Direct-numerical simulation of the glottal jet and vocal-fold dynamics in a three-dimensional laryngeal model.
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ABSTRACT:
SUBMITTER: Zheng X
PROVIDER: S-EPMC3155594 | biostudies-other | 2011 Jul
REPOSITORIES: biostudies-other
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Project description:MotivationHuman voice is generated in the larynx by the two oscillating vocal folds. Owing to the limited space and accessibility of the larynx, endoscopic investigation of the actual phonatory process in detail is challenging. Hence the biomechanics of the human phonatory process are still not yet fully understood. Therefore, we adapt a mathematical model of the vocal folds towards vocal fold oscillations to quantify gender and age related differences expressed by computed biomechanical model parameters.MethodsThe vocal fold dynamics are visualized by laryngeal high-speed videoendoscopy (4000 fps). A total of 33 healthy young subjects (16 females, 17 males) and 11 elderly subjects (5 females, 6 males) were recorded. A numerical two-mass model is adapted to the recorded vocal fold oscillations by varying model masses, stiffness and subglottal pressure. For adapting the model towards the recorded vocal fold dynamics, three different optimization algorithms (Nelder-Mead, Particle Swarm Optimization and Simulated Bee Colony) in combination with three cost functions were considered for applicability. Gender differences and age-related kinematic differences reflected by the model parameters were analyzed.Results and conclusionThe biomechanical model in combination with numerical optimization techniques allowed phonatory behavior to be simulated and laryngeal parameters involved to be quantified. All three optimization algorithms showed promising results. However, only one cost function seems to be suitable for this optimization task. The gained model parameters reflect the phonatory biomechanics for men and women well and show quantitative age- and gender-specific differences. The model parameters for younger females and males showed lower subglottal pressures, lower stiffness and higher masses than the corresponding elderly groups. Females exhibited higher subglottal pressures, smaller oscillation masses and larger stiffness than the corresponding similar aged male groups. Optimizing numerical models towards vocal fold oscillations is useful to identify underlying laryngeal components controlling the phonatory process.
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Project description:Male Rocky Mountain elk (Cervus elaphus nelsoni) produce loud and high fundamental frequency bugles during the mating season, in contrast to the male European Red Deer (Cervus elaphus scoticus) who produces loud and low fundamental frequency roaring calls. A critical step in understanding vocal communication is to relate sound complexity to anatomy and physiology in a causal manner. Experimentation at the sound source, often difficult in vivo in mammals, is simulated here by a finite element model of the larynx and a wave propagation model of the vocal tract, both based on the morphology and biomechanics of the elk. The model can produce a wide range of fundamental frequencies. Low fundamental frequencies require low vocal fold strain, but large lung pressure and large glottal flow if sound intensity level is to exceed 70 dB at 10 m distance. A high-frequency bugle requires both large muscular effort (to strain the vocal ligament) and high lung pressure (to overcome phonation threshold pressure), but at least 10 dB more intensity level can be achieved. Glottal efficiency, the ration of radiated sound power to aerodynamic power at the glottis, is higher in elk, suggesting an advantage of high-pitched signaling. This advantage is based on two aspects; first, the lower airflow required for aerodynamic power and, second, an acoustic radiation advantage at higher frequencies. Both signal types are used by the respective males during the mating season and probably serve as honest signals. The two signal types relate differently to physical qualities of the sender. The low-frequency sound (Red Deer call) relates to overall body size via a strong relationship between acoustic parameters and the size of vocal organs and body size. The high-frequency bugle may signal muscular strength and endurance, via a 'vocalizing at the edge' mechanism, for which efficiency is critical.
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Project description:We have developed a novel surgical/computational model for the investigation of unilateral vocal fold paralysis (UVFP) which will be used to inform future in silico approaches to improve surgical outcomes in type I thyroplasty. Healthy phonation (HP) was achieved using cricothyroid suture approximation on both sides of the larynx to generate symmetrical vocal fold closure. Following high-speed videoendoscopy (HSV) capture, sutures on the right side of the larynx were removed, partially releasing tension unilaterally and generating asymmetric vocal fold closure characteristic of UVFP (sUVFP condition). HSV revealed symmetric vibration in HP, while in sUVFP the sutured side demonstrated a higher frequency (10 - 11%). For the computational model, ex vivo magnetic resonance imaging (MRI) scans were captured at three configurations: non-approximated (NA), HP, and sUVFP. A finite-element method (FEM) model was built, in which cartilage displacements from the MRI images were used to prescribe the adduction and the vocal fold deformation was simulated before the eigenmode calculation. The results showed that the frequency comparison between the two sides were consistent with observations from HSV. This alignment between the surgical and computational models supports the future application of these methods for the investigation of treatment for UVFP.
