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

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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.