High-speed Videoendoscopy Research Articles

Analysis of vocal fold movement and voice onset behavior in patients with laryngopharyngeal reflux based on high speed laryngeal high-speed videoendoscopy

Objective:Patients with Laryngopharyngeal Reflux（LPR） have chronic inflammation of the laryngeal mucosa leading to a high response state in the larynx, which may make the vocal fold movement too fast. This paper discusses the characteristics of vocal fold movement and voice onset by analyzing laryngeal high-speed videoendoscopy in patients with LPR. Methods:Forty patients with LPR were enrolled as LPR group. The diagnostic criteria of LPR included positive reflux symptom index（RSI） and reflux syndrome score（RFS） to identify suspected LPR, objective oropharyngeal DX pH monitoring was carried out, and positive Ryan index indicated reflux. According to age and sex matching, 40 healthy volunteers were selected as the normal group. Laryngeal high-speed videoendoscopy, and the vocal fold motion and vibration parameters, including vocal fold adduction time, vocal fold abduction time, vocal fold vibration onset mode（vocal onset time and mode） and the opening quotient of vocal fold vibration cycle. Statistical analysis was performed using SPSS 25.0. Results:The time of vocal fold adduction in LPR group（mean 225.81ms） was less than that in normal group（mean 277.01 ms）, and the difference was statistically significant（P<0.05）. There was no significant difference in adduction time between LPR group and normal group（P>0.05）. The vocal onset time in LPR group was significantly longer than that in normal group（P<0.05）. High speed video endoscope showed that there were 17 patients with hard onset in LPR group and 8 patients with hard onset in normal group, the difference was statistically significant（P<0.05）. There was no significant difference in the open quotient of vocal fold vibration between LPR group and normal group（P>0.05）. The vocal fold abduction time in LPR group（mean 372.92 ms） was less than that in normal group（mean 426.98ms）, but the difference was not statistically significant（P>0.05）. The time difference of bilateral abduction of vocal fold in LPR group was significantly higher than that in normal group（P<0.05）. Conclusion:The larynx of LPR patients is in a high response state, the vocal fold moves faster, and it is more likely to have a hard vocal onset. These may result in voice dysfunction.

3D reconstruction of vocal fold dynamics with laser high-speed videoendoscopy in children.

The objective of this study is to evaluate three-dimensional vertical motion of the superior surface of the vocal folds in vivo in (a) typically developing children as a function of vocal frequency variations and (b) a child with vocal nodules. A custom developed laser endoscope coupled with high-speed videoendoscopy was used to obtain 3D parameters from 2 healthy children, one child with vocal nodules, and 23 vocally healthy adults (females = 11, males = 12). Parameters of amplitude (mm), maximum opening/closing velocity (mm/s), and mean opening/closing velocity (mm/s) were computed for the lateral and vertical vibratory motion along the anterior, middle, and posterior sections of the vocal folds were computed. We provide for the first time, absolute measurements of vertical amplitude and maximum/ mean velocity during the opening and closing phases, in vivo in children. Overall, the vertical motion was larger in vocally normal children compared with the lateral motion, especially along the visible posterior section of the vocal folds and during low pitch phonation. The opening phase dynamics were consistently large along the posterior section in the child with vocal nodules. The study findings establish the feasibility of capturing 3D motion in a clinical setting and provide proof of concept for the application of the proposed 3D laser in the pediatric population. Future large sample size studies are needed to establish the diagnostic potential of examining the closing phase vertical motion to evaluate vibratory development in children with normal voice and investigating the opening phase vertical motion in children with nodules. N/A.

Supraglottic Laryngeal Maneuvers in Adductor Laryngeal Dystonia During Connected Speech

