Infant Vocalizations Research Articles

Singing development as a sensorimotor interaction problem.

ABSTRACT - Singing a ubiquitous human behavior and plays a significant role in human culture and socialization. Research on children's singing has focused on music instruction techniques for developing singers, yet little known about the developmental mechanisms underlying singing acquisition. Recently, Berkawska and Dalla Bella (2009a) proposed a sensorimotor loop model of singing to explain poor singing ability in the adult population. Here, we review the literature on the development of singing during childhood in the context of the sensorimotor loop model of singing. KEYWORDS - singing, development, children, auditory perception, motor function Singing widely regarded as a universal human behavior (Dowling, 1984; Welch, 1994) that serves a number of important social functions. Singing an effective means of transmitting cultural knowledge and social customs (Chatwin, 1987; Cong-HuyenTon-Nu, 1979). Singing also used to ease the pressures of everyday life. For example, many workers use song to accompany work activities, especially those requiring the synchronization of repetitive movements (Cong-Huyen-Ton-Nu, 1979; Keil, 1979). Singing often an important part of courtship, and it has been proposed that robust musical calls may signal the possession of healthy, appealing genes to prospective mates (e.g., Huron, 2001). In general, singing can promote social cohesion, reinforce cherished values and ideals, foster shared identity, and promote emotional contagion (Booth, 1981; Peretz, 2006). Finally, singing plays a critical role in child rearing and the caregiver-infant bond. Lullabies and playsongs are found in all known cultures, suggesting that they serve an important function in maternal child care (Trehub, 2000; Trehub & Trainor, 1998). Despite the importance of singing in both human development and human culture, there has been relatively little empirical research on the acquisition of singing during childhood. Singing thought to emerge spontaneously without formal instruction during early child development (Dalla Bella, Giguere, & Peretz, 2007) and many studies over the last 30 years have documented a relatively orderly progression of the acquisition of specific singing abilities during childhood (e.g., see Welch, 2006 for a review). However, the developmental mechanisms underlying singing acquisition during childhood are still not well understood. Although there general agreement that both maturational and experiential factors affect singing development (e.g., Davidson, McKernon, & Gardner, 1981; Stadler-Elmer, 2006; Welch, 1985), there are few empirical studies of how these factors interact. Welch (1986) proposed a model of singing acquisition in which children's singing behaviors appear in a fixed order from Stage 1, where the words of a song are the initial center of interest rather than the melody, to Stage 5, where there are no significant melodic or pitch errors in a child's vocal productions. Presumably this progression impacted by culture, practical experience, and genetically-driven maturation. Detailed study of singing development requires, first, a definition of singing and, second, a notion of what constitutes mature singing behavior. With respect to the first question, Welch (1994) noted that the judgment of an utterance to be speech or song is defined by a complex web of interacting factors encompassing perception, cognition, physical development, maturation, society, culture, history and intentionality (p. 3). Early in development, singing and talking may be less differentiated than later. Indeed, infant-directed speech often referred to as musical speech because of its exaggerated pitch contours, rhythmic patterning and repetition (Fernald, 1991). The boundaries between speech and song can be even less clear in the vocalizations of infants and young children, and determination muddied by the fact that adults often attempt to over interpret infant vocalizations (Welch, 1994). …

Development of translational methods in spectral analysis of human infant crying and rat pup ultrasonic vocalizations for early neurobehavioral assessment.

The purpose of this article is to describe the development of translational methods by which spectrum analysis of human infant crying and rat pup ultrasonic vocalizations (USVs) can be used to assess potentially adverse effects of various prenatal conditions on early neurobehavioral development. The study of human infant crying has resulted in a rich set of measures that has long been used to assess early neurobehavioral insult due to non-optimal prenatal environments, even among seemingly healthy newborn and young infants. In another domain of study, the analysis of rat put USVs has been conducted via paradigms that allow for better experimental control over correlated prenatal conditions that may confound findings and conclusions regarding the effects of specific prenatal experiences. The development of translational methods by which cry vocalizations of both species can be analyzed may provide the opportunity for findings from the two approaches of inquiry to inform one another through their respective strengths. To this end, we present an enhanced taxonomy of a novel set of common measures of cry vocalizations of both human infants and rat pups based on a conceptual framework that emphasizes infant crying as a graded and dynamic acoustic signal. This set includes latency to vocalization onset, duration and repetition rate of expiratory components, duration of inter-vocalization-intervals and spectral features of the sound, including the frequency and amplitude of the fundamental and dominant frequencies. We also present a new set of classifications of rat pup USV waveforms that include qualitative shifts in fundamental frequency, similar to the presence of qualitative shifts in fundamental frequency that have previously been related to insults to neurobehavioral integrity in human infants. Challenges to the development of translational analyses, including the use of different terminologies, methods of recording, and spectral analyses are discussed, as well as descriptions of automated processes, software solutions, and pitfalls.

