The effects of excessive vocalization on acoustic and videostroboscopic measures of vocal fold condition

Although dysphonia is a recognized consequence of acute vocal abuse, associ ated changes in vocal fold appearance and function are not well understood. To document these presumed effects of vocal abuse, audio recordings of sus tained vowel production were obtained from 42 drill sergeants daily during the first 6 days of a vocally demanding training exercise. Acoustic analysi s showed abnormal levels of jitter and shimmer on Day 1 in 16 of the 42 sub jects. Considering only the 26 subjects who showed normal voice acoustics o n Day 1, the median levels of jitter and shimmer varied little over the cou rse of training, and significant increases in jitter and shimmer were not s een during the study period. However, the distributions for both jitter and shimmer became more positively skewed and showed a greater number of posit ive outliers over the course of training. This trend was attributed to 11 s ubjects who showed two or more instances of abnormal voice acoustics over D ays 2 through 6. Laryngeal videostroboscopic recordings of sustained vowel production also were obtained prior to and following training. Perceptual r atings of these recordings by 2 observers revealed significant increases in vocal fold edema, erythema, and edge irregularity, and decreases in vocal fold mucosal wave and amplitude of excursion following the 5-day training p eriod. In,general, there was considerable intersubject variability in the e xtent of acoustic and videostroboscopic effects over the course of training . Of the two types of data, videostroboscopy appears to provide a more sens itive indication of the effects of excessive vocalization.