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Computational Methods and Engineering Solutions to Voice
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Computational Methods and Engineering Solutions to Voice

A special issue of Applied Sciences (ISSN 2076-3417). This special issue belongs to the section "Acoustics and Vibrations".

Deadline for manuscript submissions: closed (31 May 2019) | Viewed by 57985

Special Issue Editor

Prof. Dr. Michael Döllinger

E-Mail Website
Guest Editor
Division of Phoniatrics and Pediatric Audiology, Department of Otorhinolaryngology, Head and Neck Surgery, Medical School, Friedrich-Alexander-University Erlangen-Nürnberg, 91054 Erlangen, Germany
Interests: FSAI in voice production; clinical transfer of new analysis methods and technologies
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

Today, voice and speech research is by far not limited to acoustic, medical and clinical studies and investigations. Approaches from different fields like mathematics, computer science, fluid dynamics, mechatronics and biology are widely applied to achieve new insight into and better understanding of the physiological and pathological laryngeal processes within voice and speech production. Based on fruitful interdisciplinary working research groups, many new approaches have been suggested during the last decade. This includes for example highly advanced numerical models (FEM/FVM models) as well as tissue engineering and data analysis approaches. The purpose of this Special Issue is to provide an overview of the newest and most innovative techniques applied in our field. Young colleagues are especially encouraged to submit their work. Authors are invited to submit their work related to the following topics, applying mathematical, engineering, computer science and biological methods, within the field of voice and speech production:

  • Computational modeling
  • Experimental modeling 
  • Computational fluid dynamics
  • Fluid–structure–acoustic interaction
  • Image processing
  • Advanced data analysis
  • New technologies
  • Tissue engineering
  • Molecular biology

Prof. Dr. Michael Döllinger
Guest Editor

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Applied Sciences is an international peer-reviewed open access semimonthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2400 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • Computational modeling 
  • Experimental modeling
  • Computational fluid dynamics 
  • Fluid–structure–acoustic interaction 
  • Image processing 
  • Advanced data analysis 
  • New technologies 
  • Tissue engineering
  • Molecular biology

Published Papers (15 papers)

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Research

16 pages, 4684 KiB  
Article
Mapping Thyroarytenoid and Cricothyroid Activations to Postural and Acoustic Features in a Fiber-Gel Model of the Vocal Folds
by Anil Palaparthi, Simeon Smith and Ingo R. Titze
Appl. Sci. 2019, 9(21), 4671; https://doi.org/10.3390/app9214671 - 01 Nov 2019
Cited by 5 | Viewed by 2623
Abstract
Any specific vowel sound that humans produce can be represented in terms of four perceptual features in addition to the vowel category. They are pitch, loudness, brightness, and roughness. Corresponding acoustic features chosen here are fundamental frequency (fo), sound pressure [...] Read more.
Any specific vowel sound that humans produce can be represented in terms of four perceptual features in addition to the vowel category. They are pitch, loudness, brightness, and roughness. Corresponding acoustic features chosen here are fundamental frequency (fo), sound pressure level (SPL), normalized spectral centroid (NSC), and approximate entropy (ApEn). In this study, thyroarytenoid (TA) and cricothyroid (CT) activations were varied computationally to study their relationship with these four specific acoustic features. Additionally, postural and material property variables such as vocal fold length (L) and fiber stress ( σ ) in the three vocal fold tissue layers were also calculated. A fiber-gel finite element model developed at National Center for Voice and Speech was used for this purpose. Muscle activation plots were generated to obtain the dependency of postural and acoustic features on TA and CT muscle activations. These relationships were compared against data obtained from previous in vivo human larynx studies and from canine laryngeal studies. General trends are that fo and SPL increase with CT activation, while NSC decreases when CT activation is raised above 20%. With TA activation, acoustic features have no uniform trends, except SPL increases uniformly with TA if there is a co-variation with CT activation. Trends for postural variables and material properties are also discussed in terms of activation levels. Full article
(This article belongs to the Special Issue Computational Methods and Engineering Solutions to Voice)
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17 pages, 4427 KiB  
Article
Toward Development of a Vocal Fold Contact Pressure Probe: Bench-Top Validation of a Dual-Sensor Probe Using Excised Human Larynx Models
by Daryush D. Mehta, James B. Kobler, Steven M. Zeitels, Matías Zañartu, Byron D. Erath, Mohsen Motie-Shirazi, Sean D. Peterson, Robert H. Petrillo and Robert E. Hillman
Appl. Sci. 2019, 9(20), 4360; https://doi.org/10.3390/app9204360 - 16 Oct 2019
Cited by 10 | Viewed by 3429
Abstract
A critical element in understanding voice production mechanisms is the characterization of vocal fold collision, which is widely considered a primary etiological factor in the development of common phonotraumatic lesions such as nodules and polyps. This paper describes the development of a transoral, [...] Read more.
