Vocal Fold Vibratory Patterns Research Articles

Acoustic, aerodynamic, and vibrational effects of ventricular folds adduction in an ex vivo experiment.

The excessive adduction of ventricular folds has been observed in patients with dysphonia and professional singers. Whether these changes in the ventricular folds are the cause or just a result of disease progression remains unclear, and their potential pathological and physiological implications are yet to be determined. This study aimed to examine the impact of different degrees of ventricular adduction on acoustics, aerodynamics, and vocal fold vibration. The excised models of mild and severe ventricular adduction were established. We recorded the vibration pattern of vocal folds and ventricular folds and measured acoustic metrics, including fundamental frequency (F0), Jitter, Shimmer, harmonic-to-noise ratio (HNR), and sound pressure level (SPL). Furthermore, we evaluated the aerodynamics index through phonation threshold pressure (PTP), phonation instability pressure (PIP), mean flow rate (MFR), phonation threshold flow (PTF), and phonation instability flow (PIF). Irregular vibrations of the ventricular fold were observed during ventricular adduction. Notably, mild and severe ventricular adduction conditions showed a significant increase in PTP, Shimmer, and Jitter, whereas MFR, PIF, and HNR decreased compared with the control condition. Ventricular adduction leads to the deterioration of acoustic and aerodynamic parameters. The aperiodic and irregular vibration of the ventricular folds may be responsible for this phenomenon, although further experiments are warranted. Understanding the functioning of ventricular folds can be beneficial in directing the treatment of muscle tension dysphonia and improving voice training techniques.Level of evidence: level 4.

Extrinsic Laryngeal Muscle Activity With Different Diameters and Water Depths in a Semi-Occluded Vocal Tract Exercise.

Surface electromyography (sEMG) has been used to evaluate extrinsic laryngeal muscle activity during swallowing and phonation. In the current study, sEMG amplitudes were measured from the infrahyoid and suprahyoid muscles during phonation through a tube submerged in water. The sEMG amplitude values measured from the extrinsic laryngeal muscles and the electroglottographic contact quotient (CQ) were obtained simultaneously from 62 healthy participants (31 men, 31 women) during phonation through a tube at six different depths (2, 4, 7, 10, 15, and 20 cm) while using two tubes with different diameters (1 and 0.5 cm). With increasing depth, the sEMG amplitude for the suprahyoid muscles increased in men and women. However, sEMG amplitudes for the infrahyoid muscles increased significantly only in men. Tube diameter had a significant effect on the suprahyoid sEMG amplitudes only for men, with higher sEMG amplitudes when phonating with a 1.0-cm tube. CQ values increased with submerged depth for both men and women. Tube diameter affected results such than CQ values were higher for men when using the wider tube and for women with the narrower tube. Vocal fold vibratory patterns changed with the depth of tube submersion in water for both men and women, but the patterns of muscle activation differed between the sexes. This suggests that men and women use different strategies when confronted with increased intraoral pressure during semi-occluded vocal tract exercises. In this study, sEMG provided insight into the mechanism for differences between vocally normal individuals and could help detect compensatory muscle activation during tube phonation in water for people with voice disorders.

A novel hybrid model integrating MFCC and acoustic parameters for voice disorder detection

Voice is an essential component of human communication, serving as a fundamental medium for expressing thoughts, emotions, and ideas. Disruptions in vocal fold vibratory patterns can lead to voice disorders, which can have a profound impact on interpersonal interactions. Early detection of voice disorders is crucial for improving voice health and quality of life. This research proposes a novel methodology called VDDMFS [voice disorder detection using MFCC (Mel-frequency cepstral coefficients), fundamental frequency and spectral centroid] which combines an artificial neural network (ANN) trained on acoustic attributes and a long short-term memory (LSTM) model trained on MFCC attributes. Subsequently, the probabilities generated by both the ANN and LSTM models are stacked and used as input for XGBoost, which detects whether a voice is disordered or not, resulting in more accurate voice disorder detection. This approach achieved promising results, with an accuracy of 95.67%, sensitivity of 95.36%, specificity of 96.49% and f1 score of 96.9%, outperforming existing techniques.

Effects of Cognitive Load on Vocal Fold Vibratory Patterns in Bilingual Speakers of Low and High German

Effects of Cognitive Load on Vocal Fold Vibratory Patterns in Bilingual Speakers of Low and High German

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.