ObjectiveAdductor laryngeal dystonia (AdLD) disrupts fine motor movements of vocal folds during speech, resulting in a strained, broken, and strangled voice. Laryngeal high-speed videoendoscopy (HSV) in connected speech enables the direct visualization of detailed laryngeal dynamics, hence, it can be effectively used to study AdLD. The current study utilizes HSV to investigate supraglottic laryngeal tissue maneuvers obstructing the view of the vocal folds, in AdLD and normophonic speakers during connected speech. Characterizing the laryngeal maneuvers in these groups can facilitate a deeper understanding of the normophonic voice physiology and AdLD voice pathophysiology. MethodsHSV data were obtained from six normophonic speakers and six patients with AdLD during production of connected speech. Three experienced raters visually analyzed the data to determine laryngeal tissues leading to obstructions of vocal folds in HSV images. The raters recorded the duration of each obstruction and indicated the specific tissue(s) leading to the obstruction After the completion of their individual visual analysis, the raters came to consensus about their observations and measurements. ResultsStatistical analysis indicated that AdLD patients exhibited higher occurrences of vocal fold obstructions and longer durations of obstructions compared to the normophonic group. Similar obstruction types were found in both groups, with the epiglottis being the primary site of obstruction for both. Participants with AdLD displayed significantly elevated occurrences of sphincteric compression resulting in vocal fold obstruction. ConclusionHSV can be used to study the movements of laryngeal tissues in detail during connected speech. The analysis of supraglottic laryngeal tissue dynamics in speech can help us characterize the AdLD pathophysiology. The study's findings regarding the tissues implicated in obstructions may potentially inform the development of patient-specific therapeutic strategies targeting individual control over specific laryngeal muscles during phonation and speech production.

Preliminary Findings of Vocal Fold Vibratory Characteristics of Singers Analyzed by Laryngeal High-Speed Videoendoscopy

ObjectivesThis study investigates the vocal fold vibratory dynamics of singers, which are postulated to differ from those of normal speakers due to the singers' regular vocal training. The measurement of vocal fold vibration involved the utilization of laryngeal high-speed video endoscopy (LHSV) and subsequent LHSV-based analysis. The focus is to characterize and compare the LHSV-based measures derived from the glottal area waveform (GAW), namely fundamental frequency (F0GAW), glottal perturbation (jitterGAW and shimmerGAW), open quotient (OQGAW), and Nyquist plots, between singers and normal speakers across genders. MethodsParticipants comprised 13 singers from a local cultural and heritage academy and 56 normal speakers from a local university, all were evaluated to have normal voices. Each participant underwent LHSV procedures to capture images of vocal fold vibration, which were subsequently analyzed to generate the LHSV-based measures. ResultsMale singers exhibited lower F0GAW, jitterGAW, shimmerGAW, and OQGAW than female singers. When compared to normal speakers, male singers demonstrated higher F0GAW, and lower jitterGAW and shimmerGAW. No difference in OQGAW was found between male singers and normal speakers. Female singers exhibited lower jitterGAW compared to normal speakers, but no differences were observed in shimmerGAW and OQGAW. The results of Nyquist plots indicated no gender-related associations between types of rim width and among singers. However, for rim pattern, male singers were associated with a higher percentage of clustered rim, suggesting more regular vocal fold vibration, compared to female singers and male normal speakers. ConclusionsSingers, particularly male singers, demonstrate distinct and potentially superior vocal fold vibrations compared to normal speakers, likely attributed to their regular vocal training, resulting in refined vocal fold configurations even during speaking. Despite the limited sample of singers, the study offers valuable insights into the vocal fold vibratory behaviors in singers analyzed using LHSV.

Visualization and Analysis of Vocal Fold Dynamics in Various Voice Disorders

Objectives/HypothesisThis study aims to compare the glottal dynamics of vocal fold leukoplakia, laryngitis, and papilloma using various visualization techniques, including phonovibrograms (PVG) and glottovibrograms (GVG). It hypothesizes that these techniques can provide understanding of the vibratory dynamics of these voice disorders, which can aid in their objective diagnosis and deriving visual features for computer-assisted classifications. Study DesignThis work employs a comparative analyses of vocal fold disorders using visualization techniques. The study examines phonovibrograms (PVG), derivative of PVG (PVG-1), digital kymograms (DKG) and glottovibrograms (GVG) to analyze the glottal dynamics of vocal fold leukoplakia, laryngitis, and papilloma. MethodsThe study utilizes high-speed video (HSV) endoscopy to capture vocal fold behavior in different pathological conditions. PVG, GVG and DKG techniques are applied to visualize and analyze the vibratory patterns of the vocal folds. PVG offers a comprehensive portrayal of vocal fold motion, while GVG presents the distance between vocal fold contours. The study also examines PVG-1 as a derivative of PVG. ResultsDistinct modifications in vocal fold vibrations across various stages (open, closed, closing, and opening) are documented using PVG, PVG-1, GVG, DKG, and PVG trajectory. Healthy vocal folds exhibit consistent periodic patterns, while disorders like leukoplakia, laryngitis, and papilloma manifest unique features due to structural and functional variations. The methods employed identify both structural irregularities and functional deviations in vocal fold vibrations. ConclusionsComparative analyses using PVG and other visualization techniques aids in understanding the glottal dynamics of voice disorders. While laryngoscopy and stroboscopy are valuable for real-time assessment, offline analysis techniques like PVG and GVG are useful for tracking glottal dynamics during phonation and assessing treatment effectiveness over time. Studies like this will contribute to standardizing the PVG based diagnostic criteria for its clinical utility, and development of classification tools for improved diagnosis and management of vocal fold pathologies.