A critical element in understanding voice production mechanisms is the characterization of vocal fold collision, which is widely considered a primary etiological factor in the development of common phonotraumatic lesions such as nodules and polyps. This paper describes the development of a transoral, dual-sensor intraglottal/subglottal pressure probe for the simultaneous measurement of vocal fold collision and subglottal pressures during phonation using two miniature sensors positioned 7.6 mm apart at the distal end of a rigid cannula. Proof-of-concept testing was performed using excised whole-mount and hemilarynx human tissue aerodynamically driven into self-sustained oscillation, with systematic variation of the superior–inferior positioning of the vocal fold collision sensor. In the hemilarynx experiment, signals from the pressure sensors were synchronized with an acoustic microphone, a tracheal-surface accelerometer, and two high-speed video cameras recording at 4000 frames per second for top–down and en face imaging of the superior and medial vocal fold surfaces, respectively. As expected, the intraglottal pressure signal exhibited an impulse-like peak when vocal fold contact occurred, followed by a broader peak associated with intraglottal pressure build-up during the de-contacting phase. As subglottal pressure was increased, the peak amplitude of the collision pressure increased and typically reached a value below that of the average subglottal pressure. Results provide important baseline vocal fold collision pressure data with which computational models of voice production can be developed and in vivo measurements can be referenced. Full article
(This article belongs to the Special Issue Computational Methods and Engineering Solutions to Voice)
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27 pages, 7672 KiB  
Article
Acoustic Pressure Pipette Aspiration Method Combined with Finite Element Analysis for Isotropic Materials
by Mohammadali Maghzinajafabadi, Raphael Lamprecht, Marion Semmler and Alexander Sutor
Appl. Sci. 2019, 9(18), 3875; https://doi.org/10.3390/app9183875 - 15 Sep 2019
Cited by 3 | Viewed by 2580
Abstract
A measurement setup combined with a numerical simulation by a linear finite element analysis is presented as a method to determine the elastic modulus of both artificial and real tissue as a function of frequency. At the end, the future goal is to [...] Read more.
