title: Visualizing phase relations of the vocal folds by means of high-speed videoendoscopy.
abstract: OBJECTIVE
  To present a method called Fourier image (FI) for analyzing high-speed videoendoscopy recordings. These false-color images visualize functional vocal fold properties and allow the quantification of phase relations. Furthermore, reference data for phase asymmetries in normophonic speakers as assessed with this method are provided.
  
  
  METHODS
  Prospective study.
  
  
  METHODS
  Phase relations between parts of the vocal folds were assessed using Fourier analysis of the grayscale fluctuations of corresponding pixel within the endoscopic high-speed videos. This phase information was displayed by means of colors and can thus be used to quantify left-right or anterior-posterior phase asymmetries. These phase relations were assessed in 11 normophonic speakers.
  
  
  RESULTS
  Several instructive examples are given, which demonstrate how the FIs can be interpreted. From the cohort of clinically normophonic speakers, all but one displayed at least some extent of phase asymmetry.
  
  
  CONCLUSIONS
  The method presented herein can be used to display functional vocal fold properties including the absence of oscillation, glottal insufficiency, and phase relations within one single image. The reference data showed that phase asymmetries seem to be frequent even in normophonic speakers.
authors.affiliation: C. Doppler Laboratory for Active Implantable Systems, Institute of Ion Physics and Applied Physics, University of Innsbruck, Innsbruck, Austria. andreas.krenmayr@medel.com
authors.forename: Andreas
authors.initials: A
authors.lastname: Krenmayr
authors.forename: Thomas
authors.initials: T
authors.lastname: Wöllner
authors.forename: Nicola
authors.initials: N
authors.lastname: Supper
authors.forename: Patrick
authors.initials: P
authors.lastname: Zorowka
mesh_terms: D000328:Adult; D005260:Female; D005583:Fourier Analysis; D006801:Humans; D007828:Laryngoscopy; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D014741:Video Recording; D014827:Vocal Cords / Q000502:physiology*; D055815:Young Adult