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Project description:Paracoccidioidomycosis (PCM) is a systemic granulomatous disease caused by Paracoccidioides brasiliensis or P. lutzii. It is a neglected tropical infectious disease that poses a major public health burden in endemic areas of Latin America. Mucosae of the upper digestive and respiratory tracts are commonly involved and many patients have disease at multiple mucosal sites, with or without lung involvement. Mucosal PCM presenting as solitary true vocal fold disease is relatively rare. We present the case of a 67-year-old Brazilian forest guard who presented with a 6-month history of hoarseness and globus pharyngeus due to a solitary left true vocal fold infiltration and vegetation diagnosed as PCM. Silent pulmonary disease was also present. A laryngoscopy video is offered as supplemental material to this report. He completely remitted after surgical removal and amphotericin B deoxycholate treatment.
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Project description:Purpose of reviewPresent the state-of-the-art overview of laryngeal pacing for treatment of bilateral vocal fold paralysis. A minimally invasive unilateral pacing system and a fully implantable bilateral pacing system are currently in clinical trials. The relative advantages and disadvantages of each are discussed.Recent findingsResearch in functional electrical stimulation for the reanimation of the posterior cricoarytenoid muscle has successfully translated from animal models to human clinical trials for unilateral pacing and bilateral pacing. Current findings suggest unilateral pacing in humans significantly improves ventilation but only marginally better than cordotomy. Bilateral pacing in canines increases glottal opening greater than 2-fold over unilateral pacing and restores exercise tolerance to normal.SummaryUnilateral pacing can be considered a breathing assist device and may not be appropriate for active individuals. Bilateral pacing may be preferable for patients who wish to engage in strenuous exercise. Minimally invasive systems may be ideal for patients who prefer less invasive implantation and are not concerned with cosmesis. Fully implantable pacing systems offer greater electrode redundancy and stability, resulting in a system that is robust against electrode migration or damage.
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Project description: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.
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Project description:Vocal cord healing is a dynamic process, and many genes and proteins are involved, which play varying roles at different regeneration stages after injury. Previous studies have shown that inflammatory responses occur at the early stage of vocal cord injury, where the fibroblasts proliferate exuberantly with intensive secretion and deposition of ECM. These activities reach the peak at 3-7 days and their intensity begins to decline 15 days later. A study based on the dermal system has shown that ECM remodeling during the repair of injury can last for several months. However, few studies have been conducted as to the dynamic changes of gene expressions and signaling pathway during the healing process of vocal cord injury. Plotting these changes will facilitate the understanding about the physiological changes during healing and the identification of key time points and target genes in fibrosis formation.
2019-10-26 | GSE139383 | GEO
Project description:Previous investigations using in vivo models to study the role of intrinsic laryngeal muscles in phonation have used neuromuscular stimulation to study voice parameters. However, these studies used coarse stimulation techniques using limited levels of neuromuscular stimulation. In the current investigation, a technique for fine control of laryngeal posturing was developed using graded stimulation of the laryngeal nerves. Vocal fold strain history to graded stimulation and a methodology for establishing symmetric laryngeal activation is presented. This methodology has immediate applications for the study of laryngeal paralysis and paresis, as well as general questions of neuromuscular control of the larynx.
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Project description:Vocal cord healing is a dynamic process, and many genes and proteins are involved, which play varying roles at different regeneration stages after injury. Previous studies have shown that inflammatory responses occur at the early stage of vocal cord injury, where the fibroblasts proliferate exuberantly with intensive secretion and deposition of ECM. These activities reach the peak at 3-7 days and their intensity begins to decline 15 days later. A study based on the dermal system has shown that ECM remodeling during the repair of injury can last for several months. However, few studies have been conducted as to the dynamic changes of gene and microRNA expressions during the healing process of vocal cord injury. Plotting these changes will facilitate the understanding about the physiological changes during healing and the identification of key time points and target genes and microRNAs in fibrosis formation.
2020-03-25 | GSE147473 | GEO
Project description:We used microarrays to characterize transcriptome profiles of rat vocal fold tissue following surgical injury (vs. naive tissue); rat vocal fold fibroblasts harvested from scar tissue at the 60 d time point (vs. naive fibroblasts); rat vocal fold scar fibroblasts treated with siRNA against the collagen chaperone protein rat gp46 (vs. scramble siRNA). Adult Fischer 344 rat vocal fold tissue was harvested at 3, 14, and 60 days following surgical injury (control = age-matched naive tissue); rat vocal fold scar fibroblasts were obtained via explant culture of tissue obtained 60 days following surgical injury and harvested at 80% confluence during passage 1 (control = age-matched naive rat vocal fold fibroblasts); rat vocal fold scar fibroblasts were treated for 1 h with 50 nM liposome-delivered siRNA against rat gp46 when 80% confluent at passage 1, cultured for an additional 24 h in fresh media, then harvested (control = rat vocal fold scar fibroblasts treated with 50 nM liposome-delivered scramble siRNA).
2014-10-09 | E-GEOD-62204 | biostudies-arrayexpress