|Empirically-Based Kinematic Relationships for Vocal Fold Deformation
Jan G. Švec*, Ingo R. Titze†*, Peter S. Popolo*
*Wilbur James Gould Voice Center
The Denver Center for the Performing Arts
† Department of Speech Pathology and Audiology and
National Center for Voice and Speech
The University of Iowa
Excessive or long-lasting repetitive deformations of the vocal folds are suspected to be the cause of occupational voice disorders. The first theoretical analyses on the problem of quantifying the amount of voice exposure (voice dosimetry) show the need for measurement of the time exposure of the vocal folds to vibration, as well as factors such as fundamental frequency, amplitude of vibration, length and thickness of the vocal folds. The measurements of the vibratory amplitude, length and thickness of the vocal folds in phonation, however, are technically difficult to solve. A possible way of bypassing such a difficulty is to use empirically derived rules that relate the vibratory amplitude, length and thickness of the vocal folds to the fundamental frequency and SPL of voice. The present paper reviews the available empirical data on these vocal fold parameters on the basis of which it derives such preliminary mathematical relationships. These empirical relationships allow computation of different vocal doses quantifying exposure of the vocal folds to vibration. The long-term goal of the project is to use the empirical rules and the calculated doses as the basis for establishing the safety criteria of vocalization.