Kinematic measurements of the vocal-fold displacement waveform in typical children and adult populations: quantification of high-speed endoscopic videos

Digital Videokymography: Analysis of Glottal Closure in Adults

INTRODUCTION

High-speed videolaryngoscopy and quantitative analysis of laryngeal images are relevant in accurately diagnosing vocal fold closure patterns.

OBJECTIVE

To analyze the parameters of digital videokymography obtained through high-speed videolaryngoscopy in women and men with complete and incomplete glottal closure, and posterior glottal chink.

METHODS

We conducted an observational, analytical, cross-sectional study with data from 65 adults, which we divided into groups according to sex and glottal closure. Digital videokymography parameters were analyzed using an image-processing program. The Anderson-Darling and Mann-Whitney U tests were used to verify sample normality and compare videokymography parameters between groups, respectively. The significance level was set at 5%.

RESULTS

Among 65 laryngeal images, 20 each were from women with complete and incomplete glottal closure, and 20 and 5 were from men with complete and incomplete glottal closure, respectively. Considering the clinical relevance of the evaluated data, groups of 11 women and 4 men with posterior glottal chink were compared with sex-similar groups with complete glottal closure. Digital videokymography showed a lower maximum and mean vocal fold opening in women with incomplete glottal closure, and a lower dominant left vocal fold-opening amplitude and higher dominant frequency of bilateral vocal fold opening in men with incomplete glottal closure. It also showed a lower closed phase percentage in the posterior region for women and men, with higher closed phase percentage in the anterior and middle regions in women. Both groups with posterior glottal chink showed similar results.

CONCLUSION

Incomplete glottal closure may interfere with the results of the digital videokymography parameters, with higher impact on the posterior vocal fold region in males and the middle and anterior vocal fold regions in females.

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.

Update on the pediatric adverse vocal behavior voice disorders: a clinical practice review

The main causes of voice disorders in children with adverse vocal behavior include benign lesions of the vocal folds caused by voice abuse or misuses, such as vocal fold nodules, vocal fold polyps, and laryngitis. Long-term voice disorders can affect the physical and mental health of children. Reviewing the literature of the last two decades on "Vocal Fold Nodules," "Vocal Fold Polyp," "Voice disorder," "Voice Abuse," "Voice Misuse," "Pediatrics," and "Children" with the appropriate Boolean operators.  Conclusion: A total of 315 results were returned on an initial PubMed search. All articles from 2000 to 2022 written in English or Chinese were screened. Duplicate articles, those relating to adults only or concerned with the malignant lesion of the vocal cord, were excluded, resulting in 196 articles of interest. Relevant references and books have also been consulted, and we provide a review of the pathogenesis, diagnosis, and treatment of these maladaptive vocal behavioral voice disorders. What is Known: • Hoarseness is the most common voice symptom in children, and there are various causes of hoarseness in children. However, there is a lack of reviews on voice disorders caused by adverse vocal habits in children. • Voice training is a conservative treatment method for children with voice disorders , and it is important to clarify the factors that influence the effectiveness of voice training for children. What is New: • This review of the personality and family characteristics of children with adverse vocal behavioural voice disorders provides a valuable guide to the clinical planning of subsequent treatment. • This article discusses and summarises some of the factors that may influence the effectiveness of voice training in children and collates some of the scales and questionnaires currently used in children that are important in predicting the effectiveness of voice training.

Comparative Analysis of Two Methods of Perceptual Voice Assessment

OBJECTIVES

The primary aim was to compare two methods for perceptual evaluation of voice - paired comparison (PC) and visual analog scale (VAS) ratings. Secondary aims were to assess the correspondence between two dimensions of voice- overall severity of voice quality and resonant voice, and to investigate the influence of rater experience on perceptual rating scores and rating confidence scores.

STUDY DESIGN

Experimental design.

