Digital Kymography Research Articles

Characterization of Vocal Fold Vibration in Sulcus Vocalis Using High-Speed Digital Imaging.

The aim of the present study was to qualitatively and quantitatively characterize vocal fold vibrations in sulcus vocalis by high-speed digital imaging (HSDI) and to clarify the correlations between HSDI-derived parameters and traditional vocal parameters. HSDI was performed in 20 vocally healthy subjects (8 men and 12 women) and 41 patients with sulcus vocalis (33 men and 8 women). Then HSDI data were evaluated by assessing the visual-perceptual rating, digital kymography, and glottal area waveform. Patients with sulcus vocalis frequently had spindle-shaped glottal gaps and a decreased mucosal wave. Compared with the control group, the sulcus vocalis group showed higher open quotient as well as a shorter duration of the visible mucosal wave, a smaller speed index, and a smaller glottal area difference index ([maximal glottal area - minimal glottal area]/maximal glottal area). These parameters deteriorated in order of the control group and Type I, II, and III sulcus vocalis. There were no gender-related differences. Strong correlations were noted between the open quotient and the type of sulcus vocalis. HSDI was an effective method for documenting the characteristics of vocal fold vibrations in patients with sulcus vocalis and estimating the severity of dysphonia.

High-speed Imaging of Vocal Fold Vibration Onset Delay: Normal Versus Abnormal

Vocal fold vibration onset delay (VFVOD) is heard frequently in spasmodic dysphonia and in muscle tension dysphonia. VFVOD changes due to other vocal pathologies have not been investigated. VFVOD during sustained vowel production was estimated with high-speed video in 10 normal and 40 pathologic subjects (scars, vocal fold paralysis, vocal fold nodules, and polyps). Analysis of high-speed video was done using digital kymography. VFVOD can be divided into two portions. Pre-phonation delay (PPD) is the duration when the vocal folds are nearly approximated to the time of first observed oscillation. Steady state delay (SSD) is the time when vocal folds are observed to come into oscillation until steady state of oscillation is observed. Normal subjects have almost zero PPD with vocal fold oscillation observed before full vocal fold adduction. Pathologic cases showed prolonged PPD because of (1) false cord adduction, (2) prolonged true vocal fold adduction, and (3) delay to onset of vocal fold vibration. Normal subjects have SSD of three to five cycles before steady state. Pathologic states result in increased SSD. Causes for increased SSD include (1) slow ramping up to steady state, (2) partial vibration of vocal folds, and (3) diplophonia with alternating beats before achieving steady state. There are significant differences between normal and pathology groups in both PPD and SSD. VFVOD is elevated in pathologic states. This can be due to increase in PPD or SSD. VFVOD is an under-recognized phenomenon that may contribute to complaints of vocal fatigue and dysphonia.

Real-time Simultaneous DKG and 2D DKG Using High-speed Digital Camera

For the evaluation of voice disorders, direct observation of vocal cord vibration is important. Among the various methods, laryngeal videostroboscopy (LVS) is widely used, but it was not a true image because it collects images from different cycles. In contrast, high-speed videoendoscopy and videokymography have much higher frame rates and can assess functional and mobility disorders. The purpose of the study is to describe real-time, simultaneous digital kymography (DKG), two-dimensional scanning (2D) DKG, and multi-frame (MF) LVS system using a high-speed digital camera, and identify the efficacy of this system in evaluating vibratory patterns of pathologic voice. The pattern of vocal fold vibration was evaluated in a vocally healthy subject and in subjects with vocal polyp, vocal nodules, vocal cord scar, and vocal cord paralysis. We used both quantitative (left-right phase symmetry, amplitude symmetry index) and qualitative (anterior-posterior phase symmetry) parameters for assessment of vocal fold vibration. Our system could record videos within seconds and required relatively little memory. The speed of replay in the DKG, 2D DKG, MF LVS, and high-speed videoendoscopy was controllable. The number of frame per cycle with MF LVS was almost the same as the fundamental frequency. Our system can provide images of various modalities simultaneously in real time and analyze morphological and functional vibratory patterns. It can be possible to provide a greater level of information for the diagnosis and treatment of vibratory disorders.

