Open Quotient Research Articles

Impact of phonatory frequency and intensity on glottal area waveform measurements derived from high-speed videoendoscopy

Measurements of glottal area waveform from high-speed videoendoscopy were made on vocally healthy females (n = 41) and males (n = 25) during sustained /i/ production at typical pitch and loudness, high pitch, and soft phonation. Three trials of each condition were performed yielding 594 samples. Statistical analysis of glottal cycle quotients (open quotient (OQ), speed quotient (SQ), rate quotient (RQ), glottal gap index (GGI)), glottal cycle periodicity (amplitude, time (TP)), glottal cycle symmetry (phase asymmetry index, spatial symmetry index, and amplitude symmetry index), glottal area derivative (maximum area declination rate (MADR)), and mechanical stress measures (stiffness index (SI), amplitude-to-length ratio (ALR)) revealed that only SI varied systematically across pitch and loudness conditions for males and females. Variations in pitch and loudness results in changes in SI, ALR, RQ, MADR, and SQ for females, whereas variations in target pitch and loudness results in changes in SI, ALR, RQ, MADR, GGI, OQ, and TP for male speakers. Carefully selecting the laryngeal parameters derived from high-speed videoendoscopy has the potential to provide insights clinically into the known laryngeal biomechanics expected for the increase in pitch and reduction in vocal loudness.

Objective measurement of mucosal wave parameters in diagnosing benign lesions of the vocal folds

Introduction: The diagnostic procedure of phonation is dominated by subjective assessment tools. It seems reasonable to seek methods of quantitative glottal cycle assessment.Objective: The aim of our study was the analysis of open quotients (OQ) of the glottis.Methods: One hundred and twenty-four people were included in the study. Methodology was based on tools available in everyday phoniatrics practice – laryngovideostroboscopy (LVS) and electroglottography (EGG). There were statistically significant differences between control and studied group. Vocal fold polyps, nodules and edema influence glottal function in a different manner, what can be illustrated by objective glottal function parameters. Establishing Videostroboscopic Open Quotient values from three parts of glottis and Electroglottographic Quasi Open Quotient (QOQ) value, can help in dividing patients with benign lesions of vocal folds according to the type of disease.Results and conclusions: Measurement of the open quotient from three parts of the glottis helps to differentially diagnose and localize glottal vocal fold lesions. Videostroboscopic Open Quotient and Electroglottographic QOQ values can be used to quantify the glottal cycle. Videostroboscopic Open Quotient, Electroglottographic QOQ and their ratio varies depending on the type of organic dysphonia.

TWO VIDEOSTROBOKYMOGRAPHIC SOFTWARE PACKAGES FOR EVALUATING OPEN QUOTIENT OF THE VOCAL FOLDS: USER REPORT

Introduction Laryngovideostroboscopy (LVS) is the gold standard in diagnosis of the larynx, but the interpretation of the tool is highly dependent on the examiner’s competence and knowledge. An objective measure of LVS, so far used only subjectively, provides a tool for precise diagnosis of laryngeal diseases. Aim The aim of the study was to test two different types of videostrobokymographic (VSK) software – Divas and DiagnoScope. We also compared measures of Open Quotient obtained using the two programs. Material and Methods 23 LVS recordings from a group of euphonic people were analyzed with Divas software (Xion Medical) and DiagnoScope Specialist software (DiagNova Technologies). Results The mean age in the study group was 41.1 years (women: 39.6; men: 42.4). The mean OQVSK value averaged from all three parts of the glottis measured by Divas was 0.519 and by DiagnoScope, 0.517. A Student t-test showed no significant differences between the parameters. For all measurements, absolute differences were less than 0.18. In 50% of patients, the differences in measurements did not exceed 0.05 and in 87%, 0.1. The largest differences were observed in the anterior part of the vocal folds. Conclusions The average values of OQVSK measurements are comparable despite the use of different measurement software. Software available on the market with a VSK module requires fine-tuning to limit the recording analysis time as much as possible.

Glottal Aerodynamic Measures in Women With Phonotraumatic and Nonphonotraumatic Vocal Hyperfunction.