Analyzing Vocal Fold Frequency Dynamics Using High-Speed 3D Laser Video Endoscopy.

To examine changes in lateral and vertical vibratory motion along the anterior, middle, and posterior sections of the vocal folds, as a function of vocal frequency variations. Absolute measurements of vocal fold surface dynamics from high-speed videoendoscopy with custom laser endoscope were made on 23 vocally healthy adults during sustained /i:/ production at 10%, 20%, and 80% of pitch range. The 3D parameters of amplitude (mm), maximum velocity opening/closing (mm/s), and mean velocity opening/closing (mm/s) were computed for the lateral and vertical vibratory motion along the anterior, middle, and posterior sections of the vocal folds. Linear mixed model analysis was conducted to evaluate the differences in (a) vocal frequency levels (high vs. normal vs. low pitch), (b) axis level (vertical vs. lateral), (c) position level (anterior vs. middle vs. posterior), and (d) gender differences (male vs. female). Overall, the superior surface vertical motion of the vocal fold is greater compared with the lateral motion, especially in males. Along the superior surface, the mean and maximum closing velocities are greater posteriorly for low pitch. The location (anterior, middle, and posterior) along the superior surface is relevant only for vocal fold closing rather than opening, as the dynamics are different along the various locations. The study highlights the significance of assessing the vertical motion of the superior surface of the vocal fold to understand the complex dynamics of voice production. NA Laryngoscope, 134:3267-3276, 2024.

Analysis of potential influencing factors for acoustic quality in patients with ectodermal dysplasia

Subjects with ectodermal dysplasia (ED) suffer from an inherited disorder in the development of ectodermal structures. They show a significantly reduced formation of teeth, hair, and a reduced number and activity of sweat and salivary glands. Recently, the voice of ED subjects has come into focus. It is assumed that the generally reduced glandular function is responsible for the altered vocal sound, although no specific cause has been identified. Previous findings included significant changes in the acoustic quality, the parameters derived from high-speed videoendoscopy, the laboratory analysis and rheological analysis of saliva samples as a substitute for laryngeal mucus. Based on these findings, we performed an extended statistical analysis directed towards the correlations between the different affected domains in order to reveal the contributing factors for the resulting acoustic voice quality. Although there were distinct statistical differences between ED males and male controls in the individual domains, only few statistical correlations were found between the subdomains i.e., acoustics, vocal fold vibrations and saliva composition/consistency. These results do not yet allow any definitive conclusions on the influencing factors of voice quality. A larger group of test subjects and analyses of the laryngeal mucus are required.

Neural network-based estimation of biomechanical vocal fold parameters.

Vocal fold (VF) vibrations are the primary source of human phonation. High-speed video (HSV) endoscopy enables the computation of descriptive VF parameters for assessment of physiological properties of laryngeal dynamics, i.e., the vibration of the VFs. However, underlying biomechanical factors responsible for physiological and disordered VF vibrations cannot be accessed. In contrast, physically based numerical VF models reveal insights into the organ's oscillations, which remain inaccessible through endoscopy. To estimate biomechanical properties, previous research has fitted subglottal pressure-driven mass-spring-damper systems, as inverse problem to the HSV-recorded VF trajectories, by global optimization of the numerical model. A neural network trained on the numerical model may be used as a substitute for computationally expensive optimization, yielding a fast evaluating surrogate of the biomechanical inverse problem. This paper proposes a convolutional recurrent neural network (CRNN)-based architecture trained on regression of a physiological-based biomechanical six-mass model (6 MM). To compare with previous research, the underlying biomechanical factor "subglottal pressure" prediction was tested against 288 HSV ex vivo porcine recordings. The contributions of this work are two-fold: first, the presented CRNN with the 6 MM handles multiple trajectories along the VFs, which allows for investigations on local changes in VF characteristics. Second, the network was trained to reproduce further important biomechanical model parameters like VF mass and stiffness on synthetic data. Unlike in a previous work, the network in this study is therefore an entire surrogate of the inverse problem, which allowed for explicit computation of the fitted model using our approach. The presented approach achieves a best-case mean absolute error (MAE) of 133 Pa (13.9%) in subglottal pressure prediction with 76.6% correlation on experimental data and a re-estimated fundamental frequency MAE of 15.9 Hz (9.9%). In-detail training analysis revealed subglottal pressure as the most learnable parameter. With the physiological-based model design and advances in fast parameter prediction, this work is a next step in biomechanical VF model fitting and the estimation of laryngeal kinematics.