Quantifying the Subharmonic Mucosal Wave in Excised Larynges via Digital Kymography

In this paper, a nonlinear least squares fitting method was proposed to quantify subharmonic mucosal waves. Subharmonic mucosal waves from 10 excised canine larynges were recorded using digital kymography and analyzed using nonlinear least squares and linear least squares methods. Amplitudes of fundamental and subharmonic mucosal wave components of right-upper, right-lower, left-upper, and left-lower vocal fold lips were calculated. Lastly, phase differences of fundamental and subharmonic components of the left and right vocal folds were compared. The results showed that the nonlinear least squares analysis method provides a more effective complement to the linear fitting method for subharmonic mucosal wave extraction. There was a significant difference in amplitudes between the subharmonic and the fundamental components of mucosal waves (P < 0.05). The phase differences of the fundamental and the subharmonic components of the right and left vocal folds were not significantly different. The application of the nonlinear least squares analysis method in digital kymography is useful for the characterization of subharmonic mucosal waves.

The First Application of the Two-Dimensional Scanning Videokymography in Excised Canine Larynx Model

Evaluation of the vibratory pattern of vocal folds is of paramount importance to diagnose vocal fold disorders. Currently, laryngeal videokymography (VKG) and digital kymography from high-speed videolaryngoscopy are the available techniques for studying aperiodic vibrations of vocal folds. But VKG has the fundamental limitation that only linear portion of the vocal fold mucosa can be visualized. Digital kymography has the disadvantages of no immediate feedback during examination, considerable waiting time before kymographic visualization, recoding duration limited to seconds, and extreme demands on storage space. We developed a new system--two-dimensional (2D) scanning VKG--for evaluation of the vibratory pattern of vocal folds, and the method provided a possible alternative with its advantages and disadvantages. Thus, we aimed to evaluate the feasibility of the new device for the vocal fold vibration in excised canine larynx model. The vibrating pattern for vocal folds was evaluated using high-speed videolaryngoscopic and 2D scanning videokymographic system in the excised canine larynx model. The images of canine vocal folds were captured with high-speed videolaryngoscopic system and converted to the kymographic images using the software. The kymographic image acquired by 2D scanning VKG was comparable with multi-line digital kymography at multiple locations. The vocal fold vibration could be evaluated in the excised canine larynx model using 2D scanning VKG. And this new device is expected to be a promising tool to evaluate the vocal fold vibration for clinical practice and voice research.

Preliminary Study of the Open Quotient in an Ex Vivo Perfused Human Larynx.

Scientific understanding of human voice production to date is a product of indirect investigations including animal models, cadaveric tissue study, or computational modeling. To our knowledge, direct experimentation of human voice production has previously not been possible owing to its invasive nature. The feasibility of an ex vivo perfused human phonatory model has recently allowed systematic investigation in virtually living human larynges with parametric laryngeal muscle stimulation. To investigate the association between adductor muscle group stimulation and the open quotient (OQ) (the fraction of the cycle during which the glottis remains open) of vocal fold vibration. An ex vivo perfused human tissue study was conducted at a physiology laboratory. Human larynx recovered from organ donors within 2 hours of cardiac death was used. The study was performed on May 19, 2014; data analysis took place from June 1, 2014, to December 15, 2014. Perfusion with donated human blood was reestablished shortly after cardiac death. Ex vivo perfused human phonation was then achieved by providing subglottal airflow under graded neuromuscular electrical stimulation bilaterally to the intrinsic adductor groups and cricothyroid muscles. Phonation resulting from the graded states of neuromuscular stimulation was evaluated using high-speed vibratory imaging; the OQ was derived through digital kymography and glottal area waveform analysis. During constant glottal flow, a stepwise increase in adductor muscle group stimulation decreased the OQ. Quantitatively, OQ values decreased with increased stimulation levels from 2 V (OQ, 1) to 5 V (OQ, 0.68) and reached a lower limit of 8 V (OQ, 0.42). Increased stimulation above maximal muscle deformation was unable to affect OQ beyond this lower limit. To our knowledge, a negative association between adductor muscle group stimulation and phonatory OQ has been demonstrated for the first time in a neuromuscularly activated human larynx. Further experience with the ex vivo perfused human phonatory model will aid in systematically defining this causal relationship.

