Commentary on why laryngeal stroboscopy really works: clarifying misconceptions surrounding Talbot's law and the persistence of vision

Abstract

Purpose: The purpose of this article is to clear up misconceptions that have propagated in the clinical voice literature that inappropriately cite Talbot's law (1834) and the theory of persistence of vision as the scientific principles that underlie laryngeal stroboscopy.

Method: After initial research into Talbot's (1834) original studies, it became clear that his experiments were not designed to explain why stroboscopy works. Subsequently, a comprehensive literature search was conducted for the purpose of investigating the general principles of stroboscopic imaging from primary sources.

Results: Talbot made no reference to stroboscopy in designing his experiments, and the notion of persistence of vision is not applicable to stroboscopic motion. Instead, two visual phenomena play critical roles: (a) the flicker-free perception of light and (b) the perception of apparent motion. In addition, the integration of stroboscopy with video-based technology in today's voice clinic requires additional complexities to include synchronization with camera frame rates.

Conclusions: References to Talbot's law and the persistence of vision are not relevant to the generation of stroboscopic images. The critical visual phenomena are the flicker-free perception of light intensity and the perception of apparent motion from sampled images. A complete understanding of how laryngeal stroboscopy works will aid in better interpreting clinical findings during voice assessment.