Revealing vocal-fold stroboscopic movements side by side

Q. Qiu

Objective: Most pathological phonation exhibits asymmetric movement in which the vocal-fold vibrations differ from one side to the other. When the two vocal folds have periodically asymmetric movements, traditional stroboscopy fails to reveal the vocal-fold movement because of triggering difficulties. This study presents a new triggering method for stroboscopy to investigate such pathological vocal-fold movements one side at a time.
Methods: A line-scan camera is attached on a flash-free stroboscopic camera by using a custom-made optical coupler, in which a beam-splitter optically divides the image into two parts, one for the stroboscopic camera and the other for the line-scan camera. With 7200 lines per second, the line scan camera records a line image sequence of vocal-fold movement perpendicular to the glottal axis. Simultaneously, the flash-free stroboscopic camera uses its electronic shutter to generate single-side vocal-fold stroboscopic movements according to the fundamental frequency of the vocal-fold movement of that same side. This frequency is calculated by a real-time digital image processor from the line-scan image sequence.
Results: 2 subjects with unilateral laryngeal paralysis were investigated by the present flash-free stroboscopic and newly developed single-sided triggering system. When the audio signal is used for triggering, the stroboscopic movement cannot be revealed because no uniform frequency can be detected. However, a fundamental frequency can be obtained from a single side vocal-fold vibratory image, revealing the vocal-fold stroboscopic movement of that side. The experimental results from the 2 subjects show in both cases the expected difference between the vocal folds sides.
Conclusions: The method presented introduces a new tool to reveal the stroboscopic vocal-fold movement one side at a time, thus enhancing the power of stroboscopy for clinical diagnosis.

CV:
Q.Qiu is an engineer pecialized in voice and voice physiology. He received the Bachelor of Engineering degree from Tianjin Medical University, Tianjin, China, in 1996, the Master of Science degree and Ph.D. degree of Biomedical Engineering in 1999, and 2002, respectively, from Tianjin University, Tianjin, China. In September 2003, he joined the Groningen Voice Research Lab at the University of Groningen, Groningen, the Netherlands. He is interested in all aspects of biomedical imaging especially for voice research. He has published over 20 papers.

Corresponding information:

Q. Qiu Groningen Voice Research Lab, Department of Biomedical Engineering, Artificial Organs, University of Groningen, A.Deusinglaan 1, 9713 AV, Groningen, the Netherlands.+31-50-3638162 e-mail: q.qiu@med.umcg.nl

J.G. Švec Groningen Voice Research Lab, Department of Biomedical Engineering, Artificial Organs, University of Groningen, A.Deusinglaan 1, 9713 AV, Groningen, the Netherlands.+31-50-3638162 e-mail: j.g.svec@med.umcg.nl

H.K. Schutte Groningen Voice Research Lab, Department of Biomedical Engineering, Artificial Organs, University of Groningen, A.Deusinglaan 1, 9713 AV, Groningen, the Netherlands.+31-50-363 2688 e-mail: h.k.schutte@med.umcg.nl

Q. Qiu^(a), J.G. Svec^(a), H.F. Mahieu^(b,c), T.A. van Kalkeren^(c) and H.K. Schutte^(a)

(a)Groningen Voice Research Lab, Department of Biomedical Engineering, Artificial Organs, University of Groningen, A.Deusinglaan 1, 9713 AV, Groningen, the Netherlands

(b)Department of Otorhinolaryngology and Head and Neck Surgery, Free University Medical Center Amsterdam, Amsterdam, The Netherlands.

(c)Department of Otorhinolaryngology and Head and Neck Surgery, Meander Medical Centre, Amersfoort, The Netherlands.