Imaging and Analysis of Human Vocal Fold Vibration Using Two-Dimensional (2D) Scanning Videokymography

Laryngeal videokymography and high-speed digital kymography are the currently available techniques for studying aperiodic vibration of the vocal folds. However, videokymography has a fundamental limitation that only linear portions of the vocal fold mucosa can be visualized, whereas high-speed digital kymography has the disadvantages of lack of immediate feedback during examination and considerable waiting time before kymographic visualization. We developed a new system, two-dimensional (2D) scanning videokymography, that provides a possible alternative for evaluation of the vibratory pattern of the vocal folds. Herein, we report the application of 2D scanning videokymography for visualization of vocal fold vibration in humans and an analysis of its parameters. Two young healthy volunteers (one man and one woman) took part in this study. The vibratory patterns of their vocal folds were evaluated using 2D scanning videokymography and laryngeal stroboscopy. Two-dimensional scanning videokymography provided a high-definition image of the vibratory movements of the vocal folds. In analysis of the images acquired by the device, various parameters including fundamental frequency; ratio of the vibratory phases; phase, amplitude, and glottal area symmetry; and cycle-to-cycle variability were extracted. Our results indicate that 2D scanning videokymography is a useful and promising tool for visualization of the vibratory movement of the vocal folds. This new technique might improve our understanding of the mechanism of vocal fold vibration and contribute to voice research as well as clinical practice.

Parameters of the assessment of voice quality and clinical manifestation of rheumatoid arthritis

PurposeThe aim of the study was to investigate the voice quality parameters in 72 rheumatoid arthritis (RA) patients and their relationships with the clinical manifestations and disease activity. The control group consisted of 30 healthy subjects. Material and methodsAll RA patients were evaluated by extensive clinical, laboratory and radiographic studies. The phoniatric assessment included the analysis of vocal folds vibrations by digital stroboscopy (DS) of the larynx using HRES ENDOCAM 5562 system, digital kymography (DKG) and High-Speed Digital Imaging (HSDI) technique. The acoustic voice analysis was conducted using DiagnoScope Specialist program. ResultsVoice quality disorders were registered in 32 (44.44%) RA patients and observed more frequently in patients with moderate and severe activity (DAS28≥3.2) than in mild RA. In digital stroboscopy, confirmed by digital kymography, the hypofunctional dysphonia was observed especially in patients with DAS28≥3.2. Outcomes of the subjective assessment of voice quality were in accordance with the objective parameters and acoustic voice examination. ConclusionsIn RA patients the most frequent voice quality disorders with hypofunctional dysphonia were registered. The relationships between voice quality disorders, clinical activity and radiographic progression of RA patients were observed. Digital stroboscopy, digital kymography, High-Speed Digital Imaging and acoustic voice analysis used in the complex diagnosis of RA confirmed the presence of pathological changes in the larynx. There is a need of cooperation between rheumatologists and phoniatricians in the diagnosis and treatment of dysphonia in RA patients.

Vocal Fold Vibratory Changes Following Surgical Intervention

High-speed videoendoscopy (HSV) captures direct cycle-to-cycle visualization of vocal fold movement in real time. This ultrafast recording rate is capable of visualizing the vibratory motion of the vocal folds in severely disordered phonation and provides a direct method for examining vibratory changes after vocal fold surgery. The purpose of this study was to examine the vibratory motion before and after surgical intervention. HSV was captured from two subjects with identifiable midvocal fold benign lesions and six subjects with highly aperiodic vocal fold vibration before and after phonosurgery. Digital kymography (DKG) was used to extract high-speed kymographic vocal fold images sampled at the midmembranous, anterior 1/3, and posterior 1/3 region. Spectral analysis was subsequently applied to the DKG to quantify the cycle-to-cycle movements of the left and the right vocal fold, expressed as a spectrum. Before intervention, the vibratory spectrum consisted of decreased and flat-like spectral peaks with robust power asymmetry. After intervention, increases in spectral power and decreases in power symmetry were noted. Spectral power increases were most remarkable in the midmembranous region of the vocal fold. Surgical modification resulted in improved lateral excursion of the vocal folds, vibratory function, and perceptual measures of Voice Handicap Index-10. These changes in vibratory behavior trended toward normal vocal fold vibration.

