Studying Vibratory Patterns of Vocal Folds and their Impairments in Parkinson's Disease: A Theoretical Approach

Abstract

Current vocal fold models emphasize either time or space during voice production but leave the source unconsidered. In the present review paper, we studied the vocal fold oscillations by dividing them into two zones. Zone 1 contains the brain, neurons, and vagus nerve, and zone 2 comprises mechanical apparatus including lungs, voice box, and articulators. Then, a zonal view of changes in the voice, and vocal impairments due to Parkinson’s disorder is demonstrated. The paper further examines various mathematical models analyzing vocal fold oscillations and their respective limitations. Since voice production is a cause-and-effect relationship, thus we used double point Green’s Function method to solve the problem of vocal fold oscillation. This adds the causality factor and delay term to the problem and also illustrates the potential problems that could arise during the creation, conversion, or transition of impulses during speech production. Hence, our approach addresses the problem at the time when sound waves are in the form of electromagnetic impulses in the brain. Due to a lack of test subjects, however, we are unable to evaluate the experimental outcomes of this approach. Finally, the paper also mentions some unexplored limitations, which can be elucidated in the future.