Histologic Examination of Vocal Fold Mucosal Wave and Vibration.

Despite gross anatomic and histologic differences between human and canine vocal folds, similar wave patterns have been described yet not fully characterized. We reconstructed vocal fold (VF) vibration in a canine hemilarynx and performed histologic examination of the same vocal fold. We demonstrate comparable wave patterns while exploring the importance of certain anatomic architectures. An in vivo canine hemilarynx was phonated against a glass prism at low and high muscle activation conditions. Vibration was captured using high-speed video, and trajectories of VF medial surface tattooed landmarks were 3D-reconstructed. The method of empirical eigenfunctions was used to capture the essential dynamics of vibratory movement. Histologic examination of the hemilarynx was performed. Oscillation patterns were highly similar between the in vivo canine and previous reports of ex vivo human models. The two most dominant eigenfunctions comprised over 90% of total variance of movement, representing opening/closing and convergent/divergent movement patterns, respectively. We demonstrate a vertical phase difference during the glottal cycle. The time delay between the inferior and superior VF was greater during opening than closing for both activation conditions. Histological examination of canine VF showed not only a thicker lamina propria layer superiorly but also a distinct pattern of thyroarytenoid muscle fibers and fascicles as described in human studies. Histologic and vibratory examination of the canine vocal fold demonstrated human vocal fold vibratory patterns despite certain microstructural differences. This study suggests that the multilayered lamina propria may not be fundamental to vibratory patterns necessary for human-like voice production. NA (Basic science study) Laryngoscope, 134:264-271, 2024.

A Quantitative Examination of Vocal Fold Vibratory Changes Using Two-Dimensional Scanning Digital Kymography After Angiolytic Laser Stripping for Vocal Fold Leukoplakia

Background and Objectives Vocal fold leukoplakia is characterized as white plaque on the epithelium of the vocal folds and can be treated by angiolytic laser stripping surgery. However, postoperative changes in the vibratory patterns of vocal folds have not been investigated quantitatively. The purpose of this study was to investigate the changes in vocal fold vibration after angiolytic laser surgery in patients with unilateral vocal fold leukoplakia using the twodimensional scanning digital kymography (2D DKG).Subjects and Method Medical records of seven males (age=62.14±12.40 yrs) with unilateral vocal fold leukoplakia who underwent angiolytic laser stripping were reviewed. Before and after the surgery (post-operative day=82.57±28.55 days), a multi-dimensional voice assessment was performed along with a 2D DKG study. For 2D DKG images, the amplitude symmetry index (ASI), phase symmetry index (PSI), and open quotient (OQ) were calculated using the ImageJ program. In addition, pre- versus postoperative data were compared, and the correlation between the changes in 2D DKG parameters and voice outcomes was explored.Results Results indicated that the absolute ASI (<i>p</i>=0.028) and OQ (<i>p</i>=0.028) of the 2D DKG study, grade (<i>p</i>=0.038) and breathy (<i>p</i>=0.034) of the GRBAS scale, σPitch measured by the electroglottography (<i>p</i>=0.043), the physical score of the VHI (<i>p</i>=0.042), and the total score (<i>p</i>=0.043) and the tiredness score (<i>p</i>=0.043) of the VFI decreased after surgery. Decrease in the absolute ASI was correlated with changes in the grade (rho=0.850) and breathy (rho=0.777) scale measures, while decreased OQ were correlated with the changes in the physical score of the VHI (rho=0.901) and tiredness score of the VFI (rho=0.847).Conclusion The improved vocal fold vibratory patterns after angiolytic laser surgery for vocal fold leukoplakia can be evaluated objectively using the 2D DKG study. Angiolytic laser stripping enables the preservation of vocal fold vibration after the surgery and is considered a valuable surgical option for treating vocal fold leukoplakia.

Comparison of one-dimensional and three-dimensional glottal flow models in left-right asymmetric vocal fold conditions.

