Non-stationary Modeling of Vocal Fold Vibrations During a Pitch Raise

In clinical examination, vocal fold vibrations are usually visualized during a stationary sustained phonation. This experimental condition is easy to handle, but does not reflect the voice in every day life. The objective of this study is to investigate the laryngeal mechanism during a non-stationary phonation. A monotonous pitch raise paradigm (MPRP) as an example of a non-stationary phonation is considered. An extension of the biomechanical two-mass-model (2MM) with time-dependent parameters is developed to model vocal fold vibrations and belonging physiological parameters. The procedure iteratively adapts the extended 2MM via frequency and amplitude matching to real vibrations of vocal fold edges, obtained from an endoscopic investigation with a high-speed camera system (high-speed glottography, HGG). In simulations the proposed fitting scheme is capable to approximate the non-stationary oscillation of the vocal folds. The verification of the algorithm is exemplarily demonstrated with a synthetically generated data set and recordings of a female subject with normal voice. The time-dependent model parameters adjusted by the proposed inversion algorithm are estimates of the adaptation of the vocal folds during a non- stationary phonation.