A measurement setup combined with a numerical simulation by a linear finite element analysis is presented as a method to determine the elastic modulus of both artificial and real tissue as a function of frequency. At the end, the future goal is to develop and validate the method to measure the elastic modulus of in-vivo human vocal folds over the human phonation frequency range. In the present study, a miniaturized acoustic pressure pipette aspiration technique is developed to measure the material characteristics of an isotropic silicone specimen with similar characteristics as human vocal folds. In previous studies, friction and compression force effects of the pipette tip wall on the surface of the sample and the radius of the pipette were not investigated. Moreover, the large scale of the measurement setups made them impossible to use for clinical applications. Therefore, two different pipette sample cross-section boundary conditions and two different pipette radii were used. With the aim of ensuring reliable results, we tested our method with pipettes of two different radii on four silicone samples with different consistencies over a frequency range of 50–500 Hz. The simulation verified the measurement results in which the strong dependency of the elastic modulus on the excitation frequency, radius of the pipette, the pipette tip compression force and friction was revealed. By the simulation results, two different frequency dependent equations were developed for calculating elastic modulus of the silicone mixtures in the two cross-section boundary conditions. It was concluded that using a very small gap in between the pipette tip and the specimen can cancel the impact of the pipette tip force and friction which are the major cause of uncertainty. However, if a connection between the pipette and the surface is unpreventable, the contact force should be restricted to be absolutely zero. Full article
(This article belongs to the Special Issue Computational Methods and Engineering Solutions to Voice)
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17 pages, 1210 KiB  
Article
Acoustic and Aerodynamic Coupling during Phonation in MRI-Based Vocal Tract Replicas
by Judith Probst, Alexander Lodermeyer, Sahar Fattoum, Stefan Becker, Matthias Echternach, Bernhard Richter, Michael Döllinger and Stefan Kniesburges
Appl. Sci. 2019, 9(17), 3562; https://doi.org/10.3390/app9173562 - 30 Aug 2019
Cited by 5 | Viewed by 3021
Abstract
Voiced speech is the result of a fluid-structure-acoustic interaction in larynx and vocal tract (VT). Previous studies show a strong influence of the VT on this interaction process, but are limited to individually obtained VT geometries. In order to overcome this restriction and [...] Read more.
Voiced speech is the result of a fluid-structure-acoustic interaction in larynx and vocal tract (VT). Previous studies show a strong influence of the VT on this interaction process, but are limited to individually obtained VT geometries. In order to overcome this restriction and to provide a more general VT replica, we computed a simplified, averaged VT geometry for the vowel /a/. The basis for that were MRI-derived cross-sections along the straightened VT centerline of six professional tenors. The resulting mean VT replica, as well as realistic and simplified VT replicas of each tenor were 3D-printed for experiments with silicone vocal folds that show flow-induced oscillations. Our results reveal that all replicas, including the mean VT, reproduce the characteristic formants with mean deviations of 12% when compared with the subjects’ audio recordings. The overall formant structure neither is impaired by the averaging process, nor by the simplified geometry. Nonetheless, alterations in the broadband, non-harmonic portions of the sound spectrum indicate changed aerodynamic characteristics within the simplified VT. In conclusion, our mean VT replica shows similar formant properties as found in vivo. This indicates that the mean VT geometry is suitable for further investigations of the fluid-structure-acoustic interaction during phonation. Full article
(This article belongs to the Special Issue Computational Methods and Engineering Solutions to Voice)
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22 pages, 3153 KiB  
Article
Toward Development of a Vocal Fold Contact Pressure Probe: Sensor Characterization and Validation Using Synthetic Vocal Fold Models
by Mohsen Motie-Shirazi, Matías Zañartu, Sean D. Peterson, Daryush D. Mehta, James B. Kobler, Robert E. Hillman and Byron D. Erath
Appl. Sci. 2019, 9(15), 3002; https://doi.org/10.3390/app9153002 - 26 Jul 2019
Cited by 22 | Viewed by 3694
Abstract
Excessive vocal fold collision pressures during phonation are considered to play a primary role in the formation of benign vocal fold lesions, such as nodules. The ability to accurately and reliably acquire intraglottal pressure has the potential to provide unique insights into the [...] Read more.
