Measurement of a Flow in a Larynx Model with a Vocal Fold Vibrating at High Frequencies

在声音分析中，建立一个能够准确预测围绕一对声带振荡、分离和再附着的流动的数学模型是非常重要的，因为流动直接影响到声音的声源。我们已经提出了一个非定常的一维可分可合流动模型，并证实了该模型可以准确地预测低频振荡至4hz的收缩通道内的压力分布。本研究建立了声道振动频率为100 Hz的喉部模型，测量了声道内流动振动、分离和再附着的基本数据，并通过实测结果与计算结果的对比，讨论了数学模型的有效性和需要修正的地方。从测得的压力波中发现，非定常效应在频率高于20 Hz时出现，在频率为50 ~ 80 Hz时，压力波的趋势发生变化。所提出的可分可合流动模型所模拟的压力波在低于趋势变化频率处与实测波吻合较好。通过实验结果与理论结果的对比，我们发现可能由于无法控制声带模型与通道表面之间0.1 mm的间隙或/以及声带周围有效流动宽度与通道宽度的差异过大而导致趋势发生变化。我们必须进一步讨论流动模型和流动可视化方法。

It is very important in voice analyses to establish a mathematical model which can accurately predict a flow oscillating, separating and reattaching around a pair of vocal folds, because the flow affects directly sound source of voice. We already proposed an unsteady one-dimensional separable and reattachable flow model and confirmed that this model can accurately predict pressure distribution in a channel with a constriction oscillating at low frequencies up to 4 Hz.In this research a larynx model with a vocal fold vibrating at 100 Hz was made, fundamental data of the flow vibrating, separating and reattaching in the channel was measured, and the validity and the points to be modified of the mathematical model were discussed based on comparison between the measured and calculated results.It was found from the measured pressure waves that effect of unsteadiness appeared at frequencies higher than 20 Hz and that the trend of the waves changed from 50 to 80 Hz.The pressure waves simulated using the proposed separable and reattachable flow model were in good agreement with the measured waves at frequencies lower than the trend changed.As a result of comparison between the experimental and theoretical results, we found that the change in the trend might occur because we could not control the gap of 0.1 mm between the vocal fold model and the channel surface or/and the difference between the effective flow width and the channel width around the vocal fold might be too large. We must further discuss the flow model and the flow visualization method.