Using beam elements to model the vocal fold length in breathy voicing.
Mark Anthony Johnson · The Journal of the Acoustical Society of America · 1992
During breathy voicing, the vocal folds close in a zipperlike fashion from front to back, rather than closing all at once as they do during modal voicing [D. H. Klatt and L. C. Klatt, J. Acoust. Soc. Am. 87, 820–857 (1990)]. The two-mass model of fold vibration can only simulate this nonuniform closure if it is modified to allow nonuniform displacement along the length of the folds. A simple model is obtained if the rigid masses of the two-mass model are replaced by three-node Mindlin beam elements, with the anterior and posterior ends of each beam pinned. During modal voicing, the two-beam model is almost identical to the two-mass model. With the arytenoids separated for breathy voicing, the two-beam model behaves like the two-mass model, until the folds start to close. As the beam elements close from front to back, the shear stiffness of the open part increases relative to its mass, so that the back part never quite closes. The combination of gradual closure and posterior ducting gives the spectral tilt characteristic of breathy voicing. Waveforms and spectra from preliminary simulation will be presented. [Research supported in part by an NIH grant.]