While the glottal flow is often simplified as one-dimensional (1D) in computational models of phonation to reduce computational costs, the 1D flow model has not been validated in left-right asymmetric vocal fold conditions, as often occur in both normal and pathological voice production. In this study, we performed three-dimensional (3D) and 1D flow simulations coupled to a two-mass model of adult male vocal folds and compared voice production at different degrees of left-right stiffness asymmetry. The flow and acoustic fields in 3D were obtained by solving the compressible Navier-Stokes equations using the volume penalization method with the moving vocal fold wall as an immersed boundary. Despite differences in the predicted flow pressure on vocal fold surface between the 1D and 3D flow models, the results showed reasonable agreement in vocal fold vibration patterns and selected voice outcome measures between the 1D and 3D models for the range of left-right asymmetric conditions investigated. This indicates that vocal fold properties play a larger role than the glottal flow in determining the overall pattern of vocal fold vibration and the produced voice, and the 1D flow simplification is sufficient in modeling phonation, at least for the simplified glottal geometry of this study.

Comparison of one-dimensional and three-dimensional glottal flow models in left-right asymmetric vocal fold conditions

While the glottal flow is often simplified as one-dimensional (1D) in computational models of phonation to reduce computational costs, the 1D flow model has not been validated in left-right asymmetric vocal fold conditions, as often occur in both normal and pathological voice production. It is unclear to what extent the 1D model approximates the effect of three-dimensional (3D) flow phenomena and fluid-structure interaction. In this study, we performed 1D and 3D flow simulations coupled with the two-mass vocal fold model and compared vocal fold vibration patterns at different degrees of left-right stiffness asymmetry. The flow and acoustic fields in 3D were predicted by solving the compressible Navier-Stokes equations using the volume penalization method and considering the moving vocal fold wall as an immersed boundary. The results showed that vocal fold vibration amplitudes and left-right phase differences in the 3D flow were predicted by the 1D flow model under conditions of small left-right asymmetry, while vocal fold vibration amplitudes were underestimated at conditions of large left-right asymmetry. This indicates that 1D flow models may be sufficient in modeling phonation under left-right asymmetric conditions, although the performance can be further improved by more accurately predicting air pressure on vocal fold surface.

Assessment of Changes in Laryngeal Configuration and Voice Parameters Among Different Frequencies of Neuromuscular Electrical Stimulation (NMES) and Cumulative Effects of NMES in a Normophonic Subject: A Pilot Study

Neuromuscular electrical stimulation (NMES) is a complementary resource to voice therapy that can be used for the treatment of hypofunctional voice disorders. Although positive clinical studies have been reported, neutral and even potentially harmful effects of NMES are also described in the literature. Furthermore, in the studies examined by the authors, the use of different methods of NMES have been identified, which further contributes to the inconsistent results found among studies. Moreover, limited rationale is provided for the chosen NMES parameters such as electrode placement, frequency of NMES and length of treatment. The aims of this pilot study were to investigate the a) impact of different frequencies of NMES on glottal configuration and vocal fold vibration patterns and b) changes in laryngeal configuration and vocal output across 12 minutes of NMES. Three experiments were carried out looking at changes in laryngeal configuration and voice output using different imaging techniques (fibreoptic nasolaryngoscopy and high-speed video), acoustical analysis (F0, formant analysis, SPL, CPPS and LHSR values), electroglottography (EGG) and Relative Fundamental Frequency (RFF) analyses. Glottal parameters and acoustical measures were recorded before, during, and after stimulation. Data was collected at rest and during phonation. Overall the results showed global changes in laryngeal configuration from normal to hyperfunctional (ie, increased RFF, SPL, CQ, and stiffness). Changes were more pronounced for lower frequencies of NMES and were significant within less than three minutes of application. NMES is an effective resource for the activation of intrinsic laryngeal muscles producing significant levels of adduction within few minutes of application. Lower NMES frequencies produced greater muscle activation when compared to higher frequencies.

