Department of Head and Neck Surgery, UCLA School of Medicine, 31-24 Rehabilitation Center, 1000 Veteran Avenue, Los Angeles, California 90095-1794, USA.
J Acoust Soc Am. 2013 May;133(5):2972-83. doi: 10.1121/1.4799809.
The influence of the thyroarytenoid (TA) and cricothyroid (CT) muscle activation on vocal fold stiffness and eigenfrequencies was investigated in a muscularly controlled continuum model of the vocal folds. Unlike the general understanding that vocal fold fundamental frequency was determined by vocal fold tension, this study showed that vocal fold eigenfrequencies were primarily determined by vocal fold stiffness. This study further showed that, with reference to the resting state of zero strain, vocal fold stiffness in both body and cover layers increased with either vocal fold elongation or shortening. As a result, whether vocal fold eigenfrequencies increased or decreased with CT/TA activation depended on how the CT/TA interaction influenced vocal fold deformation. For conditions of strong CT activation and thus an elongated vocal fold, increasing TA contraction reduced the degree of vocal fold elongation and thus reduced vocal fold eigenfrequencies. For conditions of no CT activation and thus a resting or slightly shortened vocal fold, increasing TA contraction increased the degree of vocal fold shortening and thus increased vocal fold eigenfrequencies. In the transition region of a slightly elongated vocal fold, increasing TA contraction first decreased and then increased vocal fold eigenfrequencies.
本研究通过对声带的肌肉控制连续体模型，调查了杓状软骨肌（TA）和环甲肌（CT）的激活对声带僵硬和本征频率的影响。与声带基频由声带张力决定的普遍认识不同，本研究表明，声带本征频率主要由声带僵硬度决定。本研究进一步表明，相对于零应变的静止状态，无论是在声带体长增加还是缩短的情况下，声带体层和盖层的声带僵硬度均会增加。因此，CT/TA 激活对声带本征频率的影响取决于 CT/TA 相互作用如何影响声带变形。对于 CT 强烈激活且声带伸长的情况，增加 TA 收缩会减少声带伸长的程度，从而降低声带本征频率。对于无 CT 激活且声带处于静止或稍短的情况，增加 TA 收缩会增加声带缩短的程度，从而增加声带本征频率。在声带稍伸长的过渡区域，增加 TA 收缩会先降低然后增加声带本征频率。
