Videostrobokymographic Analysis of Stroboscopic Footage With Unsteady Laryngeal Positions From Phononormals

This study aimed (i) to extract videostrobokymograms (VSK) and measure the objective metrics of vocal fold vibration from stroboscopic footage with unsteady laryngeal positions using a customized approach that utilized the Lucas-Kanade optical flow method-alongside other preprocessing methods and kymogram extraction techniques and (ii) to juxtapose the readings of Electroglottography (EGG) with the extracted VSK metrics.

Sixty-three tokens of videostroboscopy and EGG were obtained from 21 phononormals. The videostroboscopic samples were then subjected to pre-processing for optimization. From the preprocessed samples, VSK were extracted at three lines of interest, ie, anterior, middle, and posterior region of the vocal folds, using a customized approach. Further, closed quotient was computed from the extracted VSK (VSK CQ) and contact quotient from the EGG waveform (EGG CQ). Wilcoxon signed-rank test and Bland-Altman plot analysis were performed to compare and determine the agreements between VSK and EGG values.

VSK obtained in this study were visually similar to the VSK reported in the literature. Mean and SD of EGG CQ was (0.45 ± 0.01), and VSK CQ was (0.46 ± 0.02). The values of VSK CQ differed from the anterior to the posterior portion of the vocal folds, demonstrating variations in movement along its length. Wilcoxon signed-rank test revealed no statistically significant differences between the VSK and EGG measurements. Bland-Altman plot analysis used to compare the agreements between two measurements suggested that VSK values were in agreements with the EGG measurements.

The present work offers preliminary evidence that quantifiable objective measures can be calculated even from videostroboscopic footage with unsteady laryngeal positions by tailoring the VSK technique. However, assessing the clinical value of this approach is mandatory.