Non-contact optical sensing of vocal fold vibrations by secondary speckle patterns

Vocal folds lesions are commonly diagnosed using an endoscopic-stroboscope. However, the stroboscopic picture of the vocal folds vibrations is subjectively and qualitatively evaluated by the clinician and, due to technical limitations, is unable to accurately distinguish between healthy and pathologic regions. In this paper, we propose two optical approaches for objectively sensing the vocal folds vibrations, using either external or internal laser illumination, based on temporal tracking of the reflected spatial distribution of secondary speckle patterns. The external configuration (the neck) is noninvasive and the internal configuration (the larynx) allows simultaneous extraction of data from multiple sites on the vocal folds. In this paper, we present measurements of healthy human subjects. Quantitative and precise measurements of vibration parameters of the vocal folds will enable a better understanding of hidden pathologies and optimize the diagnosis and treatment.