Quantification of Vocal Fold Vibration in Various Laryngeal Disorders Using High-Speed Digital Imaging

To quantify vibratory characteristics of various laryngeal disorders seen by high-speed digital imaging (HSDI). HSDI was performed on 78 patients with various laryngeal disorders (20 with polyp, 16 with carcinoma, 13 with leukoplakia, 6 with vocal fold nodule, and 33 with others) and 29 vocally healthy subjects. Obtained data were quantitatively evaluated by frame-by-frame analysis, laryngotopography, digital kymography, and glottal area waveform. Overall, patients with laryngeal pathologies showed greater asymmetry in amplitude, mucosal wave and phase, smaller mucosal wave, and poorer glottal closure than vocally healthy subjects. Furthermore, disease-specific vibratory disturbances that generally agreed with the findings in the literature were quantified: comparing polyp with nodule, differences were noted in longitudinal phase difference, amplitude, and mucosal wave. In comparison with leukoplakia and cancer, nonvibrating area was more frequently noted in cancer. The HSDI analysis of various voice disorders using multiple methods can help phonosurgeons to properly diagnose various laryngeal pathologies and to estimate the degree of their vocal disturbances.

Comparative Analysis of Vocal Fold Vibration Using High-Speed Videoendoscopy and Digital Kymography

To compare high-speed videoendoscopy (HSV) and digital kymography (DKG) in the vocal fold vibration analysis of normophonic women with no vocal fold abnormalities. Prospective study comparing quantitative parameters extracted by HSV and DKG. Eighteen normophonic women whose age ranged from 18 to 45years participated in the study. The procedures comprised HSV and DKG of the medial line of the vocal folds. The parameters evaluated were fundamental frequency (F0), open quotient (OQ), and duration of vibration cycle phases (open phase, closed phase, opening phase, and closing phase). The F0 results of HSV and DKG were similar. However, significant differences were found in both duration of vibration cycle phases and OQ, indicating a longer open phase in the vocal fold vibration when this phase was measured by HSV. The results emphasize the need to set up different normative threshold values for both HSV and DKG.

Spectral Analysis of Digital Kymography in Normal Adult Vocal Fold Vibration

The purpose of this study was to examine the spectrum of normal adult vocal fold vibration obtained through direct visualization technique using digital kymography (DKG). DKG extracts high-speed kymographic images of each vocal fold sampled at a single or multiple points along the vocal folds. Thus, direct and objective quantification of the cycle-to-cycle movements of the left and right vocal folds were obtained. In this study, DKG spectrum configuration in males and females were examined. Samples were obtained from seven subjects (three males and four females) with no history of voice disorders. Subjects were asked to produce tokens obtained from a standard clinical laryngeal evaluation producing tokens at modal, low, and high frequency and at modal frequency with increased loudness. Results demonstrated that the spectrum of normal adult phonation consisted of a large and robust H1 (fundamental frequency) and significant attenuation of power in the higher harmonics (H2, H3). The spectral peaks were quasiperiodic with nospectral smearing. Analysis of the spectral data revealed variations in the spectrum that were influenced by the frequency of phonation and gender. Subjects demonstrated a range of left-right asymmetry of the spectral peaks (2-26%). This study presents a preliminary database of direct spectral characteristics of normal adult vocal fold vibration over a range of frequencies and intensities. Furthermore, these measures provide data from which similar measures obtained from dysphonic pathologies can be compared.

Objective Measures of Laryngeal Imaging: What Have We Learned Since Dr. Paul Moore

Dr. Paul Moore pioneered the use of high-speed cinematography for observation of normal and abnormal vocal fold vibrations during phonation. His analysis of the glottal area waveform, opening and closing speed index, and open quotient from the high-speed films were labor intensive but relevant today. With advances in digital image capture and automated image extraction techniques, stroboscopy and high-speed images of vocal fold vibration may be analyzed with objective measures. Digital high-speed image capture in color is now clinically practical at high resolution. Digital kymography now allows analysis of the vibratory waveform from each vocal fold. Serial capture and comparison can document changes in vibratory function with treatment. Quantification of vocal fold vibration using such techniques is now practical. This is a review of vocal fold vibration capture and analysis techniques since Dr. Moore.

