Vocal Fold Thickness Research Articles

Degree of Breathiness in a Synthesized Voice Signal as it Differentiates Masculine versus Feminine Voices

Most studies determining speakers' perceived gender as binarily female or male are reliant on F0 perception, although other vocal parameters may also contribute to the perception of gender. The current study focused on the impact of breathiness on the perception of speakers' gender as a biological variable (feminine or masculine). n=31 normal hearing, native English speakers, 18 female, 13 male, mean age 23 (SD=3.54), were auditorily and visually trained in and then took part in a categorical perception task. A continuum of nine samples of the word "hello", was created in an airway modulation model of speech and voice production. Resting vocal fold length, resting vocal fold thickness, F0, and vocal tract length were fixed. Glottal width at the vocal process, posterior glottal gap, and bronchial pressure were continually modified for all stimuli. Each stimulus was randomly presented 30 times within each of the fiveblocks (150 presentations in total). Participants rated stimuli as binarily female or male. Showed a sigmoidal shift in breathiness along the continuum between perceived feminine or masculine voicing. This shift was evident at stimuli four and five, indicating a nonlinear, discrete perception of breathiness among participants. Response times were also significantly slower in these two stimuli, suggesting a categorical perception of breathiness among participants. Breathiness created by the change in glottal width of at least 0.21cm may influence the perception of a speaker's perceived gender.

Gender in human phonation: Fluid–structure interaction and vocal fold morphology

This paper aims to examine the effects of variations in the vocal fold (VF) morphological features associated with gender on glottal aerodynamics and tissue deformation. Nine three-dimensional geometries of the VFs in the larynx are created with various VF lengths, thicknesses, and depths to perform a parametric analysis according to gender-related geometrical parameters. The computational model is incorporated in a fluid–structure interaction methodology by adopting the transient Navier–Stokes equations to model airflow through the larynx and considering a linear elasticity model for VF dynamics. The model predictions, such as aerodynamic data through the larynx, glottal airflow, and VF deformations, are analyzed. The comparison of the simulation results for the nine cases supports the hypothesis that gender differences in laryngeal dimensions remarkably influence the glottal airflow and deformation of the VFs. Decreasing VF thickness and increasing its length corresponds to a noticeable increase in maximum tissue displacement, while variations in depth affect the flow rate significantly in the small and large larynges. Conversely, we observed that the pressure drop at the glottis is nearly independent of the VF length. A comparison of the glottal area with published imaging data illustrated a direct correlation between the glottal configuration and the morphology of the VFs.

Oral vibratory sensations during voice production at different laryngeal and semi-occluded vocal tract configurations.

Voice therapy often emphasizes vibratory sensations in the front part of the vocal tract during phonation to improve vocal efficiency. It remains unclear what laryngeal and vocal tract adjustments are elicited in speakers by this emphasis on oral vibratory sensations. Using a three-dimensional phonation model, this study aims to identify laryngeal and epilaryngeal adjustments that might produce maximal oral vibratory sensations during phonation, as quantified by the oral sound pressure level (SPL), and thus are likely to be elicited in voice therapy at different semi-occluded vocal tract configurations. Results show that maximum oral SPL occurs at intermediate vocal fold adduction configurations characterized by a trade-off between glottal gap and vocal fold vertical thickness. Epilaryngeal tube narrowing further increases the oral SPL in an open vocal tract, but has little effect on oral SPL in semi-occluded vocal tracts. Laryngeal and epilaryngeal configurations producing the maximum oral SPL generally have lower peak vocal fold contact pressure when producing a target output SPL. These favorable configurations are more easily identified in open vocal tracts than semi-occluded vocal tracts. However, semi-occlusion increases both the mean and dynamic oral pressure, which may familiarize speakers with oral vibratory sensations and facilitate adoption of favorable laryngeal configurations.

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

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

Contribution of vocal fold thickness to gender perception

Male vocal folds are often longer and thicker than female vocal folds. The length difference is generally considered responsible for the notable difference in fundamental frequency between men and women, which plays an important role in gender perception. The role of the thickness difference in gender perception is less clear, although our recent studies demonstrated an important role of thickness in the control of voice quality. The goal of this study is to investigate the contribution of changes in vocal fold thickness and stiffness to gender perception. Synthetic voices were generated using a three-dimensional vocal fold model with parametric variations in vocal fold geometry, stiffness, adduction, and subglottal pressure. The vocal tract was kept constant in order to focus on the contribution of the voice source. Listening subjects were asked to judge speaker gender in a multiple choice task. Preliminary results showed a significant effect of vocal fold thickness and transverse stiffness on gender perception, with voices produced by thicker vocal folds and lower transverse stiffnesses more likely to be judged as male. Acoustically, gender perception scores were correlated with the fundamental frequency and spectral shape. [Work supported by NIH.]