Objective evaluation of the pharyngoesophageal segment as a source of substitute phonation in patients after total laryngectomy

The study aimed to identify objective predictors of the successful voice rehabilitation after total laryngectomy to select the optimal method of voice restoration.Material and Methods. The study included 60 laryngectomized male patients who were stratified into 2 equal groups depending on the patient’s choice of voice restoration: tracheoesophageal puncture or esophageal voice. A comprehensive assessment of the qualitative and quantitative parameters of the pharyngoesophageal segment was carried out using the diagnostic procedures, such as: fiberoptic endoscopic evaluation of swallowing, high-speed video endoscopy, and high-resolution pharyngoesophageal manometry. The results of examination of the pharyngoesophageal segment were compared with the results of voice rehabilitation.Results. A significant difference in the resting pressure in the pharyngoesophageal segment between patients with successful and unsuccessful voice rehabilitation was found. The resting pressure in the pharyngoesophageal segment was higher in patients with unsuccessful voice rehabilitation than in patients with successful voice rehabilitation. Among patients with failed voice rehabilitation, 64 % had pseudodiverticula, 25 % had cicatricial strictures and 11 % had pharyngospasm. Pseudodiverticula were found only in patients who underwent vertical or apparatus pharyngeal closure. We described vibrating patterns of substitute phonation in laryngectomized patients and identified 5 different types of pseudoglottis. No significant differences between the methods of substitute phonation were found.Conclusion. The state of pharyngoesophageal segment is an objective predictor of successful substitute phonation and depends on the surgical technique of pharyngeal closure, the volume of cancer treatment and the course of the postoperative period. A comprehensive assessment of the qualitative and quantitative parameters of the pharyngoesophageal segment using fiberendoscopic, fuoroscopic studies and highresolution pharyngoesophageal manometry allows prediction of voice rehabilitation outcomes.

Empirical Distribution of Glottal Edges (EDGE): A Statistical Assessment of Vocal Fold Kinematics Using High-Speed Videoendoscopy.

Although laryngeal high-speed videoendoscopy (HSV) is crucial for studying vocal fold vibrations, its translation to clinical practice has been hindered by the large volume of data it produces and the difficulty in interpreting current analysis methods. Although image processing techniques have been developed to map spatial-temporal data into two-dimensional representations, they alter the geometrical construction of the glottis and do not provide standard quantitative features, thus challenging clinical interpretation. In response, we propose a new visualization and analysis framework for assessing the dynamics of vocal folds based on the empirical distribution of the glottal edge using HSV. This procedure analyzes vocal fold oscillations by preserving the shape of the glottis and quantifying the asymmetry between right and left vocal fold displacements along the anterior-posterior axis. This method was evaluated on four groups of participants: ten with normal voices, ten with vocal fold nodules, ten with muscle tension dysphonia, and two with unilateral vocal fold paralysis. The proposed method produces distinct representations for normal and pathological vocal fold vibratory behaviors and derived features based on amplitude and phase asymmetry metrics that show statistically significant differences between normal and pathological groups. Comparative analysis with state-of-the-art techniques indicates that our proposed method can complement the assessment of vocal fold vibration and enhance the clinical translation of HSV.