METHODS

Voice samples from six children (pre and post therapy) were rated by 15 Speech-Language Pathologists specialized in voice. Raters completed four tasks corresponding to the two rating methods and voice qualities: PC-severity, PC-resonance, VAS-severity, and VAS-resonance. For PC tasks, raters chose the better of two voice samples (better voice quality or better resonance, depending on the task) and indicated the degree of confidence in each choice. Rating and confidence score were combined to produce a number on a 1-10 scale (PC-confidence adjusted). VAS ratings involved rating voices on a scale for degree of severity and resonance, respectively.

RESULTS

PC-confidence adjusted and VAS ratings were moderately correlated for overall severity and also vocal resonance. VAS ratings were normally distributed and had greater rater consistency than PC-confidence adjusted ratings. VAS scores reliably predicted binary PC choices (choice of voice sample only). Overall severity and vocal resonance were weakly correlated and rater experience was not linearly related to rating scores or confidence.

CONCLUSIONS

Results suggest that the VAS rating method holds advantages over PC, including normally distributed ratings, superior consistency of ratings, and the ability to provide more finely grained detail regarding the auditory perception of voice. Overall severity and vocal resonance were not redundant in the current data set, suggesting that resonant voice and overall severity are not isomorphic. Finally, the number of years of clinical experience was not linearly related to perceptual ratings or rating confidence.

Non-Linear Image Distortions in Flexible Fiberoptic Endoscopes and their Effects on Calibrated Horizontal Measurements Using High-Speed Videoendoscopy

Laryngeal images obtained via high-speed videoendoscopy are an invaluable source of information for the advancement of voice science because they can capture the true cycle-to-cycle vibratory characteristics of the vocal folds in addition to the transient behaviors of the phonatory mechanism, such as onset, offset, and breaks. This information is obtained through relating the spatial and temporal features from acquired images using objective measurements or subjective assessments. While these images are calibrated temporally, a great challenge is the lack of spatial calibration. Recently, a laser-projection system allowing for spatial calibration was developed. However, various sources of optical distortions deviate the images from reflecting the reality. The main purpose of this study was to evaluate the effect of the fiberoptic flexible endoscope distortions on the calibration of images acquired by the laser-projection system. Specifically, it is shown that two sources of nonlinear distortions could deviate captured images from reality. The first distortion stems from the wide-angle lens used in flexible endoscopes. It is shown that endoscopic images have a significantly higher spatial resolution in the center of the field of view than in its periphery. The difference between the two could lead to as high as 26.4% error in calibrated horizontal measurements. The second distortion stems from variation in the imaging angle. It is shown that the disparity between spatial resolution in the center and periphery of endoscopic images increases as the imaging angle deviates from the perpendicular position. Furthermore, it is shown that when the imaging angle varies, the symmetry of the distortion is also affected significantly. The combined distortions could lead to calibrated horizontal measurement errors as high as 65.7%. The implications of the findings on objective measurements and subjective visual assessments are discussed. These findings can contribute to the refinement of the methods for clinical assessment of voice disorders. Considering that the studied phenomena are due to optical principles, the findings of this study, especially those related to the effects of the imaging angle, can provide further insights regarding other endoscopic instruments (eg, distal-chip and rigid endoscopes) and procedures (eg, gastroendoscopy and colonoscopy).

Quantitative Analysis of Vocal Fold Vibration using High-Speed Videoendoscopy in Children with and without Bilateral Lesions

OBJECTIVE

To provide data on the measurable vocal fold vibratory differences in children with and without vocal fold lesions using high-speed videoendoscopy.

DESIGN

Prospective study, 24 participants (8 healthy; 16 with lesions) between the ages of 5 and 10.

METHODS

Rigid high-speed videoendoscopy at the rate of 8,000 frames per second was used to examine participants. Four objective vocal fold phase linearity measures were obtained to establish anterior-posterior contact and separation vibratory patterns.

RESULTS

All objective measures showed a difference between nonlesion and bilateral vocal fold lesion groups. Contact-separation patterns in all nonlesion girls and young pre-pubertal boys exhibited an anterior-to-posterior contact and posterior-to-anterior separation; while older boys differed. The objective measures of open quotient, left-right relative phase asymmetry and speed index, showed linear anterior-posterior patterns within the nonlesion group; while the bilateral vocal fold lesion group displayed nonlinear patterns. Patterns in the posterior region of the vocal fold were similar in both groups; while patterns in the anterior region differed.