Excessive vocal fold collision pressures during phonation are considered to play a primary role in the formation of benign vocal fold lesions, such as nodules. The ability to accurately and reliably acquire intraglottal pressure has the potential to provide unique insights into the pathophysiology of phonotrauma. Difficulties arise, however, in directly measuring vocal fold contact pressures due to physical intrusion from the sensor that may disrupt the contact mechanics, as well as difficulty in determining probe/sensor position relative to the contact location. These issues are quantified and addressed through the implementation of a novel approach for identifying the timing and location of vocal fold contact, and measuring intraglottal and vocal fold contact pressures via a pressure probe embedded in the wall of a hemi-laryngeal flow facility. The accuracy and sensitivity of the pressure measurements are validated against ground truth values. Application to in vivo approaches are assessed by acquiring intraglottal and VF contact pressures using a synthetic, self-oscillating vocal fold model in a hemi-laryngeal configuration, where the sensitivity of the measured intraglottal and vocal fold contact pressure relative to the sensor position is explored. Full article
(This article belongs to the Special Issue Computational Methods and Engineering Solutions to Voice)
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24 pages, 2411 KiB  
Article
Towards a Physiological Scale of Vocal Fold Agent-Based Models of Surgical Injury and Repair: Sensitivity Analysis, Calibration and Verification
by Aman Garg, Samson Yuen, Nuttiiya Seekhao, Grace Yu, Jeannie A. C. Karwowski, Michael Powell, Jon T. Sakata, Luc Mongeau, Joseph JaJa and Nicole Y. K. Li-Jessen
Appl. Sci. 2019, 9(15), 2974; https://doi.org/10.3390/app9152974 - 25 Jul 2019
Cited by 11 | Viewed by 2702
Abstract
Agent based models (ABM) were developed to numerically simulate the biological response to surgical vocal fold injury and repair at the physiological level. This study aimed to improve the representation of existing ABM through a combination of empirical and computational experiments. Empirical data [...] Read more.
Agent based models (ABM) were developed to numerically simulate the biological response to surgical vocal fold injury and repair at the physiological level. This study aimed to improve the representation of existing ABM through a combination of empirical and computational experiments. Empirical data of vocal fold cell populations including neutrophils, macrophages and fibroblasts were obtained using flow cytometry up to four weeks following surgical injury. Random Forests were used as a sensitivity analysis method to identify model parameters that were most influential to ABM outputs. Statistical Parameter Optimization Tool for Python was used to calibrate those parameter values to match the ABM-simulation data with the corresponding empirical data from Day 1 to Day 5 following surgery. Model performance was evaluated by verifying if the empirical data fell within the 95% confidence intervals of ABM outputs of cell quantities at Day 7, Week 2 and Week 4. For Day 7, all empirical data were within the ABM output ranges. The trends of ABM-simulated cell populations were also qualitatively comparable to those of the empirical data beyond Day 7. Exact values, however, fell outside of the 95% statistical confidence intervals. Parameters related to fibroblast proliferation were indicative to the ABM-simulation of fibroblast dynamics in final stages of wound healing. Full article
(This article belongs to the Special Issue Computational Methods and Engineering Solutions to Voice)
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15 pages, 3503 KiB  
Article
Geometry of the Vocal Tract and Properties of Phonation near Threshold: Calculations and Measurements
by Lewis Fulcher, Alexander Lodermeyer, George Kähler, Stefan Becker and Stefan Kniesburges
Appl. Sci. 2019, 9(13), 2755; https://doi.org/10.3390/app9132755 - 08 Jul 2019
Cited by 7 | Viewed by 3344
Abstract
In voice research, analytically-based models are efficient tools to investigate the basic physical mechanisms of phonation. Calculations based on lumped element models describe the effects of the air in the vocal tract upon threshold pressure (Pth) by its inertance. The [...] Read more.
In voice research, analytically-based models are efficient tools to investigate the basic physical mechanisms of phonation. Calculations based on lumped element models describe the effects of the air in the vocal tract upon threshold pressure (Pth) by its inertance. The latter depends on the geometrical boundary conditions prescribed by the vocal tract length (directly) and its cross-sectional area (inversely). Using Titze’s surface wave model (SWM) to account for the properties of the vocal folds, the influence of the vocal tract inertia is examined by two sets of calculations in combination with experiments that apply silicone-based vocal folds. In the first set, a vocal tract is constructed whose cross-sectional area is adjustable from 2.7 cm2 to 11.7 cm2. In the second set, the length of the vocal tract is varied from 4.0 cm to 59.0 cm. For both sets, the pressure and frequency data are collected and compared with calculations based on the SWM. In most cases, the measurements support the calculations; hence, the model is suited to describe and predict basic mechanisms of phonation and the inertial effects caused by a vocal tract. Full article
(This article belongs to the Special Issue Computational Methods and Engineering Solutions to Voice)
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20 pages, 3074 KiB  
Article
Bayesian Inference of Vocal Fold Material Properties from Glottal Area Waveforms Using a 2D Finite Element Model
by Paul J. Hadwin, Mohsen Motie-Shirazi, Byron D. Erath and Sean D. Peterson
Appl. Sci. 2019, 9(13), 2735; https://doi.org/10.3390/app9132735 - 06 Jul 2019
Cited by 14 | Viewed by 3132
Abstract
Bayesian estimation has been previously demonstrated as a viable method for developing subject-specific vocal fold models from observations of the glottal area waveform. These prior efforts, however, have been restricted to lumped-element fitting models and synthetic observation data. The indirect relationship between the [...] Read more.