Evaluation of Voice and Vocal Fold Vibration after Thyroidectomy Using Two-Dimensional Scanning Digital Kymography and High-Speed Videolaryngoscopy

Vocal dysfunction is one of the major factors that affect the health-related quality of life of patients after thyroidectomy. Conventionally, voice changes after thyroidectomy have been evaluated by videostroboscopy and acoustic analysis. Recently, two-dimensional scanning digital kymography (2D DKG) and high-speed videolaryngoscopy (HSV) have been developed and have shown usefulness in accurately evaluating vocal fold vibration. This study aimed to evaluate changes of vocal fold vibration and voice after thyroidectomy using 2D DKG and HSV. We evaluated the voice and vocal fold movement of 24 female patients who underwent thyroidectomy in a single tertiary hospital from December 2018 to October 2019. We obtained serial 2D DKG and HSV data one day before thyroidectomy, and 1 week and 1 month after surgery. We analyzed the peak glottal area of HSV, amplitude symmetry index, phase symmetry index, and open quotient using the 2D DKG data. The parameters were calculated at three levels of the vocal fold (line 1=anterior, line 2=middle, line 3=posterior). In the same period, we performed a voice analysis evaluating voice frequency, jitter, shimmer, and noise to harmonic ratio. We also assessed maximum phonation time and subjective voice changes with voice handicap index-10 questionnaires. Highest frequency (F-high), frequency range (F-range), and fundamental frequency (F0) decreased at 1 week and 1 month after thyroidectomy compared with preoperative values (P=0.003, 0.004, <0.001 and P=0.002, 0.015, 0.001 at 1 week and 1 month, respectively). The open quotient of 2D DKG in lines 1 and 2 increased at 1 week after thyroidectomy (P=0.011, 0.006) and recovered to preoperative levels at 1 month postoperatively (P=0.189, 0.153). Other quantitative measures by 2D DKG and HSV did not show significant changes between the preoperative and postoperative periods. In a correlation analysis between vocal parameters from the acoustic analysis and the values obtained from 2D DKG and HSV, significant negative correlations were observed between peak glottal area and three factors (F-high, F-range, and F0) at 1 month after surgery (r=-0.589, -0.529, -0.708; P=0.002, 0.008, <0.001, respectively). There were positive correlations between phase symmetry indexes in lines 1 and 2 and shimmer at 1 week after thyroidectomy (r=0.489, 0.425; P=0.015, 0.038, respectively). Phase symmetry index in line 3 showed a significant negative correlation with maximum phonation time at both 1 week and 1 month after surgery (r=-0.497, -0.439; P=0.013, 0.032, respectively). However, there was no correlation between total score on the voice handicap index-10 questionnaires and quantitative measurements of vocal fold vibration. 2D DKG and HSV may provide important information on vocal fold vibratory patterns after thyroidectomy, and measurements made with them were correlated with maximal phonation time and acoustic parameters such as F-high, F-range, F0, shimmer.

Two step convolutional neural network for automatic glottis localization and segmentation in stroboscopic videos.

Precise analysis of the vocal fold vibratory pattern in a stroboscopic video plays a key role in the evaluation of voice disorders. Automatic glottis segmentation is one of the preliminary steps in such analysis. In this work, it is divided into two subproblems namely, glottis localization and glottis segmentation. A two step convolutional neural network (CNN) approach is proposed for the automatic glottis segmentation. Data augmentation is carried out using two techniques : 1) Blind rotation (WB), 2) Rotation with respect to glottis orientation (WO). The dataset used in this study contains stroboscopic videos of 18 subjects with Sulcus vocalis, in which the glottis region is annotated by three speech language pathologists (SLPs). The proposed two step CNN approach achieves an average localization accuracy of 90.08% and a mean dice score of 0.65.

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

To provide data on the measurable vocal fold vibratory differences in children with and without vocal fold lesions using high-speed videoendoscopy. Prospective study, 24 participants (8 healthy; 16 with lesions) between the ages of 5 and 10. 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. 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. 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.

Fully automatic segmentation of glottis and vocal folds in endoscopic laryngeal high-speed videos using a deep Convolutional LSTM Network.

