Ajuste fino de un modelo de producción vocal para estimar el estrés de impacto utilizando un método metaheurístico

Introducción: En modelos de producción vocal que emplean estructuras de resorte-masa-amortiguador, la precisión en la determinación de coeficientes de amortiguamiento que se asemejen a las características fisiológicas de las cuerdas vocales es crucial, teniendo en cuenta posibles variaciones en la representación de la viscoelasticidad. Objetivo: Este estudio tiene como objetivo realizar un ajuste paramétrico de un modelo de producción vocal basado en un sistema de resorte-masa-amortiguador que incorpora interacción con la presión subglótica, con el fin de modelar de manera precisa las fuerzas de colisión ejercidas por las cuerdas vocales durante la fonación. Método: Se utilizó un algoritmo de búsqueda metaheurística para la síntesis paramétrica. El algoritmo se aplicó a los coeficientes de elasticidad c1 y c2, así como a los coeficientes de amortiguamiento ε1 y ε2, que se correlacionan directamente con las matrices de masa del modelo. Esto facilita el ajuste de la composición de las cuerdas para lograr un comportamiento fisiológico deseado. Resultados: El comportamiento del sistema vocal para cada ciclo de simulación se comparó con un estándar predefinido en condiciones normales. El algoritmo determinó el punto final de la simulación evaluando las discrepancias entre características clave de las señales obtenidas y las deseadas. Conclusión: El ajuste paramétrico permitió la aproximación del comportamiento fisiológico de la producción vocal, proporcionando estimaciones de las fuerzas de impacto experimentadas por las cuerdas vocales durante la fonación.

Introduction: In vocal production models employing spring-mass-damper frameworks, precision in determining damping coefficients that align with physiological vocal fold characteristics is crucial, accounting for potential variations in the representation of viscosity-elasticity properties. Objective: This study aims to conduct a parametric fitting of a vocal production model based on a mass-spring-damper system incorporating subglottic pressure interaction, with the purpose of accurately modeling the collision forces exerted by vocal folds during phonation. Method: A metaheuristic search algorithm was employed for parametric synthesis. The algorithm was applied to elasticity coefficients c1 and c2, as well as damping coefficients ε1 and ε2, which directly correlate with the mass matrices of the model. This facilitates the adjustment of fold composition to achieve desired physiological behavior. Results: The vocal system's behavior for each simulation cycle was compared to a predefined standard under normal conditions. The algorithm determined the simulation endpoint by evaluating discrepancies between key features of the obtained signals and the desired ones. Conclusion: Parametric fitting enabled the approximation of physiological vocal production behavior, providing estimates of the impact forces experienced by vocal folds during phonation.

Biomechanical Models to Represent Vocal Physiology: A Systematic Review.

Biomechanical modeling allows obtaining information on physical phenomena that cannot be directly observed. This study aims to review models that represent voice production. A systematic review of the literature was conducted using PubMed/Medline, SCOPUS, and IEEE Xplore databases. To select the papers, we used the protocol PRISMA Statement. A total of 53 publications were included in this review. This article considers a taxonomic classification of models found in the literature. We propose four categories in the taxonomy: (1) Models representing the Source (Vocal folds); (2) Models representing the Filter (Vocal Tract); (3) Models representing the Source - Filter Interaction; and (4) Models representing the Airflow - Source Interaction. We include a bibliographic analysis with the evolution of the publications per category. We provide an analysis of the number as well of publications in journals per year. Moreover, we present an analysis of the term occurrence and its frequency of usage, as found in the literature. In each category, different types of vocal production models are mentioned and analyzed. The models account for the analysis of evidence about aerodynamic, biomechanical, and acoustic phenomena and their correlation with the physiological processes involved in the production of the human voice. This review gives an insight into the state of the art related to the mathematical modeling of voice production, analyzed from the viewpoint of vocal physiology.

Corn drying temperature, particle size, and amylase supplementation influence growth performance, digestive tract development, and nutrient utilization of broilers.

Broiler live performance may be influenced by postharvest corn drying temperature, and results could depend on particle size after grinding. The supplementation with an exogenous amylase may improve performance parameters, but responses to enzymes are also affected by particle size. Two parallel experiments were conducted to evaluate the effects of hard-kernel corn dried at 2 temperatures (35°C and 120°C), ground at 2 particle sizes (coarse or fine), and 3 supplementation levels (0, 133, and 266 g ton-1) of an exogenous amylase on live performance, gastrointestinal organ development, energy utilization, and nutrient digestibility. Twelve dietary treatments resulting from a 2 × 2 × 3 factorial arrangement of drying temperature, particle size, and amylase supplementation were evaluated in both experiments. A total of 1,920 day-old male chicks were randomly allocated to 96 floor pens, while 480 chicks were distributed among 4 battery brooder units. Ileal and fecal samples were collected to determine energy utilization and nutrient digestibility using titanium dioxide as inert marker. At 42 D, organs were collected, and relative weight or length was determined. Data were analyzed using a three-way ANOVA in a randomized complete block design. Feeding fine corn-based diets showed improvements on live performance for both studies. At 40 D, supplementing 266 g ton-1 of amylase improved feed conversion ratio (P < 0.05) by 1 point compared to chickens that consumed nonsupplemented diets and feed with amylase at 133 g ton-1. Broilers fed coarse corn-based diets had heavier gizzard (P < 0.001) and liver (P < 0.05) than chickens that consumed fine corn-based diets. In addition, starch digestibility was improved by amylase (P < 0.05) at 133 g ton-1 and by feeding coarse corn-based diets (P = 0.06). For chicks raised in cages (16 D), AMEn was increased (P < 0.01) by amylase supplementation regardless of its inclusion level. In conclusion, drying temperature and particle size interactions influenced broiler live performance, gastrointestinal organ development, nutrient digestibility, and energy utilization, and these parameters were improved by supplementing amylase.