Combining Multiobjective Optimization and Cluster Analysis to Study Vocal Fold Functional Morphology

Palaparthi, Anil; Riede, Tobias; Titze, Ingo R.

doi:10.1109/tbme.2014.2319194

Cited by 20 publications

(13 citation statements)

References 37 publications

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“…Such a comparison would entail thousands of simulation runs to fully cover the range of inputs. One approach to reduce the computational cost and to increase the efficiency of morphospace exploration is to combine a finite element model (FEM) voice simulation with multiobjective optimization [ 55 ]. This approach has been applied to vocal fold surgery simulation, in which the functional viabilities of two alternative vocal fold morphologies were demonstrated in silico [ 56 ].…”

Section: Resultsmentioning

confidence: 99%

Predicting Achievable Fundamental Frequency Ranges in Vocalization Across Species

2016

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Vocal folds are used as sound sources in various species, but it is unknown how vocal fold morphologies are optimized for different acoustic objectives. Here we identify two main variables affecting range of vocal fold vibration frequency, namely vocal fold elongation and tissue fiber stress. A simple vibrating string model is used to predict fundamental frequency ranges across species of different vocal fold sizes. While average fundamental frequency is predominantly determined by vocal fold length (larynx size), range of fundamental frequency is facilitated by (1) laryngeal muscles that control elongation and by (2) nonlinearity in tissue fiber tension. One adaptation that would increase fundamental frequency range is greater freedom in joint rotation or gliding of two cartilages (thyroid and cricoid), so that vocal fold length change is maximized. Alternatively, tissue layers can develop to bear a disproportionate fiber tension (i.e., a ligament with high density collagen fibers), increasing the fundamental frequency range and thereby vocal versatility. The range of fundamental frequency across species is thus not simply one-dimensional, but can be conceptualized as the dependent variable in a multi-dimensional morphospace. In humans, this could allow for variations that could be clinically important for voice therapy and vocal fold repair. Alternative solutions could also have importance in vocal training for singing and other highly-skilled vocalizations.

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Section: Resultsmentioning

confidence: 99%

Predicting Achievable Fundamental Frequency Ranges in Vocalization Across Species

2016

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“…Simulation has been used for planning medialization laryngoplasty, for example. The goal of this study is to assess the relative acoustic merits of subepithelial cordectomy and subligamental cordectomy utilizing a new computational approach combining finite element model (FEM) voice simulation with multiobjective optimization . A voice simulator produces one set of acoustic output variables, given a defined input vocal fold geometry and a fixed subglottal pressure.…”

Section: Introductionmentioning

confidence: 99%

“…The goal of this study is to assess the relative acoustic merits of subepithelial cordectomy and subligamental cordectomy utilizing a new computational approach combining finite element model (FEM) voice simulation 29 with multiobjective optimization. 30 A voice simulator produces one set of acoustic output variables, given a defined input vocal fold geometry and a fixed subglottal pressure. A meaningful comparison between two different vocal fold geometries should entail a range of possible acoustic outputs, given a clinically relevant range of subglottal pressures for each geometry.…”

Section: Introductionmentioning

confidence: 99%

“…To do this efficiently, a multiobjective optimization algorithm is coupled to the simulator to fully explore the range of possible acoustic outputs, an approach implemented in the National Center for Voice and Speech (NCVS) Phonosurgery Optimizer-Simulator. 30 In this study, the primary acoustic outcomes are the ranges of fundamental frequency (F 0 ) and sound pressure level (SPL). F 0 and SPL are of interest because they are fundamental acoustic parameters that characterize a voice.…”

Section: Introductionmentioning

confidence: 99%

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Effect of resection depth of early glottic cancer on vocal outcome: An optimized finite element simulation

et al. 2015

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Objectives/Hypothesis To test the hypothesis that subligamental cordectomy produces superior acoustic outcome than subepithelial cordectomy for early (T1-2) glottic cancer that requires complete removal of the superficial lamina propria but does not involve the vocal ligament. Study Design Computer simulation Methods A computational tool for vocal fold surgical planning and simulation (the National Center for Voice and Speech Phonosurgery Optimizer-Simulator) was used to evaluate the acoustic output of alternative vocal fold morphologies. Four morphologies were simulated: normal, subepithelial cordectomy, subligamental cordectomy, and transligamental cordectomy (partial ligament resection). The primary outcome measure was the range of fundamental frequency (F0) and sound pressure level (SPL). A more restricted F0-SPL range was considered less favorable because of reduced acoustic possibilities given the same range of driving subglottic pressure and identical vocal fold posturing. Results Subligamental cordectomy generated solutions covering an F0-SPL range 82% of normal for a rectangular vocal fold. In contrast, transligamental and subepithelial cordectomies produced significantly smaller F0-SPL ranges, 57% and 19% of normal, respectively. Conclusion This study illustrates the use of the Phonosurgery Optimizer-Simulator to test a specific hypothesis regarding the merits of two surgical alternatives. These simulation results provide theoretical support for vocal ligament excision with maximum muscle preservation when superficial lamina propria resection is necessary but the vocal ligament can be spared on oncological grounds. The resection of more tissue may paradoxically allow the eventual recovery of a better speaking voice, assuming glottal width is restored. Application of this conclusion to surgical practice will require confirmatory clinical data.

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“…A series of applications has derived from the Alipour et al (2000) finite element model, which we now call the fiber-gel finite element model (FG-FEM). Alipour and Scherer (2015) included the ventricular folds in self-sustained oscillation, Titze and Riede (2010) simulated the vocalization of Rocky Mountain elk, Palaparthi et al (2014) used the model to optimize functional vocal fold morphology, and Mau et al (2015) studied the effect of resection depth of early glottis cancer on vocal outcome computationally.…”

Section: Introductionmentioning

confidence: 99%

Comparison of a fiber-gel finite element model of vocal fold vibration to a transversely isotropic stiffness model

Titze¹,

Alipour²,

Blake³

et al. 2017

The Journal of the Acoustical Society of America

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A fiber-gel vocal fold model is compared to a transversely isotropic stiffness model in terms of normal mode vibration. The fiber-gel finite element model (FG-FEM) consists of a series of gel slices, each with a two-dimensional finite element mesh, in a plane transverse to the tissue fibers. The gel slices are coupled with fibers under tension in the anterior-posterior dimension. No vibrational displacement in the fiber-length direction is allowed, resulting in a plane strain state. This is consistent with the assumption of transverse displacement of a simple string, offering a wide range of natural frequencies (well into the kHz region) with variable tension. For low frequencies, the results compare favorably with the natural frequencies of a transversely isotropic elastic stiffness model (TISM) in which the shear modulus in the longitudinal plane is used to approximate the effect of fiber tension. For high frequencies, however, the natural frequencies do not approach the string mode frequencies unless plane strain is imposed on the TISM model. The simplifying assumption of plane strain, as well as the use of analytical closed-form shape functions, allow for substantial savings in computational time, which is important in clinical and exploratory applications of the FG-FEM model.

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Combining Multiobjective Optimization and Cluster Analysis to Study Vocal Fold Functional Morphology

Cited by 20 publications

References 37 publications

Predicting Achievable Fundamental Frequency Ranges in Vocalization Across Species

Predicting Achievable Fundamental Frequency Ranges in Vocalization Across Species

Effect of resection depth of early glottic cancer on vocal outcome: An optimized finite element simulation

Comparison of a fiber-gel finite element model of vocal fold vibration to a transversely isotropic stiffness model

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