The objective investigation of the dynamic properties of vocal fold vibrations demands the recording and further quantitative analysis of laryngeal high-speed video (HSV). Quantification of the vocal fold vibration patterns requires as a first step the segmentation of the glottal area within each video frame from which the vibrating edges of the vocal folds are usually derived. Consequently, the outcome of any further vibration analysis depends on the quality of this initial segmentation process. In this work we propose for the first time a procedure to fully automatically segment not only the time-varying glottal area but also the vocal fold tissue directly from laryngeal high-speed video (HSV) using a deep Convolutional Neural Network (CNN) approach. Eighteen different Convolutional Neural Network (CNN) network configurations were trained and evaluated on totally 13,000 high-speed video (HSV) frames obtained from 56 healthy and 74 pathologic subjects. The segmentation quality of the best performing Convolutional Neural Network (CNN) model, which uses Long Short-Term Memory (LSTM) cells to take also the temporal context into account, was intensely investigated on 15 test video sequences comprising 100 consecutive images each. As performance measures the Dice Coefficient (DC) as well as the precisions of four anatomical landmark positions were used. Over all test data a mean Dice Coefficient (DC) of 0.85 was obtained for the glottis and 0.91 and 0.90 for the right and left vocal fold (VF) respectively. The grand average precision of the identified landmarks amounts 2.2 pixels and is in the same range as comparable manual expert segmentations which can be regarded as Gold Standard. The method proposed here requires no user interaction and overcomes the limitations of current semiautomatic or computational expensive approaches. Thus, it allows also for the analysis of long high-speed video (HSV)-sequences and holds the promise to facilitate the objective analysis of vocal fold vibrations in clinical routine. The here used dataset including the ground truth will be provided freely for all scientific groups to allow a quantitative benchmarking of segmentation approaches in future.

The effects of age and pitch level on electroglottographic measures during sustained phonation.

The aim of the present study was to use electroglottography (EGG) to explore the effects of age and pitch level on sustained vowel phonation. Thirty female individuals (10 young, 10 middle-aged, and 10 older speakers) without voice disorders or training in singing participated in this study. Eight EGG parameters were measured during sustained vowel production with a high, mid, or low pitch: fundamental frequency, contact quotient, contacting-time quotient, decontacting-time quotient, speed quotient with a midslope criterion (SQ-mid), jitter, shimmer, and the harmonics-to-noise ratio. Age was found to be a significant factor in fundamental frequency, contact quotient, contacting-time quotient, decontacting-time quotient, and SQ-mid. With increasing age, the mean fundamental frequency decreased while the contact quotient increased. The middle-aged and older speakers had more asymmetrical vocal fold vibratory patterns than the young speakers. As for pitch level, the high pitch had a significantly less decontacting-time quotient and greater SQ-mid than low and mid pitches. The lack of significant interaction between age and pitch level indicates that the effects of age and pitch level could be additive. Finally, the discriminant analyses show that contact quotient is an important factor in predicting the age of a voice.

Effects of Different Lung Volume Conditions on Closed Quotient, Vocal Fundamental Frequency and Relative Intensity in Vocally Untrained Female Speakers

The objective of this study was to determine the relationship between lung volume (LV) conditions and vocal fold vibratory patterns using measurements of closed quotient (CQ), fundamental frequency (F0) and relative vocal intensity. Forty-three healthy and vocally untrained females were asked to produce the vowel /a/ following breathing instructions that cued for higher, habitual, or lower LV conditions. Closed quotient was measured by electroglottography (EGG) and analyzed using criterion-level method of 25%. An average of CQ, F0 and relative vocal intensity were obtained. No significant difference was observed in CQ between cued LV conditions; however, there was a trend for CQ to increase in the cued high LV condition. Relative vocal intensity and F0 differed significantly across all conditions with higher F0 and relative vocal intensity observed at the high LV condition. These findings suggested that the use of different cued LVs did not have a significant impact on CQ. This may have been due to (1) the phonatory task, (2) variability in responses to the breathing instructions between individuals, and (3) the measurement of CQ. However, F0 and relative vocal intensity were significantly influenced by the LV. This offers a possible alternative approach in cueing pitch and loudness in singing and voice therapy.

Acoustic Analysis of Voice in School Teachers

The term 'voice' is the acoustic energy generated from the vocal tract that are characterized by their dependence on vocal fold vibratory pattern. Teachers as professional voice users are afflicted with dysphonia and are discouraged with their jobs and seek alternative employment. Loud speaking and voice straining may lead to vocal fatigue and vocal fold tissue damage. The objective of the study is to assess the quality of voice of school teachers before and after teaching practice. Sixty teachers from various schools, volunteered to participate in this study. Acoustic analysis Doctor Speech Tiger Electronics, USA was used to assess the voice quality of the school teachers before and after teaching practice. The data were collected and analyzed using Doctor Speech Tiger Electronics, USA. Analysis was performed in terms of perturbation (jitter and shimmer), fundamental frequency, harmonic to noise ratio and maximum phonation time. We found statistically significant difference in all the four parameters except the Jitter value. The fundamental frequency and shimmer value has significantly increased (P<0.001) and (P=0.002) respectively after teaching practice. Unlikely, there was significant decrease in harmonic to noise ratio value (P<0.001) and maximum phonation time value (P<0.01) after teaching practice. Vocal abuse, overuse, or misuse in teaching practice over a long period of time can result in inadequate phonatory pattern due to vocal fold tissue damage, which ultimately results in vocal nodules or polyps. So voice evaluation is particularly important for professional voice users and for the people who are concerned about their quality of voice.

