Noncontact Determination of the Mechanical Properties of the Human Vocal Folds

Mechanical properties of the vocal folds (such as stiffness or viscoelastic properties) play an essential role in phonation. They affect not only voice quality but also onset threshold of vocal fold self-excited oscillation, a sound source of voice [1]. Many experimental data on the mechanical properties have been reported so far, in which in vitro [2] or in vivo measurement techniques [3] were employed. In vitro measurements give us detailed information on the mechanical properties, yet it would be required to consider possible loss of freshness of the specimen. Meanwhile, current in vivo measurement methods utilize a thin probe to deform the vocal fold tissue located at the back of the throat and hence need technical skills for the surveyor to successfully obtain its loading-deformation relationship.