An extended two-dimensional vocal tract model for fast acoustic simulation of single-axis symmetric three-dimensional tubes

The simulation of two-dimensional (2D) wave propagation is an affordable computational task and its use can potentially improve time performance in vocal tracts' acoustic analysis. Several models have been designed that rely on 2D wave solvers and include 2D representations of three-dimensional (3D) vocal tract-like geometries. However, until now, only the acoustics of straight 3D tubes with circular cross-sections have been successfully replicated with this approach. Furthermore, the simulation of the resulting 2D shapes requires extremely high spatio-temporal resolutions, dramatically reducing the speed boost deriving from the usage of a 2D wave solver. In this paper, we introduce an in-progress novel vocal tract model that extends the 2D Finite-Difference Time-Domain wave solver (2.5D FDTD) by adding tube depth, derived from the area functions, to the acoustic solver. The model combines the speed of a light 2D numerical scheme with the ability to natively simulate 3D tubes that are symmetric in one dimension, hence relaxing previous resolution requirements. An implementation of the 2.5D FDTD is presented, along with evaluation of its performance in the case of static vowel modeling. The paper discusses the current features and limits of the approach, and the potential impact on computational acoustics applications.Comment: 5 pages, 2 figures, Interspeech 2019 submissio

Modelling Physical Mechanisms of Nodule Development in Phonotraumatic Vocal Hyperfunction using Computational Vocal Fold Models

Vocal hyperfunction is a prevalent voice disorder with significant impacts on the daily lives of patients, but has poorly understood causes. At its root, vocal hyperfunction is neurological, involving excessive muscular activation due to compensation for some underlying issue. In order to improve understanding of the causes of this disorder and ultimately improve its treatment, this thesis uses computational models to investigate mechanical aspects in the development of vocal fold nodules in phonotraumatic vocal hyperfunction (a specific class of vocal hyperfunction), specifically: whether biomechanical differences in stiffness of the vocal folds can lead to inefficient speech production that predisposes one to developing these nodule, and whether swelling can establish an amplifying feedback loop, a so-called "vicious cycle", wherein swelling leads to compensatory adjustments that incur further swelling and ultimately lead to nodule. To address these questions a two-dimensional finite-element vocal fold model coupled with a simplified one-dimensional flow model was developed with modifications to this basic model made to study the phenomena of interest. Towards modelling swelling, a computationally efficient approach to model the epithelium layer of the vocal folds is also developed and validated. To investigate the first research question, the aforementioned model was adapted to study phonation onset pressure, a measure of effort required to produce speech, as a function of vocal fold stiffness. The results show that onset pressure is primarily dependent on just three stiffness distributions: smooth distributions with body-cover stiffness differences and smooth distributions with inferior-superior stiffness differences minimize onset pressure while a uniform stiffness increase increases onset pressure. Since a uniform stiffness increase increases the natural frequency of the vocal folds, this increase in onset pressure is roughly associated with increases in frequency. This suggests that for a given average stiffness (onset frequency) deviations from an optimal body-cover and inferior-superior-like distribution lead to increases in phonatory effort that could increase susceptibility to vocal hyperfunction. To investigate the second research question, the finite element model was augmented with a model of swelling, as well as an epithelium using a membrane model. Results showed that swelling has negligible impact on loudness of speech but significantly influences frequency, and that furthermore, swelling increases measures of phonotrauma. These results suggest that swelling could incur a vicious cycle. Specifically, a decrease in fundamental frequency initiates compensatory adjustments through increased muscle tension and subglottal pressure, which tends to increase phonotrauma in the folds, and increased swelling with phonotrauma does not tend to limit further swelling. This result demonstrates how swelling can potentially lead to the formation of nodule

7th International Conference on Nonlinear Vibrations, Localization and Energy Transfer: Extended Abstracts

International audienceThe purpose of our conference is more than ever to promote exchange and discussions between scientists from all around the world about the latest research developments in the area of nonlinear vibrations, with a particular emphasis on the concept of nonlinear normal modes and targeted energytransfer

Models and Analysis of Vocal Emissions for Biomedical Applications

The Models and Analysis of Vocal Emissions with Biomedical Applications (MAVEBA) workshop came into being in 1999 from the particularly felt need of sharing know-how, objectives and results between areas that until then seemed quite distinct such as bioengineering, medicine and singing. MAVEBA deals with all aspects concerning the study of the human voice with applications ranging from the neonate to the adult and elderly. Over the years the initial issues have grown and spread also in other aspects of research such as occupational voice disorders, neurology, rehabilitation, image and video analysis. MAVEBA takes place every two years always in Firenze, Italy

Vocal fold vibratory and acoustic features in fatigued Karaoke singers

Session 3aMU - Musical Acoustics and Speech Communication: Singing Voice in Asian CulturesKaraoke is a popular singing entertainment particularly in Asia and is gaining more popularity in the rest of world. In Karaoke, an amateur singer sings with the background music and video (usually guided by the lyric captions on the video screen) played by Karaoke machine, using a microphone and an amplification system. As the Karaoke singers usually have no formal training, they may be more vulnerable to vocal fatigue as they may overuse and/or misuse their voices in the intensive and extensive singing activities. It is unclear whether vocal fatigue is accompanied by any vibration pattern or physiological changes of vocal folds. In this study, 20 participants aged from 18 to 23 years with normal voice were recruited to participate in an prolonged singing task, which induced vocal fatigue. High speed laryngscopic imaging and acoustic signals were recorded before and after the singing task. Images of /i/ phonation were quantitatively analyzed using the High Speed Video Processing (HSVP) program (Yiu, et al. 2010). It was found that the glottis became relatively narrower following fatigue, while the acoustic signals were not sensitive to measure change following fatigue. © 2012 Acoustical Society of Americapublished_or_final_versio

SOLID-SHELL FINITE ELEMENT MODELS FOR EXPLICIT SIMULATIONS OF CRACK PROPAGATION IN THIN STRUCTURES

Crack propagation in thin shell structures due to cutting is conveniently simulated using explicit finite element approaches, in view of the high nonlinearity of the problem. Solidshell elements are usually preferred for the discretization in the presence of complex material behavior and degradation phenomena such as delamination, since they allow for a correct representation of the thickness geometry. However, in solid-shell elements the small thickness leads to a very high maximum eigenfrequency, which imply very small stable time-steps. A new selective mass scaling technique is proposed to increase the time-step size without affecting accuracy. New ”directional” cohesive interface elements are used in conjunction with selective mass scaling to account for the interaction with a sharp blade in cutting processes of thin ductile shells

Advances in Vibration Analysis Research

Vibrations are extremely important in all areas of human activities, for all sciences, technologies and industrial applications. Sometimes these Vibrations are useful but other times they are undesirable. In any case, understanding and analysis of vibrations are crucial. This book reports on the state of the art research and development findings on this very broad matter through 22 original and innovative research studies exhibiting various investigation directions. The present book is a result of contributions of experts from international scientific community working in different aspects of vibration analysis. The text is addressed not only to researchers, but also to professional engineers, students and other experts in a variety of disciplines, both academic and industrial seeking to gain a better understanding of what has been done in the field recently, and what kind of open problems are in this area