The purpose of this study was to determine the validity of preliminary reports showing that glottal aerodynamic measures can identify pathophysiological phonatory mechanisms for phonotraumatic and nonphonotraumatic vocal hyperfunction, which are each distinctly different from normal vocal function. Glottal aerodynamic measures (estimates of subglottal air pressure, peak-to-peak airflow, maximum flow declination rate, and open quotient) were obtained noninvasively using a pneumotachograph mask with an intraoral pressure catheter in 16 women with organic vocal fold lesions, 16 women with muscle tension dysphonia, and 2 associated matched control groups with normal voices. Subjects produced /pae/ syllable strings from which glottal airflow was estimated using inverse filtering during /ae/ vowels, and subglottal pressure was estimated during /p/ closures. All measures were normalized for sound pressure level (SPL) and statistically tested for differences between patient and control groups. All SPL-normalized measures were significantly lower in the phonotraumatic group as compared with measures in its control group. For the nonphonotraumatic group, only SPL-normalized subglottal pressure and open quotient were significantly lower than measures in its control group. Results of this study confirm previous hypotheses and preliminary results indicating that SPL-normalized estimates of glottal aerodynamic measures can be used to describe the different pathophysiological phonatory mechanisms associated with phonotraumatic and nonphonotraumatic vocal hyperfunction.

Acoustic Analysis of Voice and Electroglottography in Patients With Laryngopharyngeal Reflux

Laryngopharyngeal reflux (LPR) refers to the flow of gastric acid content into the laryngopharynx. It has been reported that 10% of the patients consulting an otolaryngologist present with this condition. Signs of LPR can be identified during flexible or rigid laryngoscopy. The Voice Handicap Index (VHI) is a reliable tool for detecting the impact of voice disorders, and acoustic assessment of voice including acoustic analysis of voice (AAV) and electroglottography (EGG) provide objective data of voice production and voice disorders. This study aimed to describe changes in AAV, EGG, and VHI in patients who present with LPR compared with a matched control group of healthy subjects. Seventeen patients with LPR were studied. A group of healthy subjects matched by age and gender without any history of voice disorder, LPR, or gastroesophageal reflux disease was assembled. Both groups of patients were studied by VHI, flexible laryngoscopy, AAV, and EGG. All patients with LPR demonstrated abnormal VHI values. Shimmer, jitter, open quotient, and irregularity were significantly increased in the patients with LPR. Nonsignificant correlations were found between VHI scores and abnormal acoustic parameters in patients with LPR. Although abnormal acoustic parameters of patients with LPR were not predictive of the overall VHI score, the abnormal acoustic parameters of patients with LPR suggest a decrease in adequate laryngeal control during phonation.

Open quotients of trivial vector bundles

Given an arbitrary topological complex vector space A, a quotient vector bundle for A is a quotient of a trivial vector bundle π2:A×X→X by a fiberwise linear continuous open surjection. We show that this notion subsumes that of a Banach bundle over a locally compact Hausdorff space X. Hyperspaces consisting of linear subspaces of A, topologized with natural topologies that include the lower Vietoris topology and the Fell topology, provide classifying spaces for various classes of quotient vector bundles, in a way that generalizes the classification of locally trivial vector bundles by Grassmannians. If A is normed, a finer hyperspace topology is introduced that classifies bundles with continuous norm, including Banach bundles, and such that bundles of constant finite rank must be locally trivial.

Computational Modeling of Fluid-Structure-Acoustics Interaction during Voice Production.

The paper presented a three-dimensional, first-principle based fluid–structure–acoustics interaction computer model of voice production, which employed a more realistic human laryngeal and vocal tract geometries. Self-sustained vibrations, important convergent–divergent vibration pattern of the vocal folds, and entrainment of the two dominant vibratory modes were captured. Voice quality-associated parameters including the frequency, open quotient, skewness quotient, and flow rate of the glottal flow waveform were found to be well within the normal physiological ranges. The analogy between the vocal tract and a quarter-wave resonator was demonstrated. The acoustic perturbed flux and pressure inside the glottis were found to be at the same order with their incompressible counterparts, suggesting strong source–filter interactions during voice production. Such high fidelity computational model will be useful for investigating a variety of pathological conditions that involve complex vibrations, such as vocal fold paralysis, vocal nodules, and vocal polyps. The model is also an important step toward a patient-specific surgical planning tool that can serve as a no-risk trial and error platform for different procedures, such as injection of biomaterials and thyroplastic medialization.

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.

