Functional imaging of vocal fold vibration: Digital multislice high-speed kymography

For the diagnosis of voice disorders, and especially for the classification of hoarseness, direct observation of vocal fold vibration is essential. Fu rthermore, a quantitative description of the movement of the vocal fold bec omes increasingly necessary to document and compare findings as well as the progression of speech therapy. On the base of digital high-speed sequences of vocal fold vibration, multiple "functional images"-also called digital kymograms-are obtained using image- and signal-processing algorithms. Digit al kymograms can serve as a powerful aid for visualization, description, an d classification of vocal fold vibration and as an intermediate step for im age interpretation by biomechanical modeling. This visualization technique will be discussed and compared to other techniques currently available: vid eokymography and videostroboscopy. The technique is applied to several clin ical examples: aperiodic processes (phonation onset), irregular vocal fold vibration (paralysis of the recurrent nerve), particular vibration modes (a nterior-posterior modes), and running speech.