Department of Mechanical Engineering, University of Maine, Orono, Maine 04469, USA.
J Acoust Soc Am. 2019 Jul;146(1):369. doi: 10.1121/1.5116567.
The influence of vocal fold cover layer thickness on the flow-induced vibration and voice production was studied by using a continuum-mechanics based computational model. The cover-body thickness ratio of a three-layer vocal fold was systematically varied. The effect on the vocal fold stiffness, eigenfrequencies and eigenmodes, fundamental frequencies, glottal flow rate, vocal fold vibratory dynamics, and synchronization of the eigenmodes were analyzed by using the structure eigen analysis and flow-structure interaction simulations. It was found that the cover-body layer thickness ratio significantly affected the strength and synchronization of the eigenmodes during flow-structure interactions, and ultimately affected the fundamental frequency and vibration pattern. With the increasing cover-body thickness ratio, the strength of the wave-type higher-eigenfrequency modes increased, and that resulted in a nonlinear bifurcation of the system in which the system evolved from a regular periodic vibration to a periodic doubling vibration and then back to a regular periodic vibration with increased fundamental frequencies. During the transition, the system vibrated chaotically. Because of the increased strength of the wave-type modes, the maximum divergent angle of the glottis was also increased with the increasing cover-body thickness ratio.
采用基于连续介质力学的计算模型研究了声带覆盖层厚度对流致振动和发声的影响。系统地改变了三层声带的覆盖体厚度比。通过结构特征分析和流固耦合模拟,分析了声带刚度、本征频率和本征模态、基频、声门射流率、声带振动动力学以及本征模态同步对声带的影响。结果表明,覆盖体层厚度比对流固相互作用过程中本征模态的强度和同步性有显著影响,最终影响基频和振动模式。随着覆盖体厚度比的增加,波型高本征频率模态的强度增加,导致系统发生非线性分岔,系统从规则周期振动演变为倍周期振动,然后随着基频的增加恢复为规则周期振动。在过渡过程中,系统呈现混沌振动。由于波型模态的强度增加,最大声门射流发散角也随着覆盖体厚度比的增加而增加。