Estimation of lumped vocal fold mechanical properties from non-invasive microphone recordings

In this paper it is argued that vertical motions of the vocal folds allow sound to be transmitted between the subglottal airways and the vocal tract during the closed phase of vocal fold vibration. From this insight, a pair of equations relating the lumped inertance and compliance of the vocal folds to the frequencies of speech resonances (F0 and formants) is derived. These equations include terms for the input impedances of the vocal tract and the subglottal airways measured from the glottis. If these input impedances can be estimated with sufficient accuracy, then the lumped inertance and compliance of the vocal folds can be estimated to arbitrary accuracy depending on the accuracy of formant and F0 measurements, and depending on the validity of the assumptions that losses are negligible and that the vocal folds are mechanically isotropic in the coronal plane.