CONCLUSIONS

This study suggests lesions have an effect on the anterior aspect of vocal fold vibratory patterns specifically anterior to the lesions. Age-related differences for males are also evidenced, prompting further investigation of laryngeal development in males and females from childhood to adulthood. This study could serve as a basis for the development of objective clinical measurements of vocal fold vibration in presence of lesions. Further findings could help redefine the theoretical framework of pediatric voice.

Contribution of laryngeal size to differences between male and female voice production

In this study we investigated the effect of sex- and age-related differences in vocal fold length, thickness, and depth on voice production in a three-dimensional vocal fold model. The results showed that the cause-effect relationships between vocal fold physiology and voice production previously identified in an adult male-like vocal fold geometry remained qualitatively the same in vocal folds with geometry representative of adult females and children. We further showed that the often-observed differences in voice production between adult males, adult females, and children can be explained by differences in length and thickness. The lower F0, higher flow rate, larger vocal fold vibration amplitude, and higher sound pressure level (SPL) in adult males as compared to adult females and children can be explained by differences in vocal fold length. In contrast, the thickness effect dominated and contributed to the larger closed quotient of vocal fold vibration, larger normalized maximum flow declination rate, and lower H1-H2 in adult males as compared to adult females and children. The effect of differences in vocal fold depth was generally small. When targeting a specific SPL, adult males experienced a lower peak vocal fold contact pressure during phonation than adult females and children.

Quantitative and Qualitative Electroglottographic Wave Shape Differences in Children and Adults Using Voice Map-Based Analysis

Purpose The purpose of this study is to identify the extent to which various measurements of contacting parameters differ between children and adults during habitual range and overlap vocal frequency/intensity, using voice map-based assessment of noninvasive electroglottography (EGG). Method EGG voice maps were analyzed from 26 adults (22-45 years) and 22 children (4-8 years) during connected speech and vowel /a/ over the habitual range and the overlap vocal frequency/intensity from the voice range profile task on the vowel /a/. Mean and standard deviations of contact quotient by integration, normalized contacting speed, quotient of speed by integration, and cycle-rate sample entropy were obtained. Group differences were evaluated using the linear mixed model analysis for the habitual range connected speech and the vowel, whereas analysis of covariance was conducted for the overlap vocal frequency/intensity from the voice range profile task. Presence of a "knee" on the EGG wave shape was determined by visual inspection of the presence of convexity along the decontacting slope of the EGG pulse and the presence of the second derivative zero-crossing. Results The contact quotient by integration, normalized contacting speed, quotient of speed by integration, and cycle-rate sample entropy were significantly different in children compared to (a) adult males for habitual range and (b) adult males and adult females for the overlap vocal frequency/intensity. None of the children had a "knee" on the decontacting slope of the EGG slope. Conclusion EGG parameters of contact quotient by integration, normalized contacting speed, quotient of speed by integration, cycle-rate sample entropy, and absence of a "knee" on the decontacting slope characterize the wave shape differences between children and adults, whereas the normalized contacting speed, quotient of speed by integration, cycle-rate sample entropy, and presence of a "knee" on the downward pulse slope characterize the wave shape differences between adult males and adult females. Supplemental Material https://doi.org/10.23641/asha.15057345.