Interaction between epilaryngeal and laryngeal adjustments in regulating vocal fold contact pressure.

This study investigates the peak vocal fold contact pressure at different conditions of epilaryngeal narrowing and laryngeal adjustments. The results show that for a given subglottal pressure, the peak vocal fold contact pressure may increase or decrease with epilaryngeal narrowing, depending on a complex interaction between vocal fold vertical thickness, initial glottal angle, and subglottal pressure. However, epilaryngeal narrowing also significantly increases vocal efficiency so that for a target sound pressure level, the peak vocal fold contact pressure decreases with epilaryngeal narrowing. Overall, the peak vocal fold contact pressure and respiratory effort can be minimized by epilaryngeal narrowing, adopting a small initial glottal angle, and an intermediate vocal fold thickness.

Gender Recognition of Speech Signal using KNN and SVM

Human speech is formulated by the vibration of vocal cord of human being consisting of different sounds for speaking, singing, expressing emotions and ideas, etc .The vocal cord being an important source of sound with human voice as a part of human sound synthesis [3] [5]. Differences in human speech for male and female are due to physiological difference such as vocal fold thickness or vocal tract length. The vocal tracts of male are mostly longer in comparison to vocal tracts of female. With advancing technology and more and more usage of human computer interaction (HCI) based systems, the speech processing plays an important role in enhancing the HCI system [2] [4]. The reason for development of gender recognition system is its used in gender based virtual assistants, telephonic surveys and voice controlled automatic systems.

Characterization of intrauterine growth, proliferation and biomechanical properties of the murine larynx.

Current research approaches employ traditional tissue engineering strategies to promote vocal fold (VF) tissue regeneration, whereas recent novel advances seek to use principles of developmental biology to guide tissue generation by mimicking native developmental cues, causing tissue or allogenic/autologous progenitor cells to undergo the regeneration process. To address the paucity of data to direct VF differentiation and subsequent new tissue formation, we characterize structure-proliferation relationships and tissue elastic moduli over embryonic development using a murine model. Growth, cell proliferation, and tissue biomechanics were taken at E13.5, E15.5, E16.5, E18.5, P0, and adult time points. Quadratic growth patterns were found in larynx length, maximum transverse diameter, outer dorsoventral diameter, and VF thickness; internal VF length was found to mature linearly. Cell proliferation measured with EdU in the coronal and transverse planes of the VFs was found to decrease with increasing age. Exploiting atomic force microscopy, we measured significant differences in tissue stiffness across all time points except between E13.5 and E15.5. Taken together, our results indicate that as the VF mature and develop quadratically, there is a concomitant tissue stiffness increase. Greater gains in biomechanical stiffness at later prenatal stages, correlated with reduced cell proliferation, suggest that extracellular matrix deposition may be responsible for VF thickening and increased biomechanical function, and that the onset of biomechanical loading (breathing) may also contribute to increased stiffness. These data provide a profile of VF biomechanical and growth properties that can guide the development of biomechanically-relevant scaffolds and progenitor cell differentiation for VF tissue regeneration.

Laryngeal strategies to minimize vocal fold contact pressure and their effect on voice production.

The goal of this study is to identify laryngeal strategies that minimize vocal fold contact pressure while producing a target sound pressure level (SPL) using a three-dimensional voice production model. The results show that while the subglottal pressure and transverse stiffness can be manipulated to reduce the peak contact pressure, such manipulations also reduce the SPL, and are thus less effective in reducing contact pressure in voice tasks targeting a specific SPL level. In contrast, changes in the initial glottal angle and vocal fold vertical thickness that reduce the contact pressure also increase the SPL. Thus, in voice tasks targeting a specific SPL, such changes in the initial glottal angle and vertical thickness also lower the subglottal pressure, which further reduces the peak contact pressure. Overall the results show that for voice tasks with a target SPL level, vocal fold contact pressure can be significantly reduced by adopting a barely abducted glottal configuration or reducing the vocal fold vertical thickness. Aerodynamic measures are effective in identifying voice production with large initial glottal angles, but by themselves alone are not useful in differentiating hyperadducted vocal folds from barely abducted vocal folds, which may be better differentiated by closed quotient and voice type measures.