Bayesian estimation has been previously demonstrated as a viable method for developing subject-specific vocal fold models from observations of the glottal area waveform. These prior efforts, however, have been restricted to lumped-element fitting models and synthetic observation data. The indirect relationship between the lumped-element parameters and physical tissue properties renders extracting the latter from the former difficult. Herein we propose a finite element fitting model, which treats the vocal folds as a viscoelastic deformable body comprised of three layers. Using the glottal area waveforms generated by self-oscillating silicone vocal folds we directly estimate the elastic moduli, density, and other material properties of the silicone folds using a Bayesian importance sampling approach. Estimated material properties agree with the “ground truth” experimental values to within 3 % for most parameters. By considering cases with varying subglottal pressure and medial compression we demonstrate that the finite element model coupled with Bayesian estimation is sufficiently sensitive to distinguish between experimental configurations. Additional information not available experimentally, namely, contact pressures, are extracted from the developed finite element models. The contact pressures are found to increase with medial compression and subglottal pressure, in agreement with expectation. Full article
(This article belongs to the Special Issue Computational Methods and Engineering Solutions to Voice)
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16 pages, 8629 KiB  
Article
Imaging the Vocal Folds: A Feasibility Study on Strain Imaging and Elastography of Porcine Vocal Folds
by Raphael Lamprecht, Mohammadali Maghzinajafabadi, Marion Semmler and Alexander Sutor
Appl. Sci. 2019, 9(13), 2729; https://doi.org/10.3390/app9132729 - 05 Jul 2019
Cited by 8 | Viewed by 4260
Abstract
Vocal folds are an essential part of human voice production. The biomechanical properties are a good indicator for pathological changes. In particular, as an oscillation system, changes in the biomechanical properties have an impact on the vibration behavior. Subsequently, those changes could lead [...] Read more.
Vocal folds are an essential part of human voice production. The biomechanical properties are a good indicator for pathological changes. In particular, as an oscillation system, changes in the biomechanical properties have an impact on the vibration behavior. Subsequently, those changes could lead to voice-related disturbances. However, no existing examination combines biomechanical properties and spatial imaging. Therefore, we propose an image registration-based approach, using ultrasound in order to gain this information synchronously. We used a quasi-static load to compress the tissue and measured the displacement by image registration. The strain distribution was directly calculated from the displacement field, whereas the elastic properties were estimated by a finite element model. In order to show the feasibility and reliability of the algorithm, we tested it on gelatin phantoms. Further, by examining ex vivo porcine vocal folds, we were able to show the practicability of the approach. We displayed the strain distribution in the tissue and the elastic properties of the vocal folds. The results were superimposed on the corresponding ultrasound images. The findings are promising and show the feasibility of the suggested approach. Possible applications are in improved diagnosis of voice disorders, by measuring the biomechanical properties of the vocal folds with ultrasound. The transducer will be placed on the vocal folds of the anesthetized patient, and the elastic properties will be measured. Further, the understanding of the vocal folds’ biomechanics and the voice forming process could benefit from it. Full article
(This article belongs to the Special Issue Computational Methods and Engineering Solutions to Voice)
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12 pages, 911 KiB  
Article
A Case of Specificity: How Does the Acoustic Voice Quality Index Perform in Normophonic Subjects?