Behavioral Treatment for Benign Vocal Fold Lesions in Children: A Systematic Review

Purpose This systematic review aims to identify, classify, and evaluate existing information regarding treatment for benign vocal fold lesions in children and to identify gaps and limitations that may limit effective pediatric voice treatment. Method A literature search was performed using electronic databases (PubMed and Google Scholar) as well as reference lists from previous reviews, studies, and books. Included in the present review are studies that described behavioral treatment for children with benign vocal fold lesions presumed to be phonotraumatic (vocal fold nodules and edema). Results Twenty-one studies were eligible for inclusion in the review. Eight different research designs were used, and three intervention types were identified: direct voice intervention (voice training), indirect treatment (vocal hygiene or counseling), and comparative studies that contrasted different treatment methods. The most commonly used treatment method was eclectic direct intervention, which focused on vocal exercises or voicing patterns. Postintervention improvement was reported in all studies. In general, findings suggested an advantage of direct over indirect intervention and of longer treatment duration over short-term approaches. Conclusions The findings suggest that behavioral voice therapy may be generally effective in treating children with vocal fold nodules. Several limitations emerged in the corpus of studies reviewed including heterogeneity of research methods, missing information about outcome measures, and inappropriate statistical analyses. Thus, a need exists for further well-designed controlled studies to enhance the body of knowledge about developmental factors affecting vocal treatment outcomes, in particular, vocal fold structure as well as cognitive and linguistic development.

Glottal Airflow and Glottal Area Waveform Characteristics of Flow Phonation in Untrained Vocally Healthy Adults

OBJECTIVE

To examine flow phonation characteristics with regard to vocal fold vibration and voice source properties in vocally healthy adults using multimodality voice measurements across various phonation types (breathy, neutral, flow, and pressed) and loudness conditions (typical, loud, and soft).

PARTICIPANTS AND METHODS

Vocal fold vibration, airflow, acoustic, and subglottal pressure was analyzed in 13 untrained voices (six female and seven male). Participants repeated the syllable / pæ:/ using breathy, neutral, flow, and pressed phonation during typical, loud, and soft loudness conditions. Glottal area (GA) waveforms were extracted from high-speed videoendoscopy; glottal flow was derived from inverse filtering the airflow or the audio signal; and subglottal pressure was measured as the intraoral pressure during /p/ occlusion.

RESULTS

Changes in phonation type and loudness conditions resulted in systematic variations across the relative peak closing velocity derived from the GA waveform for both males and females. Amplitude quotient derived from the flow glottogram varied across phonation types for males.

CONCLUSION

Multimodality evaluation using the GA waveform and the inverse filtered waveforms revealed a complex pattern that varied as a function of phonation types and loudness conditions across males and females. Emerging findings from this study suggests that future large-scale studies should focus on spatial and temporal features of closing speed and closing duration for differentiating flow phonation from other phonation types in untrained adults with and without voice disorders.

Endoscopic Findings in Male Prepubertal Choir Singers

OBJECTIVES/HYPOTHESIS

The male singing voice through puberty undergoes many changes that present challenges for the singer and choral director. The purpose of this study was to discuss the endoscopic findings seen in prepubescent choir singers.

STUDY DESIGN

Single-institution prospective study.

METHODS

Subjects were recruited from the Cincinnati Boychoir and were described as Cooksey stage unchanged or mid-voice I, as described by the Boychoir artistic director. Vocal history was obtained via questionnaire at the initial visit. Subjects with known laryngeal pathologies were excluded. Endoscopic laryngeal examinations were performed using videoendoscopy. During examination, each subject sang four discrete frequencies. Findings of the endoscopic exam were judged by a board-certified pediatric otolaryngologist specializing in pediatric voice.

RESULTS

We evaluated 28 subjects prior to vocal maturation. Their age range was 8 to 13 years old (mean = 10.2 ± 1.2 years). The singing voice category of all 28 subjects was described as soprano vocal range by the Boychoir artistic director. The subjects had a mean of 1.7 ± 1.1 years in the Boychoir (0-5 years). None reported history of vocal issues or voice problems in the past; seven (25%) subjects had vocal fold lesions seen at one or more frequencies; 24 (85%) subjects had a posterior gap seen at one or more frequencies. Two subjects (7%) had a posterior gap at one frequency, C3 and G3, respectively. Five subjects (18%) had a posterior gap at two frequencies, seven subjects (25%) at three frequencies, and 10 subjects (36%) in all four frequencies.

