HISTORY
To visualize vocal fold vibration, especially for disordered vibration, kymographic imaging has gradually become a useful method since Gall and Hanson first introduced kymography to register the motion of the vocal folds in 1971.{GALL1971B} In their research, a special photo-camera with a slit shutter was used to expose the vocal-fold movement onto the film, which is known as photo-kymography. The main problem of the method is extremely time-consuming, because the film needs to be developed, which results in that the photo-kymography can hardly be used in routine clinical diagnosis.{GROSS1985}
Fortunately, videokymography (VKG),{SVEC1996A} where the kymographic image is encoded as a standard video signal, can reveal the vocal fold kymogram immediately on a standard video monitor without any preparation time. Hence, the real-time imaging technique was rapidly introduced into voice research and clinical application. Schutte et al. reported the first clinical application in 1998. In their report, more than 800 patients with various functional and organic voice disorders were examined.{SCHUTTE1998A} Jiang, et al. used the videokymography to quantify vocal fold mucosal wave movements in canine larynges.{JIANG2000C} Verdonck-de Leeuw, et al. combined videokymographic image sequences and speech signals to evaluate the effect of irregular vocal fold vibration on voice quality.{VERDONCKDELEEUW2001}
A common conclusion from these researches was that with high spatial and temporal resolution, videokymography would be a very valuable method for voice disorder diagnosis and a powerful tool for better understanding the mechanism of the vocal fold vibration. However, several drawbacks of the first generation VKG, which were illustrated in the features section, make the progress of its application slow down in recent five years.
Therefore, in the our study, a new generation videokymographic system is developed, where the advantages of the first generation VKG are inherited and the problems of it are fully solved.