Assessment of disordered voices based on an optimized glottal source model

In this paper, a method for the assessment of disordered voices is proposed. A feature named mean opening quotient (MOQ) obtained from the glottal source estimation is used as an acoustic cue to summarize the degree of severity of the voice disorder. The analysis method uses the empirical mode decomposition algorithm to estimate the glottal source excitation signal from the speech signal. The logarithm of the magnitude spectrum of the speech signal is decomposed into oscillatory modes, called intrinsic mode functions, that are clustered into two classes, the spectral envelope and the harmonic component. The exploitation of the phase information jointly with the estimated harmonic component enables the estimation of the glottal source signal. An appropriate parametric model is fitted to the estimated glottal source excitation signal. The optimal parameters of the glottal source excitation model from which the MOQ is defined are obtained by using a genetic algorithm. The presented method is tested on a corpus of natural speech including the vowel [a] uttered by 22 normophonic speakers and 229 speakers with different degrees of dysphonia. Experimental results show that the proposed method is very effective for assessing the degree of severity of the voice disorder.

The Influence of Vowels on Vocal Fold Dynamics in the Tenor's Passaggio

The influence of vowels on the frequency region where registration events in male voices usually occur (passaggio) has not yet been clarified. Particularly, for tenors who frequently have to sing across the passaggio, it might be assumed that the vowel quality has an influence on the stability of phonation. In this investigation, six professionally trained Western classical tenors performed a glide from A3 (220 Hz) to A4 (440 Hz) and were recorded using high-speed videoendoscopy at 20,000 fps via transnasal flexible endoscopy. The participants produced transitions (1) from modal register to falsetto and (2) from modal register to stage voice above the passaggio on the vowels [aː], [iː], and [uː]. Simultaneously, acoustic and electroglottographic (EGG) signals were recorded. The glottal area waveform (GAW) open quotient (OQ), the EGG OQ, and the sample entropy derived from the EGG were calculated and phonovibrograms were established. In comparison to [iː] and [uː], vowel [aː] showed lower values regarding the sample entropy and greater periodicity in the phonovibrograms during the passaggio. For [iː] and [uː], the falsetto showed greater GAW OQ than the stage voice above the passaggio but no great difference for vowel [aː]. There was a good agreement between GAW OQ and EGG OQ for GAW OQ values below .65. However, for values greater than .65, the EGG OQ showed greater disagreement. The data support the hypothesis that the vowel condition influences the phonatory stability concerning the passaggio, suggesting that vowel [aː] is associated with greater phonation stability.

Acoustic Analysis and Electroglottography in Elite Vocal Performers

Acoustic analysis of voice (AAV) and electroglottography (EGG) have been used for assessing vocal quality in patients with voice disorders. The effectiveness of these procedures for detecting mild disturbances in vocal quality in elite vocal performers has been controversial. To compare acoustic parameters obtained by AAV and EGG before and after vocal training to determine the effectiveness of these procedures for detecting vocal improvements in elite vocal performers. Thirty-three elite vocal performers were studied. The study group included 14 males and 19 females, ages 18-40 years, without a history of voice disorders. Acoustic parameters were obtained through AAV and EGG before and after vocal training using the Linklater method. Nonsignificant differences (P > 0.05) were found between values of fundamental frequency (F0), shimmer, and jitter obtained by both procedures before vocal training. Mean F0 was similar after vocal training. Jitter percentage as measured by AAV showed nonsignificant differences (P > 0.05) before and after vocal training. Shimmer percentage as measured by AAV demonstrated a significant reduction (P < 0.05) after vocal training. As measured by EGG after vocal training, shimmer and jitter were significantly reduced (P < 0.05); open quotient was significantly increased (P < 0.05); and irregularity was significantly reduced (P < 0.05). AAV and EGG were effective for detecting improvements in vocal function after vocal training in male and female elite vocal performers undergoing vocal training. EGG demonstrated better efficacy for detecting improvements and provided additional parameters as compared to AAV.

High-speed Videolaryngoscopy: Quantitative Parameters of Glottal Area Waveforms and High-speed Kymography in Healthy Individuals

We conducted a study to obtain quantitative parameters of the vocal dynamic using high-speed videolaryngoscopy and to characterize the vocal fold vibration pattern of healthy individuals by analyzing glottal area waveforms and high-speed kymography. Laryngeal images of 45 healthy individuals were captured using high-speed videolaryngoscopy. The open and speed quotients of the glottal area waveforms and high-speed kymography were obtained and statistically analyzed according to the gender of each individual. Glottal area waveforms revealed average values of 0.85 and 1.16 for open and speed quotients, respectively, for women, and 0.70 and 1.19 for men. Using high-speed kymography, quantitative parameters of open and speed quotients for women were 0.62 and 1.02, respectively, and for men were 0.57 and 1.12. By gender, a significant statistical difference emerged for open quotients obtained from both glottal area waveforms (P = 0.004) and high-speed kymography (P = 0.013). Obtained by using computational tools specifically for analyzing laryngeal images from high-speed videolaryngoscopy, quantitative parameters of glottal area waveforms and high-speed kymography in healthy individuals provide reference data and normality for future studies.

