Noisy but Effective: Crying Across the First 3 Months of Life

Noise phenomena in distress cries of term and very preterm infants at term-equivalent age

BACKGROUND AND AIM

To examine whether the noise components in distress cries of term infants differed from very preterm infants whose cries were collected at a comparable "corrected" gestational age.

METHODS

Distress cries were collected from 20 term and 20 preterm infants. The cries were acoustically examined for the occurrence of aperiodic phonatory behavior within and across moments of crying.

RESULTS

The findings indicated no significant differences between term and preterm infants at term age in the occurrence of noise.

CONCLUSIONS

Distress cries of both term and term-equivalent preterm infants appear to contain high instances of phonatory noise. The high arousal associated with distress crying and associated increase in subglottal pressure appeared to influence both term and term-equivalent preterm infants similarly.

Cry features of healthy neonates who passed their newborn hearing screening vs. those who did not

OBJECTIVES

Temporal and fundamental frequency (fo) variations in infant cries provide critical insights into the maturity of vocal control and hearing performances. Earlier research has examined the use of vocalisation properties (in addition to hearing tests) to identify infants at risk of hearing impairment. The aim of this study was to determine whether such an approach could be suitable for neonates.

METHODS

To investigate this, we recruited 74 healthy neonates within their first week of life as our participants, assigning them to either a group that passed the ABR-based NHS (PG, N = 36) or a group that did not, but were diagnosed as normally hearing in follow-up check at 3 months of life, a so-called false-positive group (NPG, N = 36). Spontaneously uttered cries (N = 2330) were recorded and analysed quantitatively. The duration, minimum, maximum and mean fo, as well as two variability measures (fo range, fo sigma), were calculated for each cry utterance, averaged for individual neonates, and compared between the groups.

RESULTS

A multiple analysis of variance (MANOVA) revealed no significant effects. This confirms that cry features reflecting vocal control do not differ between healthy neonates with normal hearing, irrespective of the outcome of their initial NHS.

CONCLUSIONS

Healthy neonates who do not pass the NHS but are normal hearing in the follow-up (false positive cases) have the same cry properties as those with normal hearing who do. This is an essential prerequisite to justify the research strategy of incorporating vocal analysis into NHS to complement ABR measures in identifying hearing-impaired newborns.

Acoustic parameters of voice in typically developing children ages 4-19 years

OBJECTIVES

Report data on acoustic measures of voice in sustained vowels produced by typically developing children, aged 4-19 years, to add to the cross-sectional reference values in a pediatric database.

METHODS

Recordings of sustained vowel/ɑ/phonation were obtained from 158 children (80 males, 78 females) aged 4-19 years who were judged to be typically developing with respect to speech and voice. Acoustic analyses were performed with the Multidimensional Voice Program (MDVP™) and the Analysis of Dysphonia in Speech and Voice (ADSV™), both from Pentax Medical.

RESULTS

Values from both MDVP and ADSV are reported for children in the following age cohorts: 4-6 years, 7-9 years, 10-12 years, 13-15 years, and 16-19 years.

CONCLUSION

The data in this study complement previously published data and contribute to a pediatric reference database useful for research and for clinical practice related to children's voice. Acoustic parameters most sensitive to age and sex are identified.

Melody complexity of infants' cry and non-cry vocalisations increases across the first six months

In early infancy, melody provides the most salient prosodic element for language acquisition and there is huge evidence for infants' precocious aptitudes for musical and speech melody perception. Yet, a lack of knowledge remains with respect to melody patterns of infants' vocalisations. In a search for developmental regularities of cry and non-cry vocalisations and for building blocks of prosody (intonation) over the first 6 months of life, more than 67,500 melodies (fundamental frequency contours) of 277 healthy infants from monolingual German families were quantitatively analysed. Based on objective criteria, vocalisations with well-identifiable melodies were grouped into those exhibiting a simple (single-arc) or complex (multiple-arc) melody pattern. Longitudinal analysis using fractional polynomial multi-level mixed effects logistic regression models were applied to these patterns. A significant age (but not sex) dependent developmental pattern towards more complexity was demonstrated in both vocalisation types over the observation period. The theoretical concept of melody development (MD-Model) contends that melody complexification is an important building block on the path towards language. Recognition of this developmental process will considerably improve not only our understanding of early preparatory processes for language acquisition, but most importantly also allow for the creation of clinically robust risk markers for developmental language disorders.