Data-driven automated acoustic analysis of human infant vocalizations using neural network tools

Acoustic analysis of infant vocalizations has typically employed traditional acoustic measures drawn from adult speech acoustics, such as f(0), duration, formant frequencies, amplitude, and pitch perturbation. Here an alternative and complementary method is proposed in which data-derived spectrographic features are central. 1-s-long spectrograms of vocalizations produced by six infants recorded longitudinally between ages 3 and 11 months are analyzed using a neural network consisting of a self-organizing map and a single-layer perceptron. The self-organizing map acquires a set of holistic, data-derived spectrographic receptive fields. The single-layer perceptron receives self-organizing map activations as input and is trained to classify utterances into prelinguistic phonatory categories (squeal, vocant, or growl), identify the ages at which they were produced, and identify the individuals who produced them. Classification performance was significantly better than chance for all three classification tasks. Performance is compared to another popular architecture, the fully supervised multilayer perceptron. In addition, the network's weights and patterns of activation are explored from several angles, for example, through traditional acoustic measurements of the network's receptive fields. Results support the use of this and related tools for deriving holistic acoustic features directly from infant vocalization data and for the automatic classification of infant vocalizations.

Longitudinal analysis of vowels in infant-directed speech.

Adult-directed conversational speech (ADS) is characterized by a high level of acoustic imprecision which should theoretically cause problems for infant language learning. Whether infant-directed speech (IDS) is clearer than ADS is disputed. However, differences in prosody [Fernald (1989)], utterance length [Cooper (1997)], and acoustic features [Bernstein Ratner (1984) and Malsheen (1980)] have been found. Such differences have the potential to assist children in decoding language input [Fernald (1985)]. In prior research, the child’s age and language ability appear to affect speech clarification [Bernstein Ratner (1996)]. This study examines whether vowel clarification is a function of the infants’ age. More than 75 mother-infant dyads are being followed from 7 months to 2 years of age. Data reported here are from 10 dyads whose data have been fully analyzed. Plots of the first and second formant values for vowels in words spoken in IDS and ADS were compared at 7 and 11 months of age. Vowels to 7-month-old infants appear to show less clarification than those to 11-month infants, although individual patterns of clarification are evident. This study analyzes whether such variability in vowel clarification affects the rate of early infant vocalizations prior to language production. [Work supported by NSF BCS074512.]

Vocal motoric foundations of spoken language – a commentary on Iverson's ‘Developing language in a developing body: the relationship between motor development and language development’

Vocal motoric foundations of spoken language – a commentary on Iverson's ‘Developing language in a developing body: the relationship between motor development and language development’

How Caregiver's Anticipation Shapes Infant's Vowel Through Mutual Imitation

The mechanism of infant vowel development is a fundamental issue of human cognitive development that includes perceptual and behavioral development. This paper models the mechanism of imitation underlying caregiver-infant interaction by focusing on potential roles of the caregiver's imitation in guiding infant vowel development. Proposed imitation mechanism is constructed with two kinds of the caregiver's possible biases in mind. The first is what we call ?sensorimotor magnets,? in which a caregiver perceives and imitates infant vocalizations as more prototypical ones as mother-tongue vowels. The second is based on what we call ?automirroring bias,? by which the heard vowel is much closer to the expected vowel because of the anticipation being imitated. Computer simulation results of caregiver-infant interaction show the sensorimotor magnets help form small clusters and the automirroring bias shapes these clusters to become clearer vowels in association with the sensorimotor magnets.