by Christina Batthyany, Youri Maryn, Ilse Trauwaen, Els Caelenberghe, Joost van Dinther, Andrzej Zarowski and Floris Wuyts
Appl. Sci. 2019, 9(12), 2527; https://doi.org/10.3390/app9122527 - 21 Jun 2019
Cited by 26 | Viewed by 4012
Abstract
The acoustic voice quality index (AVQI) is a multiparametric tool based on six acoustic measurements to quantify overall voice quality in an objective manner, with the smoothed version of the cepstral peak prominence (CPPS) as its main contributor. In the last decade, many [...] Read more.
The acoustic voice quality index (AVQI) is a multiparametric tool based on six acoustic measurements to quantify overall voice quality in an objective manner, with the smoothed version of the cepstral peak prominence (CPPS) as its main contributor. In the last decade, many studies demonstrated its robust diagnostic accuracy and high sensitivity to voice changes across voice therapy in different languages. The aim of the present study was to provide information regarding AVQI’s and CPPS’s performance in normophonic non-treatment-seeking subjects, since these data are still scarce; concatenated voice samples, consisting of sustained vowel phonation and continuous speech, from 123 subjects (72 females, 51 males; between 20 and 60 years old) without vocally relevant complaints were evaluated by three raters and run in AVQI v.02.06. According to this auditory-perceptual evaluation, two cohorts were set up (normophonia versus slight perceived dysphonia). First, gender effects were investigated. Secondly, between-cohort differences in AVQI and CPPS were investigated. Thirdly, with the number of judges giving G = 1 to partition three sub-levels of slight hoarseness as an independent factor, differences in AVQI and CPPS across these sub-levels were investigated; for AVQI, no significant gender effect was found, whereas, for CPPS, significant trends were observed. For both AVQI and CPPS, no significant differences were found between normophonic and slightly dysphonic subjects. For AVQI, however, this difference did approach significance; these findings emphasize the need for a normative study with a greater sample size and subsequently greater statistical power to detect possible significant effects and differences. Full article
(This article belongs to the Special Issue Computational Methods and Engineering Solutions to Voice)
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21 pages, 1246 KiB  
Article
Estimating Vocal Fold Contact Pressure from Raw Laryngeal High-Speed Videoendoscopy Using a Hertz Contact Model
by Manuel E. Díaz-Cádiz, Sean D. Peterson, Gabriel E. Galindo, Víctor M. Espinoza, Mohsen Motie-Shirazi, Byron D. Erath and Matías Zañartu
Appl. Sci. 2019, 9(11), 2384; https://doi.org/10.3390/app9112384 - 11 Jun 2019
Cited by 11 | Viewed by 5104
Abstract
The development of trauma-induced lesions of the vocal folds (VFs) has been linked to a high collision pressure on the VF surface. However, there are no direct methods for the clinical assessment of VF collision, thus limiting the objective assessment of these disorders. [...] Read more.
The development of trauma-induced lesions of the vocal folds (VFs) has been linked to a high collision pressure on the VF surface. However, there are no direct methods for the clinical assessment of VF collision, thus limiting the objective assessment of these disorders. In this study, we develop a video processing technique to directly quantify the mechanical impact of the VFs using solely laryngeal kinematic data. The technique is based on an edge tracking framework that estimates the kinematic sequence of each VF edge with a Kalman filter approach and a Hertzian impact model to predict the contact force during the collision. The proposed formulation overcomes several limitations of prior efforts since it uses a more relevant VF contact geometry, it does not require calibrated physical dimensions, it is normalized by the tissue properties, and it applies a correction factor for using a superior view only. The proposed approach is validated against numerical models, silicone vocal fold models, and prior studies. A case study with high-speed videoendoscopy recordings provides initial insights between the sound pressure level and contact pressure. Thus, the proposed method has a high potential in clinical practice and could also be adapted to operate with laryngeal stroboscopic systems. Full article
(This article belongs to the Special Issue Computational Methods and Engineering Solutions to Voice)
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19 pages, 14060 KiB  
Article
Towards a Clinically Applicable Computational Larynx Model
by Hossein Sadeghi, Stefan Kniesburges, Sebastian Falk, Manfred Kaltenbacher, Anne Schützenberger and Michael Döllinger
Appl. Sci. 2019, 9(11), 2288; https://doi.org/10.3390/app9112288 - 03 Jun 2019
Cited by 13 | Viewed by 3589
Abstract
The enormous computational power and time required for simulating the complex phonation process preclude the effective clinical use of computational larynx models. The aim of this study was to evaluate the potential of a numerical larynx model, considering the computational time and resources [...] Read more.