Value of high-speed videoendoscopy as an auxiliary tool in differentiation of benign and malignant unilateral vocal lesions

PurposeThe study aimed to assess the relevance of objective vibratory parameters derived from high-speed videolaryngoscopy (HSV) as a supporting tool, to assist clinicians in establishing the initial diagnosis of benign and malignant glottal organic lesions.MethodsThe HSV examinations were conducted in 175 subjects: 50 normophonic, 85 subjects with benign vocal fold lesions, and 40 with early glottic cancer; organic lesions were confirmed by histopathologic examination. The parameters, derived from HSV kymography: amplitude, symmetry, and glottal dynamic characteristics, were compared statistically between the groups with the following ROC analysis.ResultsAmong 14 calculated parameters, 10 differed significantly between the groups. Four of them, the average resultant amplitude of the involved vocal fold (AmpInvolvedAvg), average amplitude asymmetry for the whole glottis and its middle third part (AmplAsymAvg; AmplAsymAvg_2/3), and absolute average phase difference (AbsPhaseDiffAvg), showed significant differences between benign and malignant lesions. Amplitude values were decreasing, while asymmetry and phase difference values were increasing with the risk of malignancy. In ROC analysis, the highest AUC was observed for AmpAsymAvg (0.719; p < 0.0001), and next in order was AmpInvolvedAvg (0.70; p = 0.0002).ConclusionThe golden standard in the diagnosis of organic lesions of glottis remains clinical examination with videolaryngoscopy, confirmed by histopathological examination. Our results showed that measurements of amplitude, asymmetry, and phase of vibrations in malignant vocal fold masses deteriorate significantly in comparison to benign vocal lesions. High-speed videolaryngoscopy could aid their preliminary differentiation noninvasively before histopathological examination; however, further research on larger groups is needed.

Laryngeal, Respiratory, and Acoustic Characteristics of Vocal Trillo With Simultaneous High-Speed Videoendoscopy, Inductive Plethysmography, and Acoustic Recordings

ObjectiveThis study aimeed to examine the characteristics of formed and unformed trillo, an essential ornament found in 17th-century Italian vocal music, using simultaneous multimodality voice measurements. Participant and MethodsA 28-year-old female with 12 years of classical voice training and 7 years of advanced training in historical performance produced formed trillo, unformed trillo, oscillating trill, vibrato, and straight tone on the vowel /i/. Simultaneous high-speed videoendoscopy, inductive plethysmography, and acoustic recordings were conducted to examine the laryngeal motion, respiratory kinematics, and output sound characteristics. ResultsThe study findings reveal that trillo in this single participant is not only produced by the periodic adduction/abduction of the vocal fold but also with underlying differences in oscillatory mechanisms and increased glottal flow (use of percent vital capacity) controlled by increased activation of abdominal muscles and/or decreased activation (inspiratory braking) of the diaphragm relative to tidal breathing when compared with straight tone, vibrato, and oscillating trill. The formed trillo differs from the unformed trillo in the oscillatory mechanisms and glottal airflow utilization. ConclusionsThe physiological mechanism responsible for trillo is more complex than simply adduction and abduction. Future studies with a greater number of participants are needed to evaluate the mechanisms responsible for the formation of and the auditory-perceptual differences between the formed versus unformed trillo.

Deep Learning-Based Analysis of Glottal Attack and Offset Times in Adductor Laryngeal Dystonia.

Diagnosis of adductor laryngeal dystonia (AdLD) is challenging as it mimics voice features of other voice disorders. This could lead to misdiagnosis (or delayed diagnosis) and ineffective treatments of AdLD. This paper develops automated measurements of glottal attack time (GAT) and glottal offset time (GOT) from high-speed videoendoscopy (HSV) in connected speech as objective measures that can potentially facilitate the diagnosis of this disorder in the future. HSV data were recorded from vocally normal adults and patients with AdLD during the reading of the "Rainbow Passage" and six CAPE-V (Consensus Auditory-Perceptual Evaluation of Voice) sentences. A deep learning framework was designed and trained to segment the glottal area and detect the vocal fold edges in the HSV dataset. This automated framework allowed us to automatically measure and quantify the GATs and GOTs for the participants. Accordingly, a comparison was held between the obtained measurements among vocally normal speakers and those with AdLD. The automated framework was successfully developed and able to accurately segment the glottal area/edges. The precise automated measurements of GAT and GOT revealed minor, nonsignificant differences compared to the results of manual analysis-showing a strong correlation between the measures by the automated and manual methods. The results showed significant differences in the GAT values between the vocally normal subjects and AdLD patients, with larger variability in both the GAT and GOT measures in the AdLD group. The developed automated approach for GAT and GOT measurement can be valuable in clinical practice. These quantitative measurements can be used as meaningful biomarkers of the impaired vocal function in AdLD and help its differential diagnosis in the future.

