title: Phase difference of vocally healthy subjects in high-speed digital imaging analyzed with laryngotopography.
abstract: BACKGROUND
  To elucidate the vibratory patterns of the vocal folds in normophonic subjects, we conducted a prospective study with laryngotopography, an analyzing technique for high-speed digital imaging to intuitively grasp spatial characteristics of vocal fold vibrations by pixel-wise discrete Fourier transform for brightness curve.
  
  
  METHODS
  Vocally healthy volunteer subjects with neither vocal complaint nor history of laryngeal diseases were divided into young (aged 35 years and younger) and elderly groups (aged 65 years and older), and high-speed digital images of phonations at a conversational frequency were analyzed with laryngotopography: phase differences (PDs) in the anterior-posterior (longitudinal) direction and in the left-right (lateral) direction were assessed.
  
  
  RESULTS
  Twenty-six young subjects (nine men and 17 women with a mean age of 27 years) and 20 elderly subjects (eight men and 12 women with a mean age of 73 years) were assigned to our study. In longitudinal PD, posterior-to-anterior opening type was significantly frequent in young women (all subjects: 43% and young women: 94%; P<0.001), whereas anterior-to-posterior opening type was significantly frequent in elderly men (all subjects: 39% and elderly men: 88%; P<0.001). There were no age- or gender-related differences in lateral PD (all subjects: 65%; P=0.880).
  
  
  CONCLUSIONS
  Both longitudinal and lateral PDs were widely observed even in vocally healthy subjects. Furthermore, the age- and gender-specific characteristics were also classified. Laryngotopography serves as a powerful tool to quantitatively characterize the vibratory patterns of vocal folds in vocally healthy subjects.
authors.affiliation: Department of Otolaryngology, the University of Tokyo Hospital, 7-3-1, Hongo, Bunkyo-ku, Tokyo, Japan. drachilles23@yahoo.co.jp
authors.forename: Akihito
authors.initials: A
authors.lastname: Yamauchi
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Imagawa
authors.forename: Ken-Ichi
authors.initials: K
authors.lastname: Sakakibara
authors.forename: Hisayuki
authors.initials: H
authors.lastname: Yokonishi
authors.forename: Takaharu
authors.initials: T
authors.lastname: Nito
authors.forename: Tatsuya
authors.initials: T
authors.lastname: Yamasoba
authors.forename: Niro
authors.initials: N
authors.lastname: Tayama
mesh_terms: D000328:Adult; D000368:Aged; D000375:Aging / Q000502:physiology; D005260:Female; D005583:Fourier Analysis; D006801:Humans; D007090:Image Interpretation, Computer-Assisted; D008297:Male; D011446:Prospective Studies; D012016:Reference Values; D012727:Sex Characteristics; D013061:Speech Acoustics; D014732:Vibration; D014827:Vocal Cords / Q000502:physiology*; D055815:Young Adult