Associations Between Neonatal Cry Acoustics and Visual Attention During the First Year

It has been suggested that early cry parameters are connected to later cognitive abilities. The present study is the first to investigate whether the acoustic features of infant cry are associated with cognitive development already during the first year, as measured by oculomotor orienting and attention disengagement. Cry sounds for acoustic analyses (fundamental frequency; F0) were recorded in two neonatal cohorts at the age of 0–8 days (Tampere, Finland) or at 6 weeks (Cape Town, South Africa). Eye tracking was used to measure oculomotor orienting to peripheral visual stimuli and attention disengagement from central stimuli at 8 months (Tampere) or at 6 months (Cape Town) of age. Only a marginal positive correlation between fundamental frequency of cry (F0) and visual attention disengagement was observed in the Tampere cohort, but not in the Cape Town cohort. This correlation indicated that infants from the Tampere cohort with a higher neonatal F0 were marginally slower to shift their gaze away from the central stimulus to the peripheral stimulus. No associations between F0 and oculomotor orienting were observed in either cohort. We discuss possible factors influencing the current pattern of results suggesting a lack of replicable associations between neonatal cry and visual attention and suggest directions for future research investigating the potential of early cry analysis in predicting later cognitive development.

Musical Intervals in Infants' Spontaneous Crying over the First 4 Months of Life

INTRODUCTION

Perception and memorizing of melody and rhythm start about the third trimester of gestation. Infants have astonishing musical predispositions, and melody contour is most salient for them.

OBJECTIVE

To longitudinally analyse melody contour of spontaneous crying of healthy infants and to identify melodic intervals. The aim was 3-fold: (1) to answer the question whether spontaneous crying of healthy infants regularly exhibits melodic intervals across the observation period, (2) to investigate whether interval events become more complex with age and (3) to analyse interval size distribution.

METHODS

Weekly cry recordings of 12 healthy infants (6 females) over the first 4 months of life were analysed (6,130 cry utterances) using frequency spectrograms and pitch analyses (PRAAT). A preselection of utterances containing a well-identifiable, noise-free and undisturbed melodic contour was applied to identify and measure melodic intervals in the final subset of 3,114 utterances. Age-dependent frequency of occurrence of melodic intervals was statistically analysed using generalized estimating equations.

RESULTS

85.3% of all preselected melody contours (n = 3,114) either contained single rising or falling melodic intervals or complex events as combinations of both. In total 6,814 melodic intervals were measured. A significant increase in interval occurrence was found characterized by a non-linear age effect (3 developmental phases). Complex events were found to significantly increase linearly with age. In both calculations, no sex effect was found. Interval size distribution showed a maximum of the minor second as the prevailing musical interval in infants' crying over the first 4 months of life.

CONCLUSION

Melodic intervals seem to be a regular phenomenon of spontaneous crying of healthy infants. They are suggested to be a further candidate for developing an early risk marker of vocal control in infants. Subsequent studies are needed to compare healthy infants and infants at risk for respiratory-laryngeal dysfunction to investigate the diagnostic value of the occurrence of melodic intervals and their age-depending complexification.

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.

Acoustic Correlates and Adult Perceptions of Distress in Infant Speech-Like Vocalizations and Cries

