Objective Measures of Stroboscopy and High-Speed Video.

Videostroboscopy and high-speed imaging is now an accepted way to evaluate laryngeal function in patients with voice disorders. In patients with neurolaryngological diseases such as tremor, laryngeal spasm, and paralysis, having an objective way to evaluate vocal function is desirable. Using digital imaging and analysis, both the videostroboscopy and the high-speed video can be analyzed to obtain relevant measures of vocal function. From the videostroboscopy, the montage of the glottal cycle derived from steady of vocal vibration can be analyzed by using edge tracking software to obtain the glottal area waveform. The waveform is an indication of the efficiency of the vocal folds in acting as an oscillator and gives direct information as to the open and closed phase, the symmetry of vocal fold vibration and the degree of amplitude contribution from each fold. High-speed video overcomes the deficiencies of stroboscopy by allowing for all voice gestures to be studies. Using digital kymography and analysis of the vibrogram, analysis of the onset of vocal fold oscillation, evaluation of diplophonia, tremor, and voice breaks becomes possible. Furthermore, analysis of the high-speed video kymograph tracing using signal analysis allow the investigator to evaluate the frequency and power relationships of vocal fold vibratory function in the normal and disordered state.