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.