Duration of vocal effects due to water resistance therapy

There are only few data about effects of semi-occluded vocal tract exercises on vocal fold oscillation patterns in vivo. Furthermore, it has not yet been clarified for how long these effects last. Material: 16 subjects (8 non-pathological and 8 with vocal fold mass lesion) were asked to sustain a phonation on the vowel /i/. During phonation, the subjects were simultaneously recorded with transnasal high speed videoendoscopy (HSV, 20.000 fps), electroglottography, and audio signals. After that, these subjects performed a Water Resistance Therapy (WRT) for 10 min (tube 30 cm, 9 mm diameter, 5 cm below surface). Repeated measurements of sustained phonation were performed 0, 10, and 30 min after exercising. The data showed strong inter-individual differences concerning the courses of the different measures after WRT. For non-pathological voices, directly after WRT there was a lowering of the Glottal-Area-Waveform derived Period-Perturbation -Quotient, a lowering of the closing quotient. For pathological voices, however, such a decrease was not observable. Five minutes after the exercise such effect was not observable any more. WRT showed strong inter-individual effects in the courses of the evaluated measures. General tendencies of some measures directly after the intervention showed a brief effect of only a few minutes.

Objective tools in pediatric voice therapy: A path to improved outcomes

This is an invited presentation in the Special Session titled, “Voice therapy: objective measurement science and clinical efficacy.” Pediatric dysphonia (hoarseness) is a common condition with prevalence estimates ranging from 1.4% to 23.9%. Dysphonia can be detrimental to children both psychologically and academically; hence, early identification and restoration of optimal vocal health is critical. Direct visualization of vocal fold vibratory patterns is fundamental for appropriate diagnosis and treatment of vocal fold pathology. Thus, evaluation of vocal fold structure and cycle-to-cycle vibratory motion through techniques of direct visualization of the vocal fold is essential for clinical assessment and measurement of treatment outcomes. This session will discuss the most recent advances in objective voice assessment and measurement of voice therapy outcomes in children. The focus will be on discussing an innovative approach that leverages high-speed videoendoscopy and a cutting-edge custom developed laser projection system for quantitative evaluation of lesion size and comprehensive evaluation of opening and closing phase dynamics of the glottal cycle before and after voice therapy in children with vocal fold nodules.

Vocal Vibration Opening Onset Position Abnormality in Patients With Adductor Spasmodic Dystonia by Using High-Speed Endoscopy

To analyze vocal fold vibration onset in patients with adductor laryngeal dystonia (ADLD) by analyzing vocal vibration opening onset position (VVOOP). Case-control study SETTING: A voice center. Eleven patients with ADLD diagnosed in our voice center were enrolled in the ADLD group. Eleven healthy subjects matched by exact age and gender to the ADLD patients were selected as the control group. All subjects underwent laryngeal high-speed video endoscopy. VVOOP and its change were assessed by two otolaryngologists. The multiline video kymography was used to analyze the openquotient (OQ) and standard deviation of OQ. VVOOP had more than one position in 54.6% (6/11) of the patients with ADLD, which was higher than the control group (P<0.05). VVOOP appeared in the front of the vocal fold in 54.6% (6/11) of patients with ADLD and in the back of the vocal fold in 81.8% (9/11) of patients with ADLD. VVOOP can be abnormal in 90.9% (10/11) of patients with ADLD, and the rate of VVOOP abnormality was higher than that of the control group (P<0.05). Of 11, 6 (54.6%) patients with ADLD had a variable VVOOP; thevariability rate of VVOOP was higher than that in the control group(P<0.05). OQ and OQ standard deviation in the ADLD group were significantly greater than in the control group (P<0.05). In patients with ADLD, vocal fold vibration was irregular, and VVOOP was abnormal and had a variable position and could reflect variability of the vocal vibration. Level 4.

Influence of Perspective Distortion in Laryngoscopy.

