13 months. HI infants show limited vocalizations before implantation regardless of age. After cochlear implant, PRISE scores of CI are in keeping with normal development of pre-first word vocalizations when plotted as a function of duration of implant use. The PRISE test contributes to evaluating the effectiveness of the habilitation process in general, and the efficacy of the implant device in particular. It can also alert to production problems not related to hearing loss thus allowing for early intervention.

Role of Infant Vocal Development in Candidacy for and Efficacy of Cochlear Implantation

Previous research has documented the importance of audition in the development of typical infant vocalization. Of particular interest is the development of canonical babbling, which is related to mastery of the timing elements of speech. Children with severe to profound hearing loss who use hearing aids have demonstrated both delayed and deviant canonical babbling. The vocal development of 12 children has been followed as they have been considered for cochlear implantation. Nine of these children have undergone implantation, and 5 of these children have been followed for more than 1 year after implantation. On average, canonical babbling emerged at 6.5 months after implantation. The time frame in which some children developed words was accelerated in terms of length of auditory experience as compared with normal-hearing peers. Mature oral-motor development is likely the primary contributing factor in this time course. One child who received a cochlear implant began to babble with hearing aids. It is not known whether normal canonical babbling is sufficient evidence on which to base candidacy decisions; however, our data suggest that children who produce canonical babbling maintain and build upon those skills after implantation.

Infant Vocal Development in a Dynamic Mother-Infant Communication System.

InfancyVolume 2, Issue 1 p. 87-109 Infant Vocal Development in a Dynamic Mother-Infant Communication System Hui-Chin Hsu, Corresponding Author Hui-Chin Hsu Department of Child and Family Development The University of GeorgiaDepartment of Child and Family Development, The University of Georgia, McPhaul Center, Athens, GA 30602-3622. E-mail: [email protected]Search for more papers by this authorAlan Fogel, Alan Fogel Department of Psychology University of UtahSearch for more papers by this author Hui-Chin Hsu, Corresponding Author Hui-Chin Hsu Department of Child and Family Development The University of GeorgiaDepartment of Child and Family Development, The University of Georgia, McPhaul Center, Athens, GA 30602-3622. E-mail: [email protected]Search for more papers by this authorAlan Fogel, Alan Fogel Department of Psychology University of UtahSearch for more papers by this author First published: 18 January 2010 https://doi.org/10.1207/S15327078IN0201_6Citations: 74AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Citing Literature Volume2, Issue1January 2001Pages 87-109 RelatedInformation

Infant vocal development during the first 6 months: speech quality and melodic complexity

Infant vocal development during the first 6 months: speech quality and melodic complexity

Infant vocal development during the first 6 months: speech quality and melodic complexity

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.

Relationship between Rhythmic Behavior and Canonical Babbling in Infant Vocal Development

The onset of canonical babbling (CB) is a landmark event in infants’ vocal development for spoken language. Previous research has suggested that the onset of CB coincides with the peak period of rhythmic activities. To examine this phenomenon in detail, 28 Japanese infants (14 girls, 14 boys) were observed longitudinally from the age of 5 to 9 months. In the experimental sessions, an audible or an inaudible rattle was placed into a hand of each tested infant. Then the number of times that the infant shook the rattle was counted. In the observational sessions, infants’ spontaneous rhythmic activities under natural conditions were observed. The result shows that rhythmic activities reached their peak around the onset of CB. When the infants began to babble, they shook whichever rattle was in their hand, regardless of its audibility. After this period, they shook the audible rattles more frequently than the inaudible ones. These findings suggest that, around the onset of CB, infants learn to control their motor activities based on auditory feedback.

Parents as Informants of their Child's Vocal and Early Language Development

Continuity in vocalization and language development was examined in the longitudinal study of 94 children. Parents observed their infant's vocal development with the help of a checklist during the first year of life and reported their lexical development by using the MacArthur Communicative Development Inventories (the CDIs) at the ages of 14 and 18 months. The Reynell Developmental Language Scales (the RDLS) were administered to the children in a laboratory setting at 18 months. The vocalization checklist revealed milestones of sound production which parents reported reliably and which were significantly related to the child's later language development. The continuity in vocal and language development was supported by a subgroup analysis, which showed that the early vocalizers had comprehended and produced significantly more words and suffixes than had the late vocalizers during the second year. The results also provided support to the concurrent and predictive validity of the CDIs. Significant correlat...