title: Reducing the negative vocal effects of superficial laryngeal dehydration with humidification.
abstract: OBJECTIVE
  Environmental humidification is a simple, cost-effective method believed to reduce superficial laryngeal drying. This study sought to validate this belief by investigating whether humidification treatment would reduce the negative effects of superficial laryngeal dehydration on phonation threshold pressure (PTP). Phonation threshold pressure data analysis may be vulnerable to bias because of