An experiment with controllable boundaries was designed to assess the influence of the recording angle and distance on two-dimensional (2D) imaging in laryngoscopy and resulting 2D parameter calculation derived from the glottal area waveform (GAW). Two high-speed camera setups were used to synchronously record an oscillating synthetic vocal fold (VF) model, simulating a high-speed videoendoscopy. One camera recorded at variable lateral recording angles and a reference camera in superior perspective. This was performed at different physiological recording distances and for two oscillation modes (with/without contacting VFs). The GAW was derived from the segmented glottis, and two parameters each for the categories of symmetry, periodicity, and closure were calculated, as well as two derivative measures. The percentage difference between the variable and reference camera value pairs was calculated, and the angle and height dependencies were quantified using linear regression. The visual perception of a laryngoscopy was found to be influenced by the lateral recording angle, which may lead to misinterpretation of VF symmetry among inexperienced observers. The strongest influence of recording angle was observed for symmetry parameters, the strongest being the Amplitude Symmetry Index with up to 2.6%/° (p < .05). A dependence on the recording distance was only found for the Maximum Area Declination Rate. The recording angle in 2D laryngoscopy should be carefully considered during visual inspection of the VF dynamics. Most of the investigated objective parameters were unaffected by the examined perspective distortion. However, especially left-right symmetry measures should only be used under controlled boundary conditions to avoid misdiagnosis and misinterpretation. https://doi.org/10.23641/asha.23961183.

Towards image-based laryngeal videostroboscopy using deep learning-enabled compressed sensing

Laryngeal videostroboscopy is an audio-mediated imaging technique allowing the visualization of vocal fold oscillation behavior: the audio signal is used to determine the fundamental frequency F0, which represents the vocal fold oscillation frequency. Knowing F0 allows to trigger the strobe illumination unit to provide a still image or slow-motion view of the vocal fold oscillation. However, this procedure involves several hardware components, noisy audio signals, and a chain of complex, error-prone algorithms that have to be orchestrated. We hypothesize that endoscopic images suffice to determine F0 with a view towards providing an alternative, image-based approach for estimating F0 during laryngeal videoendoscopy. In this study, we show that we are able to predict the relative glottal opening state to create sample points on the glottal area waveform, an endoscopic image-derived signal capable of deriving F0. As imaging frame rates from ordinary endoscopic cameras do not fulfill the Shannon–Nyquist criterion, we solve this problem with compressed sensing. We developed and evaluated the proposed approach using high-speed videoendoscopy (HSV) to simulate different, realistic low frame rates that are similar to those used in videostroboscopy. We show that we are able to predict F0 with over 95% accuracy using at most 75 sample points of a 600 ms long footage. Using endoscopic images and our algorithm only, we showcase that we can achieve a stroboscopic effect. This shows, that our proposed method in combination with the developed algorithm may be considered in the future to be integrated into clinical videostroboscopy.

Optical Flow Glottovibrogram for the examination of vocal fold pathology.

Laryngeal high-speed video endoscopy is performed to examine the cycles of vocal fold vibrations in detail and to diagnose voice abnormalities. One of the recent image processing techniques for visualizing vocal fold vibration is optical flow-based playbacks, which include optical flow kymograms (OFKG) for local dynamics, optical flow glottovibrogram (OFGVG) and glottal optical flow waveforms (GOFW) for global dynamics. In recent times, various optical flow computing algorithms have been developed. In this paper, we used four well-known optical flow algorithms Horn Schunk, Lucas Kanade, Gunnar Farneback, and TVL1 to construct the optical flow playbacks. The proposed playback reliability is examined by comparing them to traditional representations such as Phonovibrogram (PVG). Since PVG and OFGVG are interconnected, a comparison study was carried out to better comprehend their interaction.Clinical Relevance- Both OFGVG and PVG add to the precision of interpreting pathological conditions by offering complementary information to the conventional spatiotemporal representations.

Convolutional neural network for voice disorders classification using kymograms

The diagnosis of voice disorders typically involves examination of laryngoscopic video frames by trained experts. Videokymography (VKG) is a useful clinical tool to represent the glottal dynamics and vibratory patterns as kymographic images. In this work, a 2D Convolutional Neural Network (2D CNN) was used to classify voice disorders from kymograms. High-speed videoendoscopy (HSV) recordings of the ''Benchmark for Automatic Glottis Segmentation'' (BAGLS) database were used as the corpus for the voice disorders. Kymographic images were generated from this corpus. For each classification problem addressed in this work, 90% of the generated kymograms were used to train the network and the remaining 10% was used for testing its classification performance. Classification accuracies of 94.237% and 94.8% were obtained for the two cases of binary classification (healthy vs disorders, and healthy vs muscle tension dysphonia). Ternary classification (healthy vs functional vs organic disorders) of the dataset yielded an accuracy of 93.1%.