The enormous computational power and time required for simulating the complex phonation process preclude the effective clinical use of computational larynx models. The aim of this study was to evaluate the potential of a numerical larynx model, considering the computational time and resources required. Using Large Eddy Simulations (LES) in a 3D numerical larynx model with prescribed motion of vocal folds, the complicated fluid-structure interaction problem in phonation was reduced to a pure flow simulation with moving boundaries. The simulated laryngeal flow field is in good agreement with the experimental results obtained from authors’ synthetic larynx model. By systematically decreasing the spatial and temporal resolutions of the numerical model and optimizing the computational resources of the simulations, the elapsed simulation time was reduced by 90% to less than 70 h for 10 oscillation cycles of the vocal folds. The proposed computational larynx model with reduced mesh resolution is still able to capture the essential laryngeal flow characteristics and produce results with sufficiently good accuracy in a significant shorter time-to-solution. The reduction in computational time achieved is a promising step towards the clinical application of these computational larynx models in the near future. Full article
(This article belongs to the Special Issue Computational Methods and Engineering Solutions to Voice)
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18 pages, 3182 KiB  
Article
Impact of Subharmonic and Aperiodic Laryngeal Dynamics on the Phonatory Process Analyzed in Ex Vivo Rabbit Models
by Fabian Thornton, Michael Döllinger, Stefan Kniesburges, David Berry, Christoph Alexiou and Anne Schützenberger
Appl. Sci. 2019, 9(9), 1963; https://doi.org/10.3390/app9091963 - 13 May 2019
Cited by 8 | Viewed by 6941
Abstract
Normal voice is characterized by periodic oscillations of the vocal folds. On the other hand, disordered voice dynamics (e.g., subharmonic and aperiodic oscillations) are often associated with voice pathologies and dysphonia. Unfortunately, not all investigations may be conducted on human subjects; hence animal [...] Read more.
Normal voice is characterized by periodic oscillations of the vocal folds. On the other hand, disordered voice dynamics (e.g., subharmonic and aperiodic oscillations) are often associated with voice pathologies and dysphonia. Unfortunately, not all investigations may be conducted on human subjects; hence animal laryngeal studies have been performed for many years to better understand human phonation. The rabbit larynx has been shown to be a potential model of the human larynx. Despite this fact, only a few studies regarding the phonatory parameters of rabbit larynges have been performed. Further, to the best of our knowledge, no ex vivo study has systematically investigated phonatory parameters from high-speed, audio and subglottal pressure data with irregular oscillations. To remedy this, the present study analyzes experiments with sustained phonation in 11 ex vivo rabbit larynges for 51 conditions of disordered vocal fold dynamics. (1) The results of this study support previous findings on non-disordered data, that the stronger the glottal closure insufficiency is during phonation, the worse the phonatory characteristics are; (2) aperiodic oscillations showed worse phonatory results than subharmonic oscillations; (3) in the presence of both types of irregular vibrations, the voice quality (i.e., cepstral peak prominence) of the audio and subglottal signal greatly deteriorated compared to normal/periodic vibrations. In summary, our results suggest that the presence of both types of irregular vibration have a major impact on voice quality and should be considered along with glottal closure measures in medical diagnosis and treatment. Full article
(This article belongs to the Special Issue Computational Methods and Engineering Solutions to Voice)
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18 pages, 3944 KiB  
Article
Discrimination between Modal, Breathy and Pressed Voice for Single Vowels Using Neck-Surface Vibration Signals
by Zhengdong Lei, Evan Kennedy, Laura Fasanella, Nicole Yee-Key Li-Jessen and Luc Mongeau
Appl. Sci. 2019, 9(7), 1505; https://doi.org/10.3390/app9071505 - 11 Apr 2019
Cited by 11 | Viewed by 3961
Abstract
The purpose of this study was to investigate the feasibility of using neck-surface acceleration signals to discriminate between modal, breathy and pressed voice. Voice data for five English single vowels were collected from 31 female native Canadian English speakers using a portable Neck [...] Read more.
