Vocal tract changes caused by phonation into a tube: A case study using computer tomography and finite-element modeling

TLDR

Phonation into a glass tube is a voice training method that has beneficial effects, yet the changes in the vocal tract during and after phonation were previously unknown. This pilot study examined vocal tract shape before, during, and after tube phonation in a female subject. Three‑dimensional finite‑element models derived from CT images were used to analyze changes in vocal tract input impedance. Phonation on vowel [a:] tightened velopharyngeal closure, enlarged oropharyngeal and oral cross‑sections, increased input inertance, and raised acoustic energy radiated, with these changes persisting after tube removal and potentially aiding voice production.

Abstract

Phonation into a glass tube is a voice training and therapy method that leads to beneficial effects in voice production. It has not been known, however, what changes occur in the vocal tract during and after the phonation into a tube. This pilot study examined the vocal tract shape in a female subject before, during, and after phonation into a tube using computer tomography (CT). Three-dimensional finite-element models (FEMs) of the vocal tract were derived from the CT images and used to study changes in vocal tract input impedance. When phonating on vowel [a:] the data showed tightened velopharyngeal closure and enlarged cross-sectional areas of the oropharyngeal and oral cavities during and after the tube-phonation. FEM calculations revealed an increased input inertance of the vocal tract and an increased acoustic energy radiated out of the vocal tract after the tube-phonation. The results indicate that the phonation into a tube causes changes in the vocal tract which remain also when the tube is removed. These effects may help improving voice production in patients and voice professionals.