Quantitative Measurement of the Three-dimensional Structure of the Vocal Folds and Its Application in Identifying the Type of Cricoarytenoid Joint Dislocation

The objective of this study was to quantitatively measure the three-dimensional (3D) structure of the vocal folds in normal subjects and in patients with different types of cricoarytenoid dislocation. We will analyze differences in parameters between the groups and also determine if any morphologic parameters possess utility in distinguishing the type and the degree of cricoarytenoid dislocation. This retrospective study was conducted using university hospital data. Subjects' larynges were scanned using dual-source computed tomography (CT). The normal subjects were divided into deep-inhalation and phonation groups, and patients with cricoarytenoid joint dislocation were divided into anterior-dislocation and posterior-dislocation groups. Membranous vocal fold length and width were measured directly on the thin-section CT images. Vocal fold and airway 3D models were constructed using Mimics software and used in combination to measure vocal fold thickness, subglottal convergence angle, and oblique angle of the vocal folds. The phonation group displayed a greater vocal fold width, greater oblique angle, thinner vocal folds, and a smaller subglottal convergence angle than those of the deep-inhalation group (P < 0.05). The anterior-dislocation group displayed a smaller oblique angle and subglottal convergence angle than the posterior-dislocation group (P < 0.05). The 3D structure of the vocal folds during deep inhalation and phonation can be accurately measured using dual-source CT and laryngeal 3D reconstruction. As the anterior-dislocation group yielded negative values for the oblique angle and the posterior-dislocation group yielded positive values, the oblique angle of the vocal folds may possess utility for distinguishing the type and for quantitatively determining the degree of cricoarytenoid dislocation.

An empirical model linking intrinsic laryngeal muscle activation to vocal fold geometry and stiffness

Although vocal fold vibration and the resulting voice production depend on the geometry and mechanical properties of the vocal folds, control of voice is achieved through laryngeal muscle activation, which postures the vocal folds into desired geometry and mechanical properties. Such posturing process is known to cause simultaneous changes in vocal fold position, geometry, stiffness, and tension, which has been hypothesized to be a possible origin of vocal registers. Understanding such co-variations in vocal fold geometry and mechanical properties is thus critical to our understanding of human voice production and control, and the development of muscularly controlled, computationally efficient models of phonation. In this study, an empirical model is developed to link the glottal gap, vocal fold length, vocal fold vertical thickness, and the mechanical properties of the vocal fold to the activation levels of the cricothyroid, thyroarytenoid, lateral cricoarytenoid, interarytenoid, and posterior cricoarytenoid muscles, based on data from in vivo larynx experiments. Combined with a continuum model of phonation, this model is used to investigate muscular control of pitch and vocal registers and the preliminary results are discussed.

Cause-effect relationship between vocal fold physiology and voice production in a three-dimensional phonation model

The goal of this study is to better understand the cause-effect relation between vocal fold physiology and the resulting vibration pattern and voice acoustics. Using a three-dimensional continuum model of phonation, the effects of changes in vocal fold stiffness, medial surface thickness in the vertical direction, resting glottal opening, and subglottal pressure on vocal fold vibration and different acoustic measures are investigated. The results show that the medial surface thickness has dominant effects on the vertical phase difference between the upper and lower margins of the medial surface, closed quotient, H1-H2, and higher-order harmonics excitation. The main effects of vocal fold approximation or decreasing resting glottal opening are to lower the phonation threshold pressure, reduce noise production, and increase the fundamental frequency. Increasing subglottal pressure is primarily responsible for vocal intensity increase but also leads to significant increase in noise production and an increased fundamental frequency. Increasing AP stiffness significantly increases the fundamental frequency and slightly reduces noise production. The interaction among vocal fold thickness, stiffness, approximation, and subglottal pressure in the control of F0, vocal intensity, and voice quality is discussed.

Configuration of vocal folds during and after tube phonation in patients with voice disorders: A computerized tomographic study

Purpose: The study aims to observe whether any systematic change in vocal fold configuration occurs during and after phonation into a tube using computerized tomography (CT). Materials and Methods: Ten participants diagnosed with functional dysphonia were included in the study. CT was performed when participants produced the sound (a:), phonated into a drinking straw and when repeating (a:) after the exercise. Similar procedure was performed with a stirring straw after 20 min of vocal rest. Anatomic variables included: (1) glottal area, (2) glottal width, (3) vertical vocal fold thickness, (4) vocal fold area, and (5) vocal fold length. Each vocal fold was separately analyzed. Results: Only glottal area for stirring straw was statistically different throughout the three time points. This variable increased during tube phonation compared to conditions pre- and post-tube. Discussion: Since vocal fold length did not change during tube phonation, the increment in glottal area was likely due to increased amplitude of vibration. Increased vibratory amplitude has been found in previous studies with high-speed imaging, suggesting an increased subglottic pressure. From the physiologic point of view, transglottal pressure plays an important role in vocal fold amplitude of vibration. Conclusions: Tube phonation seems to cause increased glottal area during exercise. This change is more prominent during exercise with a higher degree of airflow resistance. Therefore, the degree of flow resistance is an important clinical variable to be considered when choosing the right voice exercises regarding the voice status/phonatory pattern of patients during voice therapy.

