A Spatiotemporal Approach to the Objective Analysis of Initiation and Termination of Vocal-fold Oscillation With High-speed Videoendoscopy.

High-speed videoendoscopy excels in the ability to observe the vocal-fold oscillatory patterns during voice initiation and termination. The initial and most critical step in the analysis of these transient regions is to identify the locations of these transient periods, that is, determining when the vocal-fold oscillation is absent and when the oscillation has reached its steady-state behavior. The latter is more challenging as the "steady" oscillation during sustained phonation is not truly steady and is expected to vary over time. This variation may cause unreliable identification of the transient periods, possibly resulting in less accurate or less reliable parameter measurements. An oscillation feature that is relatively consistent in the steady state is the glottal length, that is, the extent of the oscillation along vocal folds. This paper proposes an autonomous algorithm to estimate the vocal-fold oscillation length and its use to detect four transient events: oscillation onset and offset, and attainment and loss of full-length oscillation. The detected event markers are intended to be used to improve the transient parameter measurements. The autonomous algorithm manipulates the set of glottal width waveforms spatiotemporally to estimate the oscillation length. Examples with in vivo high-speed videoendoscopy recordings of both normal and pathological cases are included to show the efficacy of the proposed algorithm to identify the transient markers.