The purpose of this study was to investigate the feasibility of using neck-surface acceleration signals to discriminate between modal, breathy and pressed voice. Voice data for five English single vowels were collected from 31 female native Canadian English speakers using a portable Neck Surface Accelerometer (NSA) and a condenser microphone. Firstly, auditory-perceptual ratings were conducted by five clinically-certificated Speech Language Pathologists (SLPs) to categorize voice type using the audio recordings. Intra- and inter-rater analyses were used to determine the SLPs’ reliability for the perceptual categorization task. Mixed-type samples were screened out, and congruent samples were kept for the subsequent classification task. Secondly, features such as spectral harmonics, jitter, shimmer and spectral entropy were extracted from the NSA data. Supervised learning algorithms were used to map feature vectors to voice type categories. A feature wrapper strategy was used to evaluate the contribution of each feature or feature combinations to the classification between different voice types. The results showed that the highest classification accuracy on a full set was 82.5%. The breathy voice classification accuracy was notably greater (approximately 12%) than those of the other two voice types. Shimmer and spectral entropy were the best correlated metrics for the classification accuracy. Full article
(This article belongs to the Special Issue Computational Methods and Engineering Solutions to Voice)
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17 pages, 5006 KiB  
Article
Influence of Analyzed Sequence Length on Parameters in Laryngeal High-Speed Videoendoscopy
by Patrick Schlegel, Marion Semmler, Melda Kunduk, Michael Döllinger, Christopher Bohr and Anne Schützenberger
Appl. Sci. 2018, 8(12), 2666; https://doi.org/10.3390/app8122666 - 18 Dec 2018
Cited by 22 | Viewed by 4558
Abstract
Laryngeal high-speed videoendoscopy (HSV) allows objective quantification of vocal fold vibratory characteristics. However, it is unknown how the analyzed sequence length affects some of the computed parameters. To examine if varying sequence lengths influence parameter calculation, 20 HSV recordings of healthy females during [...] Read more.
Laryngeal high-speed videoendoscopy (HSV) allows objective quantification of vocal fold vibratory characteristics. However, it is unknown how the analyzed sequence length affects some of the computed parameters. To examine if varying sequence lengths influence parameter calculation, 20 HSV recordings of healthy females during sustained phonation were investigated. The clinical prevalent Photron Fastcam MC2 camera with a frame rate of 4000 fps and a spatial resolution of 512 × 256 pixels was used to collect HSV data. The glottal area waveform (GAW), describing the increase and decrease of the area between the vocal folds during phonation, was extracted. Based on the GAW, 16 perturbation parameters were computed for sequences of 5, 10, 20, 50 and 100 consecutive cycles. Statistical analysis was performed using SPSS Statistics, version 21. Only three parameters (18.8%) were statistically significantly influenced by changing sequence lengths. Of these parameters, one changed until 10 cycles were reached, one until 20 cycles were reached and one, namely Amplitude Variability Index (AVI), changed between almost all groups of different sequence lengths. Moreover, visually observable, but not statistically significant, changes within parameters were observed. These changes were often most prominent between shorter sequence lengths. Hence, we suggest using a minimum sequence length of at least 20 cycles and discarding the parameter AVI. Full article
(This article belongs to the Special Issue Computational Methods and Engineering Solutions to Voice)
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