title: Noninvasive monitoring of vocal fold vertical vibration using the acoustic Doppler effect.
abstract: OBJECTIVE
  To validate a proposed method of noninvasively monitoring vocal fold vertical vibration through utilization of the acoustic Doppler effect and the waveguide property of the vocal tract.
  
  
  METHODS
  Validation case-control study.
  
  
  METHODS
  In this device, an ultrasound beam is generated and directed into the mouth. The vocal tract, acting as a natural waveguide, guides the ultrasound beam toward the vibrating vocal folds. The vertical velocity of vocal fold vibration is then recovered from the Doppler frequency of the reflected ultrasound. One subject (age 32, male) was studied and measurements were taken under three modes of vocal fold vibration: breathing (no vibration), whispering (irregular vibration), and normal phonation (regular vibration).
  
  
  RESULTS
  The peak-to-peak amplitude of the measured velocity of vocal fold vertical vibration was about 0.16 m/s, and the fundamental frequency was 172 Hz; the extracted velocity information showed a reasonable waveform and value in comparison with the previous studies. In all three modes of phonation, the Doppler frequencies derived from the reflected ultrasound corresponded with the vertical velocity of vocal fold vibration as expected.
  
  
  CONCLUSIONS
  The proposed method can accurately represent the characteristics of different phonation modes such as no phonation, whisper and normal phonation. The proposed device could be used in daily monitoring and assessment of vocal function and vocal fold vibration.
authors.affiliation: Key Lab of Modern Acoustics and Institute of Acoustics, Ministry of Education, Nanjing University, Nanjing, People's Republic of China.
authors.forename: Chao
authors.initials: C
authors.lastname: Tao
authors.forename: Jack J
authors.initials: JJ
authors.lastname: Jiang
authors.forename: Dan
authors.initials: D
authors.lastname: Wu
authors.forename: Xiaojun
authors.initials: X
authors.lastname: Liu
authors.forename: Ann
authors.initials: A
authors.lastname: Chodara
mesh_terms: D000328:Adult; D001696:Biomechanical Phenomena; D016022:Case-Control Studies; D004301:Doppler Effect; D006801:Humans; D008297:Male; D010699:Phonation; D015203:Reproducibility of Results; D012119:Respiration; D013018:Sound Spectrography; D013997:Time Factors; D014465:Ultrasonics / Q000379:methods*; D014732:Vibration; D014827:Vocal Cords / Q000502:physiology*; D014831:Voice