Videokymography System, Model 8900

The Videokymography (VKG) System, Model 8900, was designed for the direct observation of vocal fold vibratory characteristics. Using a modified video camera, coupled to a standard rigid endoscope and constant light source, VKG is capable of capturing high-speed motion such as vocal fold vibration. The VKG camera scans a single line at 8000 lines/second, which is recorded to a standard videocassette recorder for review and analysis.

Developed at the University of Groningen, the Netherlands, by Dr. Harm Schutte and Dr. Jan Švec, and clinically tested by Dr. František Šram (Center for Communication Disorders, Medical Healthcom, Ltd., Prague, Czech Republic), the videokymographic technique has been used to evaluate hundreds of patients, therein establishing its clinical value. Researchers can also benefit from the information regarding vocal fold dynamics gained using this powerful technique. Videokymographic images reflect important properties of vocal fold vibration, including open and closed phases of the glottal cycle, opening and closing movements, displacements of the upper and lower vocal fold margins, and propagation of mucosal waves.

The two modes of the VKG camera are shown above. The standard mode displays a black-and-white video image for proper orientation. In high-speed mode, a single line selected from the standard image is displayed approximately 8000 times per second.

 

• New technique for observing vocal fold vibratory characteristics 

• Ideal complement to stroboscopy

• High-speed line scanning (8000 lines/second) of the vocal folds

• Information obtained similar to high-speed film at a fraction of the cost

• Accurate representation of physiology in all vocal behaviors

• Switchable between standard b/w composite video and high-speed modes

• Developed and tested in acclaimed research lab and voice clinic

• Usable with most constant light sources and rigid endoscopes 

Standard vs. High-Speed Mode

The videokymography camera offered by KayPENTAX functions in either standard or high-speed mode. The standard mode presents a black-and-white composite video image. In standard mode, the frame rate is 60 Hz (NTSC) or 50 Hz (PAL). This mode is used to properly position the endoscope for data recording during the high-speed mode.

In high-speed mode, the camera scans a single line from the standard image at a rate of nearly 8000 lines/second. With each line displayed on the monitor in succession, a time history representing successive glottal cycles is produced. Clinicians may position the endoscope to “select” which portion of the vocal folds (e.g., middle, anterior commissure, etc.) is observed. A foot pedal allows the clinician to easily switch between the standard and the high-speed modes. KayPENTAX also offers a switch/distribution system (with S-Video/BNC input and S-Video/BNC outputs) to allow easy switching between the standard color camera used for stroboscopy and the black-and-white videokymography camera.

Complement to Stroboscopy

Given its unique capabilities, VKG is the ideal complement to stroboscopy. Although the full screen display of the VKG “image” constituted of single lines is not as intuitive as stroboscopy, VKG does allow direct viewing of vocal fold behaviors which may not be observable with a stroboscopic image. For example, the high scan rate of 

VKG allows the direct observation of vocal fold motion, even if the motion is aperiodic. Thus, voicing initiation, diplophonia, biphonia, vocal fry, creaky voice, and aperiodicity can all be viewed directly. Even in normal quasi-periodic phonation, vocal asymmetry and mucosal waves are clearly visible with this powerful technique.

VKG promises to fill a key role in broadening the understanding of phonatory dynamics. The VKG System complements the complete KayPENTAX line of voice instrumentation used by clinicians and researchers throughout the world. KayPENTAX offers competitive pricing and excellent support for all of its products.

For further information about the Videokymography System, contact KayPENTAX or your local representative.

Specifications

Image Sensor System: 

Lens Mount: C-Mount

Dimensions: 40 x45 x153 mm (1.6' x1.8" x6"

Weight: 250 g (8.8 oz.)

See, also:

• Digital Strobe
• Optimizing Videokymographic Image Quality
• Videokymography Videotape Available
• Dr. Švec's Electronic Dissertation