Does Hyaluronic Acid Distribution in the Larynx Relate to the Newbornʼs Capacity for Crying?:

Longitudinal Evaluation of Cepstral Peak Prominence in Children

OBJECTIVES

To evaluate whether the acoustic measure of cepstral peak prominence changes during typical development in children 2-7.

METHODS

Data were retrospectively analyzed from the Arizona Child Acoustic Database Repository in this longitudinal cohort study. The Repository contains longitudinal data recordings from 63 total children between 2 and 7 years of age. Thirty-one children met the inclusion criteria for the current analysis (at least five time points of usable speech data, no history of speech or language difficulties, no significant dysphonia, and were monolingual speakers of American English). Cepstral peak prominence measures were calculated in Praat for each child, at each timepoint. Additional acoustic measures of vocal fundamental frequency, vocal intensity, and stimuli length were also calculated. These measures were chosen as previous work has shown they may impact cepstral peak prominence values.

RESULTS

Linear mixed-effects regression models examined the relationship between cepstral peak prominence and age, after controlling for vocal fundamental frequency, vocal intensity, and stimuli length. Within-participant effects of age were found, indicating a trajectory change in which cepstral peak prominence increases with age in this population. This positive relationship between a cepstral peak prominence and age was nonlinear, with a steeper slope between age and cepstral peak prominence after 5 years of age.

CONCLUSIONS

This is the first study to examine the typical developmental trajectory of cepstral peak prominence children between 2 and 7 years, a critical period of vocal development. Cepstral peak prominence increased with age, suggesting an increase in periodicity of vocal fold vibration that coincides with the significant vocal fold structural changes occurring during this time. Outcomes present important normative information on vocal development, essential for effectively understanding the difference between what vocal changes are part of normative development and what changes indicate a voice disorder.

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.

The Relationships Among Vocal Variability, Vocal-Articulatory Coordination, and Dysphonia in Children

OBJECTIVE

The purpose of this study was to evaluate the relationship between vocal variability and variability of vocal-articulatory coordination in children. Furthermore, this study examined if this relationship was impacted by pediatric dysphonia.

STUDY DESIGN

Retrospective analysis of speech samples in the Arizona Child Acoustic Database.

METHODS

Speech samples from children 2-7 years of age were selected for analysis. Vocal variability was defined as the coefficient of variation (CoV) of fundamental frequency, taken from the center of sustained vowels. Variability of vocal-articulatory coordination was defined as the CoV of voice onset time (VOT) of voiceless stop consonants. Both objective and subjective measures of dysphonia were completed for each participant.

RESULTS

Children had a negative correlation between VOT variability and vocal variability. Further analysis indicated that this relationship was present in children with typical developmental levels of dysphonia but absent for children with moderate to severe dysphonia. Increased dysphonia severity was associated with increased vocal variability.

CONCLUSION

Increased VOT variability was associated with decreased vocal variability in children with dysphonia severities consistent with typical vocal development. However, this relationship was not present in children with moderate to severe dysphonia. This study suggests that future work is needed to examine the relationships between the vocal system and vocal-articulatory coordination in children with and without diagnosed voice disorders.

Voice Onset Time in Children With and Without Vocal Fold Nodules

PURPOSE

Voice onset time (VOT) of voiceless consonants provides information on the coordination of the vocal and articulatory systems. This study examined whether vocal-articulatory coordination is affected by the presence of vocal fold nodules (VFNs) in children.

METHOD

The voices of children with VFNs (6-12 years) and age- and gender-matched vocally healthy controls were examined. VOT was calculated as the time between the voiceless stop consonant burst and the vocal onset of the vowel. Measures of the average VOT and VOT variability, defined as the coefficient of variation, were calculated. The acoustic measure of dysphonia, cepstral peak prominence (CPP), was also calculated. CPP provides information about the overall periodicity of the signal, with more dysphonic voices having lower CPP values.

RESULTS

There were no significant differences in either average VOT or VOT variability between the VFN and control groups. VOT variability and average VOT were both significantly predicted by the interaction between Group and CPP. There was a significant negative correlation between CPP and VOT variability in the VFN group, but no significant relationship was found in the control group.

CONCLUSIONS

Unlike previous studies with adults, there were no group differences in average VOT or VOT variability in this study. However, children with VFNs who were more dysphonic had increased VOT variability, suggestive of a relationship between dysphonia severity and control of vocal onset during speech production.

Pediatric Voice Therapy: How Many Sessions to Discharge?

PURPOSE

Voice therapy is the primary treatment for children presenting with benign morphological vocal fold changes. This study examined the number of voice therapy sessions required to meet treatment goals and identified factors that predicted treatment length for pediatric voice patients.

METHOD

An observational cohort design was employed. Data were extracted from the University of Wisconsin-Madison Voice and Swallow Outcome Database. This study examined 62 children who completed a course of voice therapy with a speech-language pathologist (SLP) addressing dysphonia caused by benign vocal fold lesions. Extracted data included patient demographics, auditory-perceptual assessments, acoustic and aerodynamic voice measures, videostroboscopy ratings, and medical comorbidities. Linear regression was used to identify predictors of number of therapy sessions.