Kymographic imaging of laryngeal vibrations

Kymographic imaging is a modern method for displaying and evaluating vibratory behaviour of the vocal folds which is crucial for voice production. This review summarizes the state of the art of this method, and focuses on the progress in this area within the last 5 years. Videokymography, using a special videocamera, offers high-speed (video)kymographic images in real time, which is advantageous in daily clinical practice. Two other methods use software to create kymograms retrospectively: digital kymography processes high-speed videolaryngoscopic recordings and offers numerous research possibilities, whereas strobovideokymography processes videostroboscopic recordings, and its use is limited to regular vibration patterns. Current studies reveal that high-speed kymographic images allow more reliable visual evaluation of vibrations than by watching video recordings. Image analysis procedures have been advanced to quantify the vibration properties of the vocal folds. New information has been obtained on asymmetry, mucosal waves, irregularities, phonation onset, and nonlinear dynamic phenomena in voice disorders, as well as in singing. High-speed kymography visualizes vibratory features which are not simply observable via traditional methods. It shows large potential in better understanding the functional origin of hoarseness and unsteady phonatory states. Further research in this area is envisioned.

Updates on Endoscopic Laryngeal Imaging

In this paper, I will provide an update on work published in the past 2 years on endoscopic laryngeal imaging techniques including stroboscopy, high-speed digital imaging, and videokymography. There is increasing evidence in the literature from the past 2 years on the clinical usefulness of high-speed digital imaging and kymography as an adjunct to stroboscopy to understand the pathophysiology of hoarseness. The evidence is particularly strong in cases with moderate-to-severe aperiodicity. Recent evidence suggests that these endoscopic imaging techniques (with increased spatial resolution of up to 8,000 frames per second) have potential for objectively characterizing normal and disordered vibratory motion in adults and children. High-speed digital imaging and kymography have the potential to provide quantitative and visual-perceptual measurements of vibratory function that researchers can use to improve the assessment and treatment of voice disorders in children and adults.

Does treatment of the laryngeal mucosa reduce dystonic symptoms? A prospective clinical cohort study of mannose binding lectin and other immunological parameters with diagnostic use of phonatory function studies

This study examined efficacy of the innate immune defence via the mannose binding lectin (MBL) in a cohort of 55 dystonic patients prospectively referred to the clinic with laryngeal mucosal complaints, who were placed on local steroids (budesonid inhaler, 400 μg 2 times daily) and antihistamines (fexofenadin 180 mg mostly 3 times daily) with adjuvant lifestyle corrections. Treatment efficacy of the larynx was assessed based on mucosal findings of the vocal folds examined with phonatory function studies (PhFS) comprising simultaneous high-speed digital images, kymography, electroglottography and voice acoustics combined with a visual score of arytenoids oedema, as these measures are indicative of the magnitude of laryngitis. Lactose and gluten intolerance and immunological analyses of the innate system were made systematically. Results showed that the genetic aspects of immunology did not reveal a role for the innate immune system, represented by the MBL. But an unexpected positive effect of the larynx treatment on dystonia symptoms was found evidenced by reduction of dystonic complaints and more normative results of PhFS, and a reduction of oedema of the inter arytenoids region. Symptoms relieve and better quality of life was observed on follow-up for the dystonia complaints.

Vocal Fold Phase Asymmetries in Patients With Voice Disorders: A Study Across Visualization Techniques

To examine differences in vocal fold vibratory phase asymmetry judged from stroboscopy, high-speed videoendoscopy (HSV), and the HSV-derived playbacks of mucosal wave kymography, digital kymography, and a static medial digital kymography image of persons with hypofunctional and hyperfunctional voice disorders. Differences between the methods of visual judgments and objective measures of left-right phase asymmetry were assessed. The findings were compared with those from a previous study with vocally normal speakers. Forty-nine persons with voice disorders underwent stroboscopy and HSV. The HSV images were processed, resulting in 4 different spatial or kymographic displays. Two types of phase asymmetries, left-right and anterior-posterior, were visually rated. Objective measures of left-right phase asymmetry were obtained. From stroboscopy, the HSV playback, and the HSV-derived playbacks, left-right phase symmetry was judged to be symmetrical in 41%, 32%, and 19% of cases, respectively. This difference in playbacks was not seen for anterior-posterior asymmetry. Correlation between visual judgments and objective measures was mild for stroboscopy and moderate to high for all HSV-based playbacks. The use of kymography appears important for judgments of phase asymmetry. Stroboscopy appears to be sensitive, but possibly not specific, to phase asymmetries. Further development of objective measures is warranted for this feature.