Interrater Reliability in Analysis of Laryngoscopic Features for Unilateral Vocal Fold Paresis

The diagnosis of paresis in patients with vocal fold motion impairment remains a challenge. In particular, laryngoscopy examination may result in significant disagreement in diagnosis among providers. We hypothesize that systematically evaluating for a standard set of clinical parameters will increase the diagnostic concordance among providers. Prospective case series conducted at a Tertiary referral Laryngology office. Two laryngologists (rater 1) and two trainees (rater 2) rated laryngoscopy findings in 19 patients suspected of paresis. The diagnosis was confirmed with laryngeal electromyogram. A standard set of 27 ratings was used for each examination that included movement, laryngeal configuration, and stroboscopy signs. A kappa coefficient was calculated for agreement in laryngoscopy findings and effectiveness in predicting the laterality of paresis. A substantial agreement (kappa coefficient>0.61) existed between the raters for vocal fold length, vocal fold thickness, bowing, and reduction in movement. A moderate agreement (kappa coefficient>0.41) existed between raters for piriform opening and reduced kinesis. The senior author was accurately able to diagnose the side of paresis in 89.5% of cases for a kappa coefficient of 0.78, whereas the trainees correctly predicted the side of paresis in 63.1% for a kappa coefficient of 0.35. The raters agreed on the diagnosis in 73.7% of cases for a kappa coefficient of 0.50. Using a standard set of laryngoscopy findings may improve the provider's ability to identify the laterality of vocal fold paresis and increase interrater reliability compared with other series.

Vibrational and acoustic consequences of changes in subglottal pressure, vocal fold stiffness, vocal fold approximation, and vocal fold thickness

Using a three-dimensional continuum model of phonation, this study investigates the effects of changes in subglottal pressure, vocal fold approximation and stiffening, and vocal fold medial surface thickness on vocal fold vibration and acoustics. The results show that increasing subglottal pressure leads to more or less uniform increase in harmonic energy across a very large frequency range as well as significant increase in noise production. Reduced noise production can be achieved by increasing medial surface thickness, vocal fold approximation, or vocal fold stiffening. Increasing vocal fold thickness and stiffness also lead to increased production of high-frequency harmonics. The closed quotient of vocal fold vibration depends primarily on the medial surface thickness of the vocal fold, with the closed quotient increasing with increasing thickness. The closed quotient also slightly decreases with increasing subglottal pressure, but increases with increasing vocal fold approximation and stiffening. These results suggest that, in addition to increasing subglottal pressure, vocal loudness can be also increased by increasing vocal fold thickness, approximation and/or stiffening to increase production of higher-order harmonics and reduce noise production, which leads to a perceived increase in vocal intensity. [Work supported by NIH.]

Vocal Fold Adjustment Caused by Phonation Into a Tube: A Double-Case Study Using Computed Tomography

Phonation into a tube is a widely used method for vocal training and therapy. Previous studies and practical experience show that the phonation becomes easier and louder after such an exercise. The purpose of this study was to find out whether there are systematic changes in the vocal fold adjustment after the exercise. Two volunteer subjects (1 male and 1 female) without voice disorders were examined with computed tomography (CT). Both produced a sustained vowel [a:] at comfortable pitch and loudness before and after the tube phonation and a vowel-like phonation into the tube. Computed tomography (CT) scans were obtained before, during, and after the exercise, twice for each condition. The gathered CT images were used for measurements of vertical vocal fold thickness, bulkiness, length, and glottal width. No prominent trends common to both subjects were found in vocal fold adjustment during and after the phonation into the tube. Variability observed under the same conditions was usually of the same magnitude as the changes before and after the tube phonation. Changes in vocal tract configuration observed after the resonance tube exercises in previous related studies were more prominent than the changes in vocal fold configuration observed here.