RESULTS

Patients received an average of 7.5 sessions of voice therapy prior to discharge. Baseline auditory-perceptual assessment of dysphonia (p = .032), phonation threshold pressure (PTP, p = .005), Glottal Function Index (GFI) score (p = .006), and glottic closure pattern (p = .023) were significant predictors of number of voice therapy sessions. These measures, as well as hourglass glottic closure, predicted longer intervention duration. The regression model had an overall r ² of .62.

CONCLUSIONS

Pediatric voice therapy addressing benign vocal fold lesions and/or laryngeal edema required an average of 7.54 sessions before voice outcomes were sufficiently improved for discharge. More severe overall SLP ratings of dysphonia, GFI scores, PTP, or hourglass glottic closure pattern significantly predicted increased number of therapy sessions prior to discharge. Future work should determine what other factors affect treatment duration and how the efficiency of pediatric voice therapy can be maximized.

Transcriptome Dynamics in the Developing Larynx, Trachea, and Esophagus

The larynx, trachea, and esophagus share origin and proximity during embryonic development. Clinical and experimental evidence support the existence of neurophysiological, structural, and functional interdependencies before birth. This investigation provides the first comprehensive transcriptional profile of all three organs during embryonic organogenesis, where differential gene expression gradually assembles the identity and complexity of these proximal organs from a shared origin in the anterior foregut. By applying bulk RNA sequencing and gene network analysis of differentially expressed genes (DEGs) within and across developing embryonic mouse larynx, esophagus, and trachea, we identified co-expressed modules of genes enriched for key biological processes. Organ-specific temporal patterns of gene activity corresponding to gene modules within and across shared tissues during embryonic development (E10.5-E18.5) are described, and the laryngeal transcriptome during vocal fold development and maturation from birth to adulthood is characterized in the context of laryngeal organogenesis. The findings of this study provide new insights into interrelated gene sets governing the organogenesis of this tripartite organ system within the aerodigestive tract. They are relevant to multiple families of disorders defined by cardiocraniofacial syndromes.

Bioreactors for Vocal Fold Tissue Engineering

It is estimated that almost one-third of the United States population will be affected by a vocal fold (VF) disorder during their lifespan. Promising therapies to treat VF injury and scarring are mostly centered on VF tissue engineering strategies such as the injection of engineered biomaterials and cell therapy. VF tissue engineering, however, is a challenging field as the biomechanical properties, structure, and composition of the VF tissue change upon exposure to mechanical stimulation. As a result, the development of long-term VF treatment strategies relies on the characterization of engineered tissues under a controlled mechanical environment. In this review, we highlight the importance of bioreactors as a powerful tool for VF tissue engineering with a focus on the current state of the art of bioreactors designed to mimic phonation in vitro. We discuss the influence of the phonatory environment on the development, function, injury, and healing of the VF tissue and its importance for the development of efficient therapeutic strategies. A concise and comprehensive overview of bioreactor designs, principles, operating parameters, and scalability are presented. An in-depth analysis of VF bioreactor data to date reveals that mechanical stimulation significantly influences cell viability and the expression of proinflammatory and profibrotic genes in vitro. Although the precision and accuracy of bioreactors contribute to generating reliable results, diverse gene expression profiles across the literature suggest that future efforts should focus on the standardization of bioreactor parameters to enable direct comparisons between studies. Impact statement We present a comprehensive review of bioreactors for vocal fold (VF) tissue engineering with a focus on the influence of the phonatory environment on the development, function, injury, and healing of the VFs and the importance of mimicking phonation on engineered VF tissues in vitro. Furthermore, we put forward a strong argument for the continued development of bioreactors in this area with an emphasis on the standardization of bioreactor designs, principles, operating parameters, and oscillatory regimes to enable comparisons between studies.

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.

The influence of premature birth on laryngeal development for phonation

INTRODUCTION

Dysphonia is a known consequence of premature birth, and is usually associated with endotracheal intubation in the neonatal period or surgical ligation of persistent patent ductus arteriosus. Recently, cases of dysphonia, in the absence of these causative factors, have been reported.

OBJECTIVES

This review seeks to identify literature pertaining to those aspects of laryngeal development that may potentially be disrupted by premature birth. The purpose of the review is to determine whether there is any possible anatomical or physiological explanation for dysphonia to arose solely from premature birth.

METHODS

This scoping review was conducted in accordance with the guidelines prescribed by Arskey and O'Malley (2005). Fifteen relevant papers were identified. Results were categorized into age-related categories, to identify changes in the developmental trajectory. Based on the results of the literature search, a further category of unphonated larynges was added.

RESULTS

Potential differences in the laryngeal framework (e.g., the development of the cricoid cartilage and the shape of the glottis) and vocal fold histology, depending on gestational age and post-natal phonation were identified. Much literature focused on the macula flavae, however, the layers of the lamina propria were also discussed.

