Three-dimensional Vocal Tract Morphology Based on Multiple Magnetic Resonance Images Is Highly Reproducible During Sustained Phonation.

OBJECTIVES: The extraction of a three-dimensional (3D) morphology of the human vocal tract (VT) from magnetic resonance imaging (MRI) during sustained phonation can be used for various analyses like numerical simulations or creating physical models. The precision of visualizing techniques nowadays allows for very targeted acoustical simulation evaluating the influence of subsections of the VT for the transfer function. The aim of the study was to assess the accuracy of the 3D geometry based on MRI data in repetitive trials.

STUDY DESIGN: This is a prospective study.

METHODS: Four experienced singers underwent an MRI while repeating a specific vocal task 20 times consecutively. Audio recordings were made by means of an optical microphone. Images were restacked and subsections of the VT were segmented on multi-image-based cross sections using a semiautomatic algorithm. Different volume and area measures were evaluated.

RESULTS: A high reproducibility of the morphologic data based on multiple images by means of the applied segmentation method could be shown with an overall variation of around 8%.

CONCLUSIONS: 3D modeling of the VT during sustained phonation involves a complex experimental setting and elaborate image processing techniques. Functional comparative analysis or acoustical simulations based on such data should take the found variability into account.