Characteristics of Euphony in Direct and Indirect Mucosal Wave Imaging Techniques

There is a necessity to include objective methods to the study protocol of voice. Such procedure will help not only in diagnosing and monitoring the course of treatment, but also in comparing the results of studies between research centers. Vocal fold mucosal wave characteristics of 70 healthy people were made using videostrobokymographic open quotient (VSKOQ) and electroglottographic quasi-open quotient (EGGQOQ). Statistically significant differences were achieved regarding gender for the averaged values of VSKOQ as well as for values calculated from the posterior part of the vocal folds. A statistically significant correlation between the value of VSKOQ and age was observed for the posterior part of the glottis. Differences between gender and the value of EGGQOQ were observed. No statistically significant correlation between EGGQOQ and age was obtained. VSKOQ and EGGQOQ are parameters characterizing glottal function in a coherent manner. These parameters can be included easily in phoniatric examination and help to objectify glottal function.

Vocal fold vibration and voice quality in the elderly

The vocal fold vibration patterns of incomplete glottal closure, aperiodicity, and asymmetry are characteristic of older adults with normal voice quality. Given that these patterns are also reported in older adults with voice concerns (i.e., age-related dysphonia, presbylarygis, or presbyphonia), the question of whether they relate to voice quality becomes relevant to providers making evaluation and management decisions. METHOD: Thirty-eight adults aged 70 years and older underwent laryngeal high-speed video examination at 4000 frames per second. Analysis included measurements of the glottal closure over time (i.e., open quotient, relative glottal gap), spectral noise (i.e., harmonics-to-deterministic-noise ratio, harmonics-to-noise ratio), and symmetry (i.e., amplitude symmetry, phase symmetry). Multiple regression will be used to compare the high-speed measures to cepstral peak prominence of the acoustic signal and perceived voice quality. Results will be interpreted in terms of how glottal closure and vibratory periodicity and symmetry affect voice quality in elderly speakers. Implications for clinical management will be discussed.

The effect of vocal fold vertical stiffness variation on voice production

A parametric study was conducted using the numerical technique that coupled a three-dimensional continuum vocal fold model with a one-dimensional Bernoulli flow model to investigate the effect of vocal fold vertical stiffness variation on voice production. Vertical stiffness gradient was defined as the ratio of the inferior-superior stiffness difference to the mean stiffness and was introduced in the cover layer. The results showed that increasing the vertical stiffness gradient would increase the peak flow rate and sound intensity and decrease the open quotient and threshold pressure. The effect was found to be more prominent at low subglottal pressures. The underlying mechanism might be that the reduced stiffness at the superior aspect of the vocal fold would allow a larger lateral displacement and result in a larger vibration. Increasing the vertical stiffness gradient was also found to increase the vertical phase difference and glottal divergent angle during the vocal fold vibration. Meanwhile, increasing the vertical stiffness variation only slightly increased the mean flow rate, which is important to maintaining the speech time between breaths.

Immediate Effects of the Vocal Function Exercises Semi-Occluded Mouth Posture on Glottal Airflow Parameters: A Preliminary Study

The study aimed to quantify immediate alterations in the airflow glottogram between the Vocal Function Exercises semi-occluded mouth posture (/ol/ with lip buzz) and the sustained vowel /o/ in individuals with normal voices, and to determine if noted changes were in agreement with established semi-occluded vocal tract aerodynamic theory. Based on semi-occluded vocal tract aerodynamic theory, we hypothesized the following immediate changes in the flow glottogram during the /ol-buzz/ condition: a greater open quotient, a greater skewing quotient, a greater maximum flow declination rate, increased average airflow, decreased peak airflow, and increased minimum airflow. A cohort of eight men with normal voices produced the sustained vowel /o/ and the Vocal Function Exercises semi-occluded mouth posture (/ol-buzz/). Flow glottograms for both conditions were obtained from the inverse-filtered oral airflow signal via a circumferentially vented pneumotachograph mask. Data revealed that open quotient and minimum airflow rates increased significantly between conditions. All other measures trended in the directions predicted by aerodynamic theory, but were not statistically significant. The Vocal Function Exercises semi-occluded mouth posture appeared to provide an effective vocal tract semi-occlusion that immediately altered the flow glottogram in accordance with predictions made by computer-modeled aerodynamic theory.