DISCUSSION

It is unclear whether the process of differentiation of the layers of the lamina propria, which commences in the second to third months of life in term-born infants, is disrupted by prematurity. Further, development of the macula flavae continues until at least 28 weeks' gestation. Preterm children may not phonate immediately after birth, which may also affect laryngeal development.

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.

Laryngeal pathology at school age following very preterm birth

INTRODUCTION

Intubation injury resulting in laryngeal pathology is recognised as a possible complication of preterm birth, yet few published studies have examined such pathology and its relation to voice outcomes. This study reports on the results of prospective laryngeal function examinations of a cohort of very preterm children, all of whom presented with significant dysphonia at school age.

MATERIALS AND METHODS

The laryngeal pathology of 20 very preterm children, born between 23 and 29 weeks gestation, was examined under halogen and stroboscopic conditions. Laryngeal structure and function were assessed using a rigid laryngoscope or a flexible nasendoscope. The approach was selected based on the age and/or likely compliance of the child.

RESULTS

Nineteen children were found to have structural laryngeal pathology. Fourteen children presented with a chink to the posterior glottis and all demonstrated at least a mild degree of supraglottic hyperfunction. Other common findings were arytenoid prolapse and vocal fold immobility. More isolated findings included posterior scar band, vocal fold atrophy, arytenoid oedema and growth on the vocal folds. One child who presented with structural laryngeal pathology was never intubated.

DISCUSSION

Supraglottic hyperfunction was common to all participants, regardless of the nature and extent of underlying structural laryngeal pathology. Posterior glottic chink was the most common pattern of incomplete vocal fold closure. These data support the hypothesis that very preterm children adopt supraglottic tightening to compensate for underlying laryngeal pathology. The mechanism underlying laryngeal damage in the child who was not intubated is unclear.

CONCLUSIONS

Voice quality of very preterm children is affected by both laryngeal structure and function. A trial of behavioural voice treatment is recommended to evaluate any therapeutic response in this population.

Measuring vocal function in professional music theater singers: construct validation of the Evaluation of the Ability to Sing Easily (EASE)

OVERVIEW

Working music theater singers (MTS) typically have a heavy vocal load and little is known about their perception of vocal function. The Evaluation of the Ability to Sing Easily (EASE) was used to assess professional MTS' perceptions of current singing voice status and to compare scores across demographic and performance characteristics and to evaluate the construct validity of the EASE and its subscales (VF = Vocal Fatigue, PRI = Pathologic-Risk Indicators).

METHODS

Professional MTS (n = 284) completed an online survey including the EASE and two additional Vocal Concern (VC) items. Scores were compared across age, gender, whether currently working, role, perceived vocal load over the past 24 h and self-reported voice problem.

RESULTS

For the whole cohort, statistically significant differences were found on all subscales according to whether or not singers perceived themselves to have a voice problem (p < 0.001). Currently performing singers were significantly different from those not performing in a show on the EASE Total (p = 0.014) and VF (p = 0.002), but not for PRI and VC. In the currently performing singer group, significant differences were found for gender, role and perceived voice problem on the EASE Total and all subscales (p < 0.01). Significantly higher VF scores were recorded for singers with heavy vocal load (p = 0.01), but there were no differences on the EASE Total (p = 0.57), PRI (p = 0.19) or VC subscales (p = 0.53). Among these performing singers, no significant age differences were found for any EASE subscales.

CONCLUSIONS

These findings provide further validation of the EASE as a useful tool for measuring singers' perceptions of vocal function and suggest that the subscales should be scored separately. Future evaluation of the EASE against objective clinical assessments (e.g., videostroboscopy) is recommended.

Functional morphology of the sound-generating labia in the syrinx of two songbird species

In songbirds, two sound sources inside the syrinx are used to produce the primary sound. Laterally positioned labia are passively set into vibration, thus interrupting a passing air stream. Together with subsyringeal pressure, the size and tension of the labia determine the spectral characteristics of the primary sound. Very little is known about how the histological composition and morphology of the labia affect their function as sound generators. Here we related the size and microstructure of the labia to their acoustic function in two songbird species with different acoustic characteristics, the white-crowned sparrow and zebra finch. Histological serial sections of the syrinx and different staining techniques were used to identify collagen, elastin and hyaluronan as extracellular matrix components. The distribution and orientation of elastic fibers indicated that the labia in white-crowned sparrows are multi-layered structures, whereas they are more uniformly structured in the zebra finch. Collagen and hyaluronan were evenly distributed in both species. A multi-layered composition could give rise to complex viscoelastic properties of each sound source. We also measured labia size. Variability was found along the dorso-ventral axis in both species. Lateral asymmetry was identified in some individuals but not consistently at the species level. Different size between the left and right sound sources could provide a morphological basis for the acoustic specialization of each sound generator, but only in some individuals. The inconsistency of its presence requires the investigation of alternative explanations, e.g. differences in viscoelastic properties of the labia of the left and right syrinx. Furthermore, we identified attachments of syringeal muscles to the labia as well as to bronchial half rings and suggest a mechanism for their biomechanical function.