Testosterone administration modulates neural responses to crying infants in young females

Parental responsiveness to infant vocalizations is an essential mechanism to ensure parental care, and its importance is reflected in a specific neural substrate, the thalamocingulate circuit, which evolved through mammalian evolution subserving this responsiveness. Recent studies using functional Magnetic Resonance Imaging (fMRI) provide compelling evidence for a comparable mechanism in humans by showing thalamocingulate responses to infant crying. Furthermore, possibly acting on this common neural substrate, steroid hormones such as estradiol and testosterone, seem to mediate parental behavior both in humans and other animals. Estradiol unmistakably increases parental care, while data for testosterone are less unequivocal. In humans and several other animals, testosterone levels decrease both in mothers and fathers during parenthood. However, exogenous testosterone in mice seems to increase parenting, and infant crying leads to heightened testosterone levels in human males. Not only is the way in which testosterone is implicated in parental responsiveness unresolved, but the underlying mechanisms are fully unknown. Accordingly, using fMRI, we measured neural responses of 16 young women who were listening to crying infants in a double blind, placebo-controlled, counterbalanced, testosterone administration experiment. Crucially, heightened activation in the testosterone condition compared to placebo was shown in the thalamocingulate region, insula, and the cerebellum in response to crying. Our results by controlled hormonal manipulation confirm a role of the thalamocingulate circuit in infant cry perception. Furthermore, the data also suggest that exogenous testosterone, by itself or by way of its metabolite estradiol, in our group of young women acted on this thalamocinculate circuit to, provisionally, upregulate parental care.

Audible Television and Decreased Adult Words, Infant Vocalizations, and Conversational Turns

To test the hypothesis that audible television is associated with decreased parent and child interactions. Prospective, population-based observational study. Community. Three hundred twenty-nine 2- to 48-month-old children. Audible television. Children wore a digital recorder on random days for up to 24 months. A software program incorporating automatic speech-identification technology processed the recorded file to analyze the sounds the children were exposed to and the sounds they made. Conditional linear regression was used to determine the association between audible television and the outcomes of interest. Adult word counts, child vocalizations, and child conversational turns. Each hour of audible television was associated with significant reductions in age-adjusted z scores for child vocalizations (linear regression coefficient, -0.26; 95% confidence interval [CI], -0.29 to -0.22), vocalization duration (linear regression coefficient, -0.24; 95% CI, -0.27 to -0.20), and conversational turns (linear regression coefficient, -0.22; 95% CI, -0.25 to -0.19). There were also significant reductions in adult female (linear regression coefficient, -636; 95% CI, -812 to -460) and adult male (linear regression coefficient, -134; 95% CI, -263 to -5) word count. Audible television is associated with decreased exposure to discernible human adult speech and decreased child vocalizations. These results may explain the association between infant television exposure and delayed language development.

The value of vocalizing: five-month-old infants associate their own noncry vocalizations with responses from caregivers.

The early noncry vocalizations of infants are salient social signals. Caregivers spontaneously respond to 30%-50% of these sounds, and their responsiveness to infants' prelinguistic noncry vocalizations facilitates the development of phonology and speech. Have infants learned that their vocalizations influence the behavior of social partners? If they have, infants should show an extinction burst in vocalizing when adults temporarily stop responding to infant vocalizations. Thirty-eight 5-month-olds were tested in the still-face paradigm with an unfamiliar adult. When the adult assumed a still face, infants showed an extinction burst. Thus, 5-month-olds have learned the social efficacy of their vocalizations on caregivers' behavior. Furthermore, the magnitude of 5-month infants' extinction bursts predicted their language comprehension at 13 months.

Adults’ autonomic and subjective emotional responses to infant vocalizations: The role of secure base script knowledge.

This article examines the extent to which secure base script knowledge-as reflected in an adult's ability to generate narratives in which attachment-related threats are recognized, competent help is provided, and the problem is resolved-is associated with adults' autonomic and subjective emotional responses to infant distress and nondistress vocalizations. Adults who demonstrated low levels of secure base knowledge showed greater electrodermal reactivity and stronger declines in their feelings of love while they listened to a recording of an infant crying. In contrast, secure base knowledge was not significantly associated with adults' responses to infant laughter. Results are discussed in terms of their role in extending prior research on the psychophysiology of adult attachment and their possible implications for the intergenerational transmission of attachment-related experience.

Mean Length of Utterance before words and grammar: Longitudinal trends and developmental implications of infant vocalizations

This study measured longitudinal change in six parameters of infant utterances (i.e. number of sounds, CV syllables, supraglottal consonants, and repetitions per utterance, temporal duration, and seconds per sound), investigated previously unexplored characteristics of repetition (i.e. number of vowel and CV syllable repetitions per utterance) and analyzed change in vocalizations in relation to age and developmental milestones using multilevel models. Infants (N=18) were videotaped bimonthly during naturalistic and semi-structured activities between 0 ; 3 and the onset of word use (M=11.8 months). Results showed that infant utterances changed in predictable ways both in relation to age and in relation to language milestones (i.e. reduplicated babble onset, word comprehension and word production). Looking at change in relation to the milestones of language development led to new views of babbling, the transition from babbling to first words, and processes that may underlie these transitions.