CONCLUSIONS

Our study aimed to describe the laryngeal examination of dedicated Boychoir singers prior to undergoing pubertal development and vocal maturation. In elite pediatric singers we found that vocal nodules are common (25%) and are not correlated with vocal symptoms. These findings may suggest that asymptomatic lesions may be more prevalent than previously thought. In these individuals, posterior glottic gap is common and can be considered a normal glottal configuration.

LEVEL OF EVIDENCE

4 Laryngoscope, 131:592-597, 2021.

Relative Fundamental Frequency in Children With and Without Vocal Fold Nodules

Purpose Relative fundamental frequency (RFF) is an acoustic measure that is sensitive to functional voice differences in adults. The aim of the current study was to evaluate RFF in children, as there are known structural and functional differences between the pediatric and adult vocal mechanisms. Method RFF was analyzed in 28 children with vocal fold nodules (CwVN, M = 9.0 years) and 28 children with typical voices (CwTV, M = 8.9 years). RFF is the instantaneous fundamental frequency (f ₀) of the 10 vocalic cycles during devoicing (vocal offset) and 10 vocalic cycles during the revoicing (vocal onset) of the vowels that surround a voiceless consonant. Each cycle's f ₀ was normalized to a steady-state portion of the vowel. RFF values for the cycles closest to the voiceless consonant, that is, Offset Cycle 10 and Onset Cycle 1, were examined. Results Average RFF values for Offset Cycle 10 and Onset Cycle 1 did not differ between CwVN and CwTV; however, within-subject variability of Offset Cycle 10 was decreased in CwVN. Across both groups, male children had lower Offset Cycle 10 RFF values as compared to female children. Additionally, Onset Cycle 1 values were decreased in younger children as compared to those of older children. Conclusions Unlike previous work with adults, CwVN did not have significantly different RFF values than CwTV. Younger children had lower RFF values for Onset Cycle 1 than older children, suggesting that vocal onset f ₀ may provide information on the maturity of the laryngeal motor system.

Vocal tract shape and acoustic adjustments of children during phonation into narrow flow-resistant tubes

The goal of the study is to quantify the salient vocal tract acoustic, subglottal acoustic, and vocal tract physiological characteristics during phonation into a narrow flow-resistant tube with 2.53 mm inner diameter and 124 mm length in typically developing vocally healthy children using simultaneous microphone, accelerometer, and 3D/4D ultrasound recordings. Acoustic measurements included fundamental frequency (f_o), first formant frequency (F₁), second formant frequency (F₂), first subglottal resonance (F_Sg1), and peak-to-peak amplitude ratio (P_vt:P_sg). Physiological measurements included posterior tongue height (D1), tongue dorsum height (D2), tongue tip height (D3), tongue length (D4), oral cavity width (D5), hyoid elevation (D6), pharynx width (D7). All measurements were made on eight boys and ten girls (6-9 years) during sustained /o:/ production at typical pitch and loudness, with and without flow-resistant tube. Phonation with the flow-resistant tube resulted in a significant decrease in F₁, F₂, and P_vt:P_sg and a significant increase in D2, D3, and F_Sg1. A statistically significant gender effect was observed for D1, with D1 higher in boys. These findings agree well with reported findings from adults, suggesting common acoustic and articulatory mechanisms for narrow flow-resistant tube phonation. Theoretical implications of the findings are discussed.

Relationship Between Acoustic Voice Onset and Offset and Selected Instances of Oscillatory Onset and Offset in Young Healthy Men and Women

OBJECTIVE

This study aimed to investigate the relationship between (1) onset of the acoustic signal (X_1a) and prephonatory phases associated with oscillatory onset and (2) offset of the acoustic signal (X_2a) with the postphonatory events associated with oscillatory offset across vocally healthy adults.

SUBJECTS AND METHODS

High-speed videoendoscopy was captured simultaneously with the acoustic signal during repeated production of /hi.hi.hi/ at typical pitch and loudness from 56 vocally healthy adults (aged 20-42 years; 21 men, 35 women). The relationships between the acoustic sound pressure signal and oscillatory onset and offset events from the glottal area waveforms (GAWs) were statistically investigated using a multivariate linear regression analysis.