Kymographic characterization of vibration in human vocal folds with nodules and polyps

Digital kymography (DKG) can provide objective quantitative data about vocal fold vibration, which may help distinguish normal from pathological vocal folds as well as nodules from polyps. Case-control study. There were 87 subjects who were separated into three groups: control, nodules, and unilateral polyps, and examined using a high-speed camera attached to an endoscope. Videos were analyzed using a custom MATLAB program, and three DKG line-scan positions (25%, 50%, and 75% of vocal fold length) were used in statistical analyses to compare vocal fold vibrational frequency, amplitude symmetry index (ASI), amplitude order, and vertical and lateral phase difference (VPD and LPD, respectively). Significant differences among groups were found in all vibrational parameters except frequency. Polyps and nodules groups exhibited greater ASI values (less amplitude symmetry) than the control group. Although the control group consistently showed its largest amplitudes at the midline, the polyps group showed larger amplitudes toward the posterior end of the vocal folds. A significant anterior-posterior pattern in amplitude was not found in the nodules group. LPD values were usually largest (most symmetrical) in the control group, followed by nodules and polyps. LPD at the 25% position allowed for differentiation between polyp and nodule groups. The largest VPD (more pronounced mucosal wave) values were usually found in the control group. Vibratory characteristics of normal and pathological vocal folds were quantitatively examined and compared using multiline DKG. These findings may allow for better characterization of pathologies and eventually assist in improving the clinical utility of DKG.

Quantitative Study of Vibrational Symmetry of Injured Vocal Folds Via Digital Kymography in Excised Canine Larynges

Digital kymography and vocal fold curve fitting are blended with detailed symmetry analysis of kymograms to provide a comprehensive characterization of the vibratory properties of injured vocal folds. Vocal fold vibration of 12 excised canine larynges was recorded under uninjured, unilaterally injured, and bilaterally injured conditions. Kymograms were created at 25%, 50%, and 75% of the vocal fold length, and vibratory parameters were compared quantitatively among conditions and were studied with respect to right-left and anterior-posterior symmetries. Anterior-posterior amplitude asymmetry was found in the bilateral condition. The unilateral condition showed significant right-left amplitude asymmetry, and it showed the lowest right-left phase symmetry among the conditions. In condition comparisons, vertical phase difference did not show significant differences among conditions, whereas amplitudes were significantly different among conditions at all line scan positions and most vocal fold lips. Significant differences in frequency were found among the conditions at all 4 vocal fold lips, with the bilateral condition exhibiting the greatest frequency. Digital kymography and curve fitting provide detailed information about the vibratory behavior of injured vocal folds. Awareness of vibratory properties associated with vocal fold injury may aid in diagnosis, and the quantitative abilities of digital kymography may allow for objective treatment selection.

Typing Vocal Fold Vibratory Patterns in Excised Larynx Experiments Via Digital Kymography

Signal typing is central to the understanding of vocal fold vibratory patterns. Digital kymography (DKG) allows the direct observation of vocal fold vibratory patterns, and therefore, using DKG for vibratory signal typing may provide a useful complement to traditional signal typing techniques. Video data collected from 20 larynges excised from mongrel dogs were observed with DKG in order to find examples of type 1 (nearly periodic), type 2 (subharmonic), and type 3 (aperiodic) vibratory patterns. The time series, frequency spectra, and correlation dimensions were calculated for each signal type. The type 1 pattern showed a periodic time series of glottal edges and a discrete frequency spectrum. The type 2 vibratory pattern displayed a time series of alternating high- and low-amplitude waves and a frequency spectrum that included a subharmonic (F0/2) frequency component. Regular and symmetric vibratory patterns were observed in the type 1 and type 2 patterns. The type 3 vibratory pattern was characterized by an aperiodic time series of glottal edges, a broadband frequency spectrum, and irregular and asymmetric vibratory patterns. The correlation dimension estimates increased from type 1 to type 2 to type 3. Imaging with DKG demonstrated an ability to assign a signal type to various laryngeal vibrations. Signal typing techniques utilizing direct observation of the vocal folds could be useful in determining valid methods for the analysis of vocal fold vibrations.