Hoarseness secondary to haemodialysis: case report and literature review

Hoarseness is common and can have a major impact on patients' quality of life. We report a rare case of hoarseness secondary to haemodialysis. A 62-year-old man described developing transient hoarseness after haemodialysis sessions, which he underwent three times weekly. Fibre-optic nasendoscopy showed incomplete glottis closure due to bowing of the vocal folds. A computed tomography scan of the neck and thorax was unremarkable. Speech therapy was unhelpful. The renal physicians concluded that no change could be made to his dialysis regime. The patient subsequently underwent injection laryngoplasty with calcium hydroxylapatite, with marked improvement of his symptoms. A literature search found one relevant article reporting that 60 per cent of patients suffered post-dialysis hoarseness and decreased vocal fold thickness. It is postulated that dialysis causes dehydration of Reinke's space, affecting vocal fold thickness and the patient's voice. Hoarseness caused by haemodialysis is uncharted territory. Further research is required to determine its prevalence and contributing factors.

Vocal Fold Mass Is Not A Useful Quantity for Describing F 0 in Vocalization

Confusion exists about the effect of mass and size of the vocal folds on fundamental frequency (F0) of phonation. In particular, greater vocal fold thickness is often assumed to be associated with lower F0. The purpose here is to show that such a relationship does not exist and that F0 should be conceptualized with quantities other than mass (i.e., length and tissue stress). Arguments are made on the basis of fundamental laws of mechanics (point-mass vs. distributed mass). In speech science, phonetics, and animal vocalization disciplines, instruction should shift away from point-mass descriptions of vocal fold tissue and toward an understanding of mode frequencies in an elastic continuum.

Three‐Dimensional Conformation of the Injected Bolus in Vocal Fold Injections in a Cadaver Model

To determine the 3-dimensional (3D) conformation of the injected bolus in the larynx in vocal fold injections, to understand how the bolus interacts spatially with elements of the laryngeal framework, and to relate the above to clinical observations in performing vocal fold injections. Excised cadaveric larynx study. Laboratory. Vocal folds of 12 human excised cadaveric larynges were injected with calcium hydroxylapatite. High-resolution computed tomography scans were obtained of the injected larynges. Densities corresponding to the injected bolus and the laryngeal framework were extracted and processed with MATLAB routines to generate selective 3D reconstructions of the injected bolus within the laryngeal framework. Histology analysis was also performed to correlate with observations from the 3D reconstructions. Boluses injected into the lateral aspect of the thyroarytenoid muscle tended to be irregularly shaped, appeared to fill up the paraglottic space, and were associated with significant muscle compression. The vertical thickness of the injected boluses averaged 9.5 mm for lateral boluses and 7.6 mm for medial boluses, which were comparable to the vertical thickness of uninjected vocal folds. Laterally injected boluses are shaped by spatial constraints imposed by elements of the laryngeal framework. Compression of vocal fold muscle may be a mechanism accounting for stiffness from overinjection. The irregular shapes of some boluses may affect the outcome of subsequent medialization attempts. Injections may enhance the vocal fold contact height as a favorable effect beyond simple medialization.

Phonation threshold pressure predictions using viscoelastic properties up to 1,400 Hz of injectables intended for Reinke's space

Viscoelastic properties of numerous vocal fold injectables have been reported but not at speaking frequencies. For materials intended for Reinke's space, ramifications of property values are of great concern because of their impact on ease of voice onset. Our objectives were: 1) to measure viscoelastic properties of a new nonresorbing carbomer and well-known vocal fold injectables at vocalization frequencies using established and new instrumentation, and 2) to predict phonation threshold pressures using a computer model with intended placement in Reinke's space. Rheology and phonation threshold pressure calculations. Injectables were evaluated with a traditional rotational rheometer and a new piezo-rotary vibrator. Using these data at vocalization frequencies, phonation threshold pressures (PTP) were calculated for each biomaterial, assuming a low dimensional model with supraglottic coupling and adjusted vocal fold length and thickness at each frequency. Results were normalized to a nominal PTP value. Viscoelastic data were acquired at vocalization frequencies as high as 363 to 1,400 Hz for six new carbomer hydrogels, Hylan B, and Extracel intended for vocal fold Reinke's space injection and for Cymetra (lateral injection). Reliability was confirmed with good data overlap when measuring with either rheometer. PTP predictions ranged from 0.001 to 16 times the nominal PTP value of 0.283 kPa. Accurate viscoelastic measurements of vocal fold injectables are now possible at physiologic frequencies. Hylan B, Extracel, and the new carbomer hydrogels should generate easy vocal onset and sustainable vocalization based on their rheologic properties if injected into Reinke's space. Applications may vary depending on desired longevity of implant. Laryngoscope, 2010.