Titze I R
Department of Speech Pathology and Audiology, University of Iowa.
J Speech Hear Res. 1991 Jun;34(3):460-72. doi: 10.1044/jshr.3403.460.
The time course of a force twitch in the thyroarytenoid muscle is modeled, and trains of twitches are summed to simulate force tetani. By incorporating means and standard deviations of motoneuron firing rates, and by applying random phase relationships between simulated motor units, a quantitative model of the ripple of vocal fold tension is obtained. From this ripple, perturbations in fundamental frequency are calculated as a function of the number of motor units in the muscle, the mean and standard deviation of the firing rate of dominant motoneurons, and the variability in the size (twitch amplitude) of the motor units. Predicted perturbations range between 0.2% and 1.2%, depending on the choice of parameters. Perturbation decreases with the number of motor units and with increased mean firing rate, but increases with the variability in motor unit size and with variability in the firing rate. Techniques are discussed by which neurologic jitter might be isolated from other sources of irregularity in vocal fold vibration.
对甲杓肌中一次力收缩的时间进程进行建模，并将一系列收缩进行累加以模拟强直收缩力。通过纳入运动神经元放电频率的均值和标准差，并应用模拟运动单位之间的随机相位关系，得到了声带张力波动的定量模型。根据该波动，计算出基频的扰动，其是肌肉中运动单位数量、优势运动神经元放电频率的均值和标准差以及运动单位大小（收缩幅度）变异性的函数。根据参数的选择，预测的扰动范围在0.2%至1.2%之间。扰动随运动单位数量和平均放电频率的增加而减小，但随运动单位大小的变异性和放电频率的变异性而增加。文中讨论了从声带振动的其他不规则来源中分离出神经抖动的技术。
