Highspeedglottography with a Exible Endoscope for the Examination of the Human Larynx during Running Speech 2 Recording System and Light-intensiier

A digital high-speed camera in combination with a light intensiier and a exible endoscope is used to record running human speech. Due to the light absorbtion of the exible endo-scope, the recorded image sequences are too dark for human examination and too poor for digital motion analysis. Therefore, two diierent image enhancement methods are compared to improve the image sequences. Resulting trajectories of motion analysis of vocal cord vibrations during running speech will be shown. 1 Motivation The most common method for the examination and diagnosis of functional voice disorders (dysphonias) is video-stroboscopy. Since the unstressed,human voice has a mean frequency in the range between 150 and 300 Hz, but standard video cameras only record at a maximumspeed of 50 half frames per second, the disadvantage of this method is clearly the subsampling of the oscillation of the vocal cords. The examiner registers these oscillations as a so called 'virtual vibration' and therefore cannot judge it properly. With a high-speed camera, however, the vocal cord vibrations can be lmed with a recording rate high enough to observe even asymmetric and aperiodic vibration modes. Furthermore, variations of the amplitude (jitter) and period (shimmer) can be registered. Since these parameters are symptomatic for hoarse or creaky voices 2], the high-speed glottography in combination with semi-automatic motion analysis of vocal fold vibrations can be a mighty tool for the clinical diagnosis. The Department of Phoniatrics in Erlangen has been involved with digital high-speed cameras for about 15 years 6]. For the past three years, a clinically applicable version of a high-speed camera has been in use for the recording of vocal cord vibrations with a grant from the DFG (DFG Ey 15/5-3). This high-speed recording system is based on a commercially available digital high-speed camera (FhG-IIS CAMSYS+) with a full resolution of 128 2 pixel and a maximum recording speed of 10 000 fps. The duration of a