Using active shape modeling based on MRI to study morphologic and pitch-related functional changes affecting vocal...

Area of Science:

• Biomedical Engineering
• Speech Science
• Medical Imaging

Background:

• Vocal tract shape is complex and varies with development and function, complicating voice analysis.
• Traditional measurement methods struggle to quantify shape differences and inter-structure movement.
• Statistical shape models offer a way to characterize shape variations by independent modes.

Purpose of the Study:

• To develop an active shape model (ASM) for assessing morphologic and pitch-related functional changes in vocal structures and the airway.
• To quantify shape variations in the vocal tract and associated structures.
• To understand how vocal structures move in relation to each other during pitch changes.

Main Methods:

• Cross-sectional study design with midsagittal magnetic resonance imaging (MRI) of 10 healthy adults.
• Data acquired at rest, during exhalation, and while humming low and high notes.
• Eighty landmark points defined the shape of interest, and an ASM was built using 60 images. Principal Component Analysis identified modes of variation.

Main Results:

• Twenty modes of variation were identified, with the first two explaining 50% of the total variance.
• Modes 1 and 9 significantly correlated with humming low and high notes, respectively (P < 0.001).
• These modes demonstrated coordinated changes in the cervical spine, vocal structures, and airway. Mode 2 showed significant inter-subject structural variation.

Conclusions:

• Active shape modeling is a promising tool for understanding morphologic and pitch-related functional variations in the vocal tract.
• This approach can advance the study of vocal structures and airway dynamics in both healthy individuals and those with disease.
• The findings provide insights into the biomechanics of voice production and vocal tract variability.