title: Graphical evaluation of vocal fold vibratory patterns by high-speed videolaryngoscopy.
abstract: OBJECTIVE
  To characterize the voice and vocal fold function of an individual, it is essential to evaluate vocal fold vibration. The most widely used method for this purpose has been videolaryngoscopy.
  
  
  METHODS
  This article proposes a digital image processing algorithm to estimate the glottal area (ie, the space between the vocal folds) and produce graphs of the opening and closing phases of the glottal cycle. In eight subjects without voice disorders, vocal fold movements were recorded by high-speed videolaryngoscopy at 4000 frames per second. The video data were processed by a combination of image segmentation techniques that estimate the glottal area. The segmented area was used to construct the glottal waveform.
  
  
  RESULTS
  The graphs revealed important properties of vocal fold vibration, including amplitude, velocity, and other characteristics that have a major influence on voice quality.
  
  
  CONCLUSIONS
  The combination of the high-speed technology with the proposed method improves the vocal fold analysis given a numerical feedback through graphical representation of the real vibratory patterns of the folds.
authors.affiliation: Nucleus of Scientific and Technological Development, Faculty of Electrical Engineering, Federal University of Uberlândia, Patos de Minas, Brazil. Electronic address: alan@eletrica.ufu.br.
authors.forename: Alan P
authors.initials: AP
authors.lastname: Pinheiro
authors.affiliation: School of Medicine, University of São Paulo, São Paulo, Brazil.
authors.forename: Maria Eugênia
authors.initials: ME
authors.lastname: Dajer
authors.affiliation: School of Medicine, University of São Paulo, São Paulo, Brazil.
authors.forename: Adriana
authors.initials: A
authors.lastname: Hachiya
authors.affiliation: Department of Electrical Engineering, Federal University of São Carlos, São Carlos, Brazil.
authors.forename: Arlindo N
authors.initials: AN
authors.lastname: Montagnoli
authors.affiliation: School of Medicine, University of São Paulo, São Paulo, Brazil.
authors.forename: Domingos
authors.initials: D
authors.lastname: Tsuji
mesh_terms: D000328:Adult; D000465:Algorithms; D001696:Biomechanical Phenomena; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods*; D007828:Laryngoscopy; D008297:Male; D010363:Pattern Recognition, Automated; D010699:Phonation; D011237:Predictive Value of Tests; D012016:Reference Values; D013997:Time Factors; D014732:Vibration; D014741:Video Recording; D014827:Vocal Cords / Q000033:anatomy & histology / Q000502:physiology*; D014833:Voice Quality
keywords: Glottal area; High-speed imaging; Segmentation; Videolaryngoscopy