Periodicity, spectral and electroglottographic analyses of pressed voice in expressive speech

Pressed voice is a type of voice quality produced by pressing/straining the vocal folds, which often appears in Japanese conversational speech when expressing paralinguistic information related to emotional or attitudinal behaviors of the speaker. With the aim of clarifying the acoustic and physiological features involved in pressed voice production, we conducted periodicity, spectral and electroglottographic (EGG) analyses on pressed voice segments extracted from spontaneous dialogue speech of several speakers. Periodicity analysis first indicated that pressed voice is usually accompanied by creaky or harsh voices, having irregularities in periodicity, but can also be accompanied by periodic voices with fundamental frequencies in the range of modal phonation. Spectral analysis indicated power is usually reduced in low frequency components of pressed segments. A spectral measure H1'-A1' was then proposed for characterizing pressed voice segments which commonly has few or no harmonicity. H1'-A1' was shown to be effective for identifying most pressed segments, but fails when nasalization occurs. Vocal fold vibratory pattern analysis from the EGG signals revealed that most pressed voice segments (including nasalized vowels) are characterized by glottal pulses with closed intervals longer than open intervals on average, regardless of periodicity.

Estimation of Source-Filter Interaction Regions Based on Electroglottography

Source-filter interaction is a phenomenon in which acoustic airway pressures influence the glottal airflow at the source (level 1) and the vibration pattern of the vocal folds (level 2). This interaction is most significant when dominant source harmonics are near airway resonances. The influence of acoustic airway pressures on vocal fold vibration (level 2) was studied systematically by changing the supraglottal vocal tract length in human subjects with tube extensions. The subjects were asked to perform fundamental frequency (fo) glides while phonating through tubes of various lengths. An algorithm was developed using the quasi-open quotient extracted from the electroglottograph. Regions of sudden vocal fold vibration pattern change due to source-filter interaction were inferred from contact area changes. The algorithm correctly identified 89% of male and 84.8% of female quantal changes in contact pattern associated with interactions between source harmonics and formants during ascending glides. During the descending glides, the algorithm correctly identified 84% of male and 81.1% of female quantal changes in contact pattern. These results are in comparison with those obtained from the fo-based algorithm (Maxfield etal).

Reliability of High-speed Videoendoscopic Ratings of Essential Voice Tremor and Adductor Spasmodic Dysphonia

The main objectives of this study were to (1) examine intrarater and inter-rater reliabilities in perceptual ratings of vocal fold vibratory patterns and supraglottic characteristics for essential vocal tremor and adductor spasmodic dysphonia (AdSD) using high-speed videoendoscopy (HSV), and (2) to investigate the specificity of the parameters in differentiating these two voice disorders. HSV recordings of 34 cases diagnosed with essential vocal tremor, AdSD, or AdSD with vocal tremor were evaluated blindly by two voice speech pathologists. The two raters examined all HSV video segments twice across nine supraglottic and vocal fold vibratory characteristics for inter-rater and intrarater reliabilities. A separate consensus rating was then developed, with the results analyzed to explore differentiation. Raters demonstrated moderate intrarater reliability with mean Spearman's rho correlation coefficients of 0.68 (rater 1) and 0.73 (rater 2). Moderate inter-rater reliability for the two raters was seen across all parameters with a mean Cohen's kappa coefficient of 0.51. Raters showed higher intrarater and inter-rater reliabilities for supraglottic parameters. Only the presence of tremor differentiated between the two voice disorders in cases with a consistent diagnosis. The high level of concomitance between vocal tremor and AdSD may affect subjective perceptual analysis of supraglottic and vocal fold vibratory patterns. Results indicate similar global involvement of supraglottic laryngeal structures for both vocal tremor and AdSD.