Oscillatory Characteristics of the Vocal Folds Across the Tenor Passaggio

Recent research has revealed that classically trained tenors tend to constrict epilaryngeal structures when singing in and above the passaggio (ie, the frequency region where register events typically occur). These constrictions complicate visibility of vocal fold oscillatory patterns with transoral rigid high-speed video endoscopy, thus limiting the current understanding of laryngeal dynamics in the passaggio region of tenors. This investigation analyzed seven professionally trained western classical tenors using high-speed digital imaging (HSDI) at 20,000 frames per second via transnasal flexible endoscopy. The participants produced transitions (a) from modal to falsetto register and (b) from modal to stage voice above the passaggio (SVaP) during ascending pitch glides from A3 (220 Hz) to A4 (440 Hz) on vowel /i/. HSDI data were complemented by simultaneous acoustic and electroglottographic recordings. For many subjects both transition types were associated with constrictions of the epilaryngeal structures during the pitch glide. These constrictions appeared to be more distinct for the SVaP than for falsetto. No major irregularities of vocal fold oscillations in the sense of fundamental frequency jumps were observed for either transition type. However, during the transitions, the open quotient derived from the glottal area waveform (OQGAW) increased; in falsetto, the OQGAW was greater and the electroglottographic cepstral peak prominence was lower than in SVaP. Epilaryngeal constrictions should be considered typical for tenors singing at high fundamental frequencies. Vocal fold oscillatory patterns are changing not only for the register shift from modal to falsetto but also for the transition from modal to SVaP, indicating a need for laryngeal adjustments during these transitions.

Quantitative assessment of videolaryngostroboscopic images in patients with glottic pathologies

Introduction: Digital imaging techniques enable exploration of novel visualization modalities of the vocal folds during phonation and definition of parameters, facilitating more precise diagnosis of voice disorders.Aim: Application of computer vision algorithms for analysis of videolaryngostroboscopic (VLS) images aimed at qualitative and quantitative description of phonatory vibrations.Materials and methods: VLS examinations were conducted for 45 females, including 15 subjects with vocal nodules, 15 subjects with glottal incompetence, and 15 normophonic females. The recorded VLS images were preprocessed, the glottis area was segmented out, and the glottal cycles were identified. The glottovibrograms were built, and then the glottal area waveforms (GAW) were quantitatively described by computing the following parameters: open quotient (OQ), closing quotient (CQ), speed quotient (SQ), minimal relative glottal area (MRGA), and a new parameter termed closure difference index (CDI).Results: Profiles of the glottal widths assessed along the glottal length differentiated the study groups (P < 0.001). Moreover, it was shown that the OQ, CQ, CDI, and MRGA indices can be considered as viable parameters for quantifying kinematics of the vocal folds for normophonic subjects and patients with diagnosed vocal nodules and glottal incompetence (P < 0.001).Conclusions: Computer image processing and analysis methods applied to videolaryngostroboscopic images allow for their quantitative assessment. Computation of the size-related and time-related parameters characterizing glottic pathologies is of interest for evidence-based voice diagnostics. Results of the performed ROC curve analysis suggest that the evaluated parameters can distinguish patients with voice disorders from normophonic subjects.

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

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

The perception of breathy voice in Gujarati

Breathy voice, also referred to as murmur, is characterized by an increased open quotient and increased airflow. Acoustical correlates of breathiness include an increased spectral slope, most notably as measured by H1-H2 and H1-A3, as well as an increase in noise as measured by harmonics-to-noise ratio and cepstral peak prominence. Gujarati is relatively unique in that it contains phonemic breathiness in both consonants and vowels, creating meaningfully different Cɦ V and CV̤ sequences. Acoustic analysis of this contrast indicates that while the acoustic correlates of breathiness are consistent across these two sequences, there are differences in both the timing and magnitude of the cues of breathiness (Esposito and Khan 2012). Perceptual studies have indicated that speakers of languages with phonemic breathiness are capable of reliably differentiating breathy and modal sounds, but no study to date has addressed the perceptual salience of the timing and degree differences associated with breathiness in consonants versus vowels. The present study addresses the potential confusability of Cɦ V and CV̤ sequences in Gujarati through a series of perception tasks. Results indicate that there is an asymmetrical relationship between Cɦ V and CV̤ sequences that may be attributable to differences in the magnitude and timing of acoustic cues.