title: Sound spectral analysis of snoring sound and site of obstruction in obstructive sleep apnea syndrome.
abstract: CONCLUSIONS
  This study demonstrates that there is a significant difference in sound spectrum between first snoring sound after upper level and lower level obstructive apneas, and it is possible to use sound spectrum analysis as a supplementary method to determine the obstructive site of a patient with obstructive sleep apnea syndrome (OSAS).
  
  
  OBJECTIVE
  To investigate the difference in sound spectrum between the first snoring sounds after upper level (above the free margin of soft palate) obstructive apneas and lower level (below the free margin of soft palate) obstructive apneas in patients with OSAS.
  
  
  METHODS
  Thirty male patients with OSAS were included in this study. Overnight snoring sound was recorded and continuous upper airway pressure measurement was performed simultaneously on each subject. The first snores after upper level and lower level obstructive apneas were identified and analyzed acoustically.
  
  
  RESULTS
  The mean of peak frequencies, central frequencies, and proportions of energy from 800 Hz to 2000 Hz and above 2000 Hz of the first snoring sounds after lower level obstructive apneas were higher and the proportion of energy below 800 Hz was lower than those after upper level obstructive apneas. The differences of all the parameters were of significance. The power spectrum of the two types of snoring sounds also exhibited different characters.
authors.affiliation: Department of Otolaryngology, Beijing Hospital, PR China.
authors.forename: Huijie
authors.initials: H
authors.lastname: Xu
authors.forename: Weining
authors.initials: W
authors.lastname: Huang
authors.forename: Lisheng
authors.initials: L
authors.lastname: Yu
authors.forename: Lan
authors.initials: L
authors.lastname: Chen
mesh_terms: D000328:Adult; D006801:Humans; D008297:Male; D017286:Polysomnography / Q000379:methods; D012189:Retrospective Studies; D012720:Severity of Illness Index; D020181:Sleep Apnea, Obstructive / Q000150:complications* / Q000503:physiopathology; D012913:Snoring / Q000175:diagnosis* / Q000209:etiology / Q000503:physiopathology; D013018:Sound Spectrography / Q000379:methods*