A Real-Time Slow-Motion Video Storboscope for NON-Intrusive Diagnostics of the Larynx Vibration

The endovideostroboscopy of the larynx became a powerful tool for the study of vocal physiology, assessment of the fold abnormalities, motion impairments and functional disorders, as well as for the early diagnosis of vocal cord diseases like cancer and pathologies like nodules, carcinoma, polyps and cysts. A novel computer controlled high-speed video stroboscope has been developed and applied for the examination and recording of human laryngeal vibration. In contrast to the standard stroboscopes it does not utilie pulsed light for the objekt illumination. Instead, a special asynchronously shuttered video camera triggered by the oscillating object has been used. In the case of the larynx inspection the trigger pulses have been picked up via a laryngophone. The stroboscope system includes a specially designed and patented digital phase shifter. This device generates a frequency independent phase shift according to the on-screen edited table. The phase can be changed with an adjustable speed in user selected steps. Thus, the stroboscope provides a stop phase and slow motion observation in real time with simultaneous recording of the periodically moving objects, i.e. the desired position of the folds or their virtual slowed down vibration speed does not depend of the voice pitch. Sequences of hundreds of high resolution frames (660H x 494V or 762H x 582V according to the EIA or CCIR standards, respectively) can be stored on the hard disk in the BMP, compressed TIFF or AVI formats. Afterwards they can be played back frame-by-frame or as a video sequence, evaluated, exported, printed out and transmitted via computer networks. This System principel and the application results in form of recorded frame sequences are presented