title: Sound analysis of catathrenia: a vocal expiratory sound.
abstract: OBJECTIVE
  Catathrenia (nocturnal groaning) is a rare and relatively little-understood parasomnia. The characteristics of the sound and the recordings are not similar in all the relevant research papers. Indeed, there is currently some discussion regarding whether or not this is a single entity. For some authors, catathrenia is a particular form of parasomnia; for others, it may be a variant of snoring or a respiratory problem. The goal is to establish whether or not catathrenia may be regarded as an expiratory vocal sound. An attempt was made to classify the origin of this sound according to its sound structure.
  
  
  METHODS
  We present the sound analysis of two patients, a man and a woman, with clinically diagnosed catathrenia and we compared them with the analysis of snoring. We use the spectrogram and the oscillogram. We classified the sounds according to the Yanagihara criteria.
  
  
  RESULTS
  The vocal nature of the sound was confirmed, and several significant differences to some snoring sounds were discovered. The analysis of the catathrenia samples demonstrated that these signals are type II according to Yanagihara classification; these signals had a very short jitter, and had formants and harmonics. However, snoring is a type III, very irregular and had formants but not harmonics.
  
  
  CONCLUSIONS
  The oscillogram and the spectrogram in these patients show that the origins of the sounds are clearly different: catathrenia is laryngeal, while snoring is guttural. Catathrenia cannot be considered as expiratory snoring.
authors.affiliation: Sleep Unit, University Clinic of Navarra, University of Navarra, Pamplona, Spain. jiriarte@unav.es
authors.forename: Jorge
authors.initials: J
authors.lastname: Iriarte
authors.forename: Secundino
authors.initials: S
authors.lastname: Fernández
authors.forename: Natalia
authors.initials: N
authors.lastname: Fernandez-Arrechea
authors.forename: Elena
authors.initials: E
authors.lastname: Urrestarazu
authors.forename: Inmaculada
authors.initials: I
authors.lastname: Pagola
authors.forename: Manuel
authors.initials: M
authors.lastname: Alegre
authors.forename: Julio
authors.initials: J
authors.lastname: Artieda
mesh_terms: D000368:Aged; D005260:Female; D006801:Humans; D007830:Larynx / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D009991:Oscillometry; D020447:Parasomnias / Q000175:diagnosis / Q000503:physiopathology*; D017286:Polysomnography; D012135:Respiratory Sounds / Q000503:physiopathology*; D020181:Sleep Apnea, Obstructive / Q000175:diagnosis* / Q000503:physiopathology*; D012894:Sleep Stages; D013018:Sound Spectrography