The effects of intraoral pressure change on F0 regulation--preliminary study for the evaluation of vocal fold stiffness.

This study was intended to evaluate the stiffness of the vocal folds noninvasively. As a first step, the relationship between vocal fundamental frequency (F0) and intraoral pressure (P0) was investigated. F0 was recorded during production of forced P0 changes in three men and four women while they uttered sustained vowels. The pressure changes were applied by closing a valve mounted on a mouthpiece. Changes in F0 as a function of changes in P0 (dF0/dP0) were then measured. The values of dF0/dP0 varied with F0 in a manner inherent to each subject. The relationship between dF0/dP0 and F0 was found to have a potential benefit for the evaluation of stiffness at a specific length of vocal fold.