Alteration of Adults' Subjective Feeling of Familiarity toward Infants' Sounds

Many adults may have lower subjective feelings of familiarity toward infants' vocalizations since infants' sounds are different from those of adults. However, mothers frequently exposed to infants' vocalizations may be more familiar and less averse. To test this hypothesis, 21 mothers (M age = 31.1 yr., SD = 4.3) of infants (M age = 8.2 mo., SD = 3.5), 18 mothers (M age = 34.4 yr., SD = 4.8) of children between two and five years of age (M age = 2.8 yr., SD = 1.0), and 17 women (M age = 29.2 yr., SD = ll.1) with no children were exposed to 20 types of sounds. Of these sounds, 14 were produced by infants. Although the mothers of infants did not recognize sounds as those of an infant's vocalization, they showed higher subjective feelings of familiarity toward the timbres of the vowel-like stimuli than did the other groups. By contrast, the subjective feelings of familiarity for nonspeech sounds did not differ among groups. Maternal experiences may change women's recognition of perceived sounds.

Vocalizations of deaf infants before and after cochlear implantation

Critical aspects of spoken language depend on perceiving and understanding speech sounds. For deaf infants, however, neither sound perception nor awareness of the sound-making consequences of their actions is available. The goal of this study was to uncover and document early, measurable effects of hearing loss on infant vocalization and changes in these behaviors following cochlear implantation. Participants were 8 deaf infants, 7-11 months old, and 8 infants with cochlear-implants, 12-20 months old and 1-6 months post-implantation. Dependent variables include number of vocalizations, mean vocalization duration, and mean frequency before and after cochlear implantation and in relation to reduplicated babble onset and word production. Post-implant changes in vocal behaviors may have clinical implications for decisions regarding age of implantation and auditory habilitation as well as for understanding post-implant variability.

Babbling Complexity and Its Relationship to Speech and Language Outcomes in Children With Cochlear Implants

To investigate if babbling complexity in early childhood is related to speech and language outcomes in later childhood in children with cochlear implants (CIs). Retrospective. Tertiary care hospital. Nineteen infants with CIs participated. Infants received multichannel CIs. Infant vocal recordings were taken during pre- and post-CI visits up to 13 months post-CI. Vocalizations were measured using a scoring system that takes into account the phonetic complexity of infant vocalizations. Outcome variables included articulation and language measures collected at 4 years of age. Data were analyzed using correlational and regression analyses. : For infants with at least 6 to 9 months of CI experience, the phonetic complexity of babbling is significantly correlated with receptive vocabulary, articulation abilities, and global language skills at 4 years of age. The phonetic complexity of prelinguistic vocalizations is related to later speech and language outcomes in children with CIs. This information may be valuable in terms of tracking progress in pediatric CI users.

Manual actions affect vocalizations of infants

Upper limb gestures, as well as transitive actions (i.e. acted upon an object) when either executed or observed affect speech. Broca's area seems to be involved in integration between the two motor representations of arm and mouth (Bernardis and Gentilucci, Neuropsychologia, 44:178-190, 2006, Gentilucci et al., Eur J Neurosci, 19:190-202, 2004a, Neuropsychologia, 42:1554-1567, 2004b, J Cogn Neurosci, 18:1059-1074, 2006). The relevance of these data is in relation with the hypothesis that language evolved from manual gestures, and was gradually transformed in speech by means of a system of dual motor commands to hand and mouth (Gentilucci and Corballis, Neurosci Biobehav, Rev 30:949-960, 2006). The present study aimed to verify whether this system of integration between gestures (and transitive actions) and speech is involved also in the language development of infants. Vocalizations of infants aged between 11 and 13 months were recorded during both manipulation of objects of different size and request arm gestures towards the same objects presented by the experimenter. Frequency in voice spectra increased when the infants manipulated or gestured to large objects in comparison with the same activities directed to small objects. These data suggest that intrinsic properties of an object evoking commands of manual interaction are used to identify that object, and to communicate.