RESULTS

The X_1a is a significant predictor of the onset of first oscillatory motion (X_1g) and onset of sustained oscillations (X_2g). X_1a as well as gender are significant predictors of the first medial contact of the vocal folds (X_1.5g). The X_2a is a significant predictor of the first instance of oscillatory offset (X_3g), first instance of incomplete glottal closure (X_3.5g), and complete cessation of (vocal fold) oscillatory motion (X_4g).

CONCLUSIONS

The acoustic signal onset is closely related to the X_1.5g, but the latency between these events is longer for women compared to men. The X_2a occurs immediately after incomplete glottal adduction. The emerging normative group latencies between the onset and offset of the acoustic and the GAW from this study appear promising for future investigations.

Vibratory onset and offset times in children: A laryngeal imaging study

OBJECTIVES

The aim of the study was to evaluate the differences in vibratory onset and offset times across age (adult males, adult females, and children) and waveform types (total glottal area waveform, left glottal area waveform, and right glottal area waveform) using high-speed videoendoscopy.

METHODS

In this prospective study, vibratory onset and offset times were evaluated in a total of 86 participants. Forty-three children (23 girls, 18 boys) between 5 and 11 years and 43 gender matched vocally normal young adults (23 females and 18 males) in the age range (21-45 years) were recruited. Vibratory onset and offset times were calculated in milliseconds from the total, left, and right Glottal Area Waveform (GAW). A two-factor analysis of variance was used to compare the means among the subject groups (children, adult male, and adult female) and waveform type (total GAW, left GAW, right GAW) for onset and offset variables. Post hoc analyses were performed using the Fishers Least Significant Different test with Bonferroni correction for multiple comparisons.

RESULTS

Children exhibited significantly shorter vibratory onset and offset times compared to adult males and females. Differences in vibratory onset and offset times were not statistically significant between adult males and females. Across all waveform types (i.e. total GAW, left GAW, and right GAW), no statistical significance was observed among the subject groups.

CONCLUSION

This is the first study reporting vibratory onset and offset times in the pediatric population. The study findings lay the foundation for the development of a large age- and gender-based database of the pediatric population to aid the study of the effects of maturation of vocal fold vibration in adulthood. The findings from this study may also provide the basis for evaluating the impact of numerous lesions on tissue pliability, and thereby has potential utility for the clinical differentiation of various lesions.

Effects of Vocal Fold Nodules on Glottal Cycle Measurements Derived from High-Speed Videoendoscopy in Children

The goal of this study is to quantify the effects of vocal fold nodules on vibratory motion in children using high-speed videoendoscopy. Differences in vibratory motion were evaluated in 20 children with vocal fold nodules (5–11 years) and 20 age and gender matched typically developing children (5–11 years) during sustained phonation at typical pitch and loudness. Normalized kinematic features of vocal fold displacements from the mid-membranous vocal fold point were extracted from the steady-state high-speed video. A total of 12 kinematic features representing spatial and temporal characteristics of vibratory motion were calculated. Average values and standard deviations (cycle-to-cycle variability) of the following kinematic features were computed: normalized peak displacement, normalized average opening velocity, normalized average closing velocity, normalized peak closing velocity, speed quotient, and open quotient. Group differences between children with and without vocal fold nodules were statistically investigated. While a moderate effect size was observed for the spatial feature of speed quotient, and the temporal feature of normalized average closing velocity in children with nodules compared to vocally normal children, none of the features were statistically significant between the groups after Bonferroni correction. The kinematic analysis of the mid-membranous vocal fold displacement revealed that children with nodules primarily differ from typically developing children in closing phase kinematics of the glottal cycle, whereas the opening phase kinematics are similar. Higher speed quotients and similar opening phase velocities suggest greater relative forces are acting on vocal fold in the closing phase. These findings suggest that future large-scale studies should focus on spatial and temporal features related to the closing phase of the glottal cycle for differentiating the kinematics of children with and without vocal fold nodules.