Howe M S, McGowan R S
Boston University, College of Engineering, 110 Cummington Street, Boston MA 02215.
Fluid Dyn Res. 2010 Jan 18;42(1):15001. doi: 10.1088/0169-5983/42/1/015001.
An analysis is made of the fluid-structure interactions necessary to support self-sustained oscillations of a single-mass mechanical model of the vocal folds subject to a nominally steady subglottal overpressure. The single-mass model of Fant and Flanagan is re-examined and an analytical representation of vortex shedding during 'voiced speech' is proposed that promotes cooperative, periodic excitation of the folds by the glottal flow. Positive feedback that sustains glottal oscillations is shown to occur during glottal contraction, when the flow separates from the 'trailing edge' of the glottis producing a low pressure 'suction' force that tends to pull the folds together. Details are worked out for flow that can be regarded as locally two-dimensional in the glottal region. Predictions of free-streamline theory are used to model the effects of quasi-static variations in the separation point on the glottal wall. Numerical predictions are presented to illustrate the waveform of the sound radiated towards the mouth from the glottis. The theory is easily modified to include feedback on the glottal flow of standing acoustic waves, both in the vocal tract beyond the glottis and in the subglottal region.
对声带单质量力学模型在名义上稳定的声门下超压作用下支持自持振荡所需的流固相互作用进行了分析。重新审视了范特（Fant）和弗拉纳根（Flanagan）的单质量模型，并提出了“浊音语音”过程中涡旋脱落的解析表示，该表示促进了声门气流对声带的协同、周期性激励。研究表明，在声门收缩期间，当气流从声门的“后缘”分离产生一个趋于将声带拉拢在一起的低压“吸力”时，会出现维持声门振荡的正反馈。详细研究了在声门区域可视为局部二维的气流情况。采用自由流线理论的预测来模拟声门壁上分离点的准静态变化的影响。给出了数值预测结果，以说明从声门向口腔辐射的声音波形。该理论很容易修改，以纳入声门之外的声道以及声门下区域中驻波对声门气流的反馈。