Prior research has not evaluated acoustic features contributing to perception of human infant vocal distress or lack thereof on a continuum. The present research evaluates perception of infant vocalizations along a continuum ranging from the most prototypical intensely distressful cry sounds ("wails") to the most prototypical of infant sounds that typically express no distress (non-distress "vocants"). Wails are deemed little if at all related to speech while vocants are taken to be clear precursors to speech. We selected prototypical exemplars of utterances representing the whole continuum from 0 and 1 month-olds. In this initial study of the continuum, our goals are to determine (1) listener agreement on level of vocal distress across the continuum, (2) acoustic parameters predicting ratings of distress, (3) the extent to which individual listeners maintain or change their acoustic criteria for distress judgments across the study, (4) the extent to which different listeners use similar or different acoustic criteria to make judgments, and (5) the role of short-term experience among the listeners in judgments of infant vocalization distress. Results indicated that (1) both inter-rater and intra-rater listener agreement on degree of vocal distress was high, (2) the best predictors of vocal distress were number of vibratory regimes within utterances, utterance duration, spectral ratio (spectral concentration) in vibratory regimes within utterances, and mean pitch, (3) individual listeners significantly modified their acoustic criteria for distress judgments across the 10 trial blocks, (4) different listeners, while showing overall similarities in ratings of the 42 stimuli, also showed significant differences in acoustic criteria used in assigning the ratings of vocal distress, and (5) listeners who were both experienced and inexperienced in infant vocalizations coding showed high agreement in rating level of distress, but differed in the extent to which they relied on the different acoustic cues in making the ratings. The study provides clearer characterization of vocal distress expression in infants based on acoustic parameters and a new perspective on active adult perception of infant vocalizations. The results also highlight the importance of vibratory regime segmentation and analysis in acoustically based research on infant vocalizations and their perception.

Duration and Voice Quality of Early Infant Vocalizations

PURPOSE

Infant vocal durations have been studied from a variety of perspectives, including medical, social, and linguistic. The resultant developmental profile across the first 6 months of life, however, is still far from clear. The purpose of this study was to evaluate the durational properties of infant vocalizations from the unique perspective of voice quality. By considering an infant's modal and nonmodal voice qualities, the developmental range of vocalizations produced by infants during the early months of life was captured.

METHOD

Four Australian English-speaking infants were recorded for approximately 1 hr per week during the first 6 months of life. A total of 6,309 vocalizations were perceptually identified and labeled according to voice quality. The duration of each vocalization was subsequently measured.

RESULTS

A nonlinear curve was evident for the duration of all vocalizations combined. Duration increased significantly between Months 3 and 5. Modal voice was the only voice quality that displayed a linear increase in duration across the study. All other voice qualities displayed polynomial trends.

CONCLUSIONS

Based on the current results, the inconsistent pattern of vocal duration development found previously can be reconciled when voice quality properties of vocalizations are taken into account. A nonlinear curve is evident when a broad corpus of infant vocalizations is used, whereas a narrow corpus containing predominantly modal vocalizations displays a linear trend. The results demonstrate the necessity of including nonmodal voice qualities in infant duration experiments so as to not overstate the linear nature of duration increases.

Fundamental Frequency of Crying in Two-month-old Boys and Girls: Do Sex Hormones During Mini-puberty Mediate Differences?

OBJECTIVE

To evaluate whether the puberty-like sex hormone surge during the first months of life (mini-puberty) affects fundamental frequency (fo) in infant crying as one would derive from hormone influences on voice in adults.

STUDY DESIGN

Populational prospective study.

PARTICIPANTS

Twenty healthy normal-hearing infants (nine boys) were recruited for participation.

METHODS

Spontaneously uttered cries were collected from each infant at 8 weeks of age. The cries were acoustically analyzed for mean fo and fo range. The fo properties were correlated to the average serum levels of bioavailable estradiol (E2) (mean E2/sex hormone-binding globulin [SHBG]) and testosterone (T) (mean T/SHBG) across the second month of life.

RESULTS

Whereas no significant hormone effect was found for mean fo, a significant negative correlation (r = -0.55) was found between fo range and mean E2/SHBG. No indication for a T influence on fo features was found at this age. Although girls showed a slightly higher mean E2 concentration than boys did, the observed differences in cry fo range were judged to be reflective of an infant's serum concentration of E2 rather than a sex-based difference.

CONCLUSION

In the absence of laryngeal size differences between female and male infants, the result was interpreted as indicative of an E2 influence on viscoelastic properties of the vocal folds. In our opinion, the investigation of young infants' vocalizations during the early postnatal surge of sex steroids (mini-puberty) may advance our understanding of the mechanisms mediating average sex differences in vocal development and early communication.