A method for fundamental frequency estimation and voicing decision: Application to infant utterances recorded in real acoustical environments

This paper proposes a method for fundamental frequency (F0) estimation and voicing decision that can handle wide-ranging speech signals including adult and infant utterances recorded in real noisy environments. In particular, infant utterances have unique characteristics that are different from those of adults, such as a wide F0 range, F0 abrupt transitions, and unique energy distribution patterns over frequencies. Therefore, conventional methods that were developed mainly for adult utterances do not necessarily work well for infant utterances especially when the signals are contaminated by background noise. Several techniques are introduced into the proposed method to cope with this problem. We show that the ripple-enhanced power spectrum based method (REPS) can estimate the F0s robustly, and that the use of instantaneous frequency (IF) enables us to refine the accuracy of the F0 estimates. In addition, the degree of dominance defined based on the IF is introduced as a robust voicing decision measure. The effectiveness of the proposed method is confirmed in terms of gross pitch errors and voicing decision errors in comparison with the recently proposed methods, Praat and YIN, using both longitudinal recordings of Japanese infant utterances and adult utterances.

Vocalizations of Infants with Hearing Loss Compared with Infants with Normal Hearing: Part I – Phonetic Development

Infants with hearing loss are known to be slower to develop spoken vocabulary than peers with normal hearing. Previous research demonstrates that they differ from normal-hearing children in several aspects of prelinguistic vocal development. Less is known about the vocalizations of early-identified infants with access to current hearing technologies. This longitudinal study documents changes in prelinguistic vocalizations in early-identified infants with varying degrees of hearing loss, compared with a group of infants with normal hearing. It was hypothesized that infants with hearing loss would demonstrate phonetic delays and that selected aspects of phonetic learning may be differentially affected by restricted auditory access. The vocalizations and early verbalizations of 21 infants with normal hearing and 12 early-identified infants with hearing loss were compared over a period of 14 mo (from 10 to 24 mo of age). Thirty-minute mother-child interaction sessions were video recorded at 6- to 8-wk intervals in a laboratory playroom setting. Syllable complexity changes and consonantal development were quantified from vocalizations and early verbalizations. Early behaviors were related to speech production measures at 36 mo of age. Participants with hearing loss were recruited from local audiology clinics and early intervention programs. Participants with normal hearing were recruited through day care centers and pediatrician offices. Relative to age-matched, normal-hearing peers, children with hearing loss were delayed in the onset of consistent canonical babble. However, certain children with moderately-severe losses babbled on time, and infants with cochlear implants babbled within 2 to 6 mo of implantation. The infants with hearing loss had smaller consonantal inventories and were slower to increase syllable shape complexity than age-matched normal-hearing peers. The overall pattern of results suggested that consonant development in infants with hearing loss was delayed but not qualitatively different from children with normal hearing. Delays appeared to be less pronounced than suggested by previous research. However, fricative/affricate development progressed slowly in infants with hearing loss and divergence from the patterns of normal-hearing children was observed. Six children (2 with normal hearing; 4 with hearing loss) were identified as atypical, based on their rates of development. At 24 mo of age, these children persisted in producing a high proportion (0.59) of vocalizations lacking consonants, which was negatively correlated with Goldman-Fristoe scores at 36 mo (r = -0.60). Results suggest that early-identified children are delayed in consonant and syllable structure development, which may influence early word learning rates. Fricative/affricate development appears to be challenging for some infants with hearing loss. This may be related to the effects of sensorineural hearing loss on high-frequency information, restricted bandwidth provided by amplification, and reduced audibility in contexts of noise and reverberation. Delayed fricative use may have implications for morphological development. Atypically slow rates of change in syllable development may indicate that a child is at risk for delayed speech development.

Vocalizations of Infants with Hearing Loss Compared with Infants with Normal Hearing: Part II – Transition to Words

By 24 mo of age, most typically developing infants with normal hearing successfully transition to the production of words that can be understood about 50% of the time. This study compares early phonological development in children with and without hearing loss to gain a clearer understanding of the effects of hearing loss in early-identified children. A secondary goal was to identify measures of early phonetic development that are predictors of later speech production outcomes. The vocalizations and early words of 21 infants with normal hearing and 12 early-identified infants with hearing loss were followed longitudinally over a period of 14 mo (from 10 to 24 mo of age). Thirty-minute mother-child interaction samples were video recorded at 6- to 8-wk intervals in a laboratory playroom setting. Vocalizations produced at 16 and 24 mo were categorized according to communicative intent and recognizable words versus other types. Groups were compared on the structural complexity of words produced at 24 mo of age. Parent report measures of vocabulary development were collected from 10 to 30 mo of age, and Goldman-Fristoe Test of Articulation scores at 36 mo were used in regression analyses. Both groups increased the purposeful use of voice between 16 and 24 mo of age. However, at 24 mo of age, the toddlers with hearing loss produced significantly fewer words that could be recognized by their mothers. Their samples were dominated by unintelligible communicative attempts at this age. In contrast, the samples from normal hearing children were dominated by words and phrases. At 24 mo of age, toddlers with normal hearing were more advanced than those with hearing loss on seven measures of the structural complexity of words. The children with normal hearing attempted more complex words and productions were more accurate than those of children with hearing loss. At 10 to 16 mo of age, the groups did not differ significantly on parent-report measures of receptive vocabulary. However, the hearing loss group was much slower to develop expressive vocabulary and demonstrated larger individual differences than the normal hearing group. Six children identified as atypical differed from all other children in vowel accuracy and complexity of word attempts. However, both atypical infants and typical infants with hearing loss were significantly less accurate than normal hearing infants in consonant and word production. Early measures of syllable production predicted unique variance in later speech production and vocabulary outcomes. The transition from babble to words in infants with hearing loss appears to be delayed but parallel to that of infants with normal hearing. These delays appear to exert significant influences on expressive vocabulary development. Parents may appreciate knowing that some children with hearing loss may develop early vocabulary at a slower rate than children with normal hearing. Clinicians should monitor landmarks from babble onset through transitions to words. Indicators of atypical development were delayed and/or limited use of syllables with consonants, vowel errors and limited production of recognizable words.

Male parenting and response to infant stimuli in the common marmoset (Callithrix jacchus)

Callithrix jacchus infants are raised in complex family environments where most members participate in rearing the young. Many studies examining male parental behavior have focused on the carrying of infants with observations made within the family context. However, interference from family members can make it difficult to assess the father's motivation to care for infants. Our goals were to develop a testing paradigm for determining an individual's response to infant stimuli separate from family influences, compare a male's motivation to respond to an infant stimulus outside the family with his paternal behavior within the family, to compare responses to infant stimuli of parentally experienced versus inexperienced males and finally to develop a reproducible and standardized method of testing male responsiveness to infant stimulus that could serve to evaluate hormonal manipulations. Fifteen experienced common marmoset fathers were evaluated using three different measures of parental behavior: (1) instantaneous scan sampling, (2) continuous focal sampling in the family, and (3) continuous focal sampling of males presented with four infant stimuli: familiar and unfamiliar infants, familiar and unfamiliar infant vocalizations. Six parentally inexperienced males (non-fathers) served as controls. Males that carried the most in the family were typically the same males that responded most to the infant vocalization tests. Experienced fathers did not differ in their latency to enter the stimulus cage for any of the four infant stimuli response tests while inexperienced males took significantly longer to enter the stimulus cage. In addition, fathers expressed a greater frequency of infant-directed behavior than did the inexperienced males during the unfamiliar infant and unfamiliar vocalization tests. These studies show that experienced male marmosets are highly motivated to interact with infant stimuli and that there is interindividual variability in response to infant vocalizations. Testing males outside of the family allows for a clear assessment of male's interest in infant stimuli in both parentally experienced fathers and inexperienced males.

Development of cognition, communication, and vocalization in hearing impaired infants fitted with hearing aids

To study the characteristics of development of cognition, communication, and vocalization in congenitally hearing impaired infants with hearing aids. Hearing aids were fitted to 39 congenitally hearing impaired infants: 20 of them were fitted with the hearing aids before the age of 8 months (Group A), and 19 of them after the age of 8 months (Group B). Digital video camera was used to record the action, communication, and vocalization of the children. The time needed to be adaptable to the hearing aids of Group A was (0.5+/-0.2) months, significantly shorter than that of Group B [(2.2+/-0.3) months, P<0.01]. The time needed to establish communication by eyes was (0.6+/-0.2) months in Group A, significantly shorter than that in Group B [(2.3+/-0.5) months, P<0.01]. The time needed to present canonical babbling, communication by pointing behaviors, and meaningful words of Group A were (15.0+/-1.8) months, (12.1+/-2.1) months, and (17.3+/-2.2) months respectively, all stigmatically shorter than those of Group B [(23.2+/-8.0) months, (16.1+/-4.5) months, and (32.6+/-10.9) months respectively, all P<0.05)]. However, the time needed to present pre-canonical babbling of Group A was (4.3+/-0.5) months, not significantly different from that of Group B [(4.8+/-0.6) months, P>0.05]. Using the hearing aids early and validly helps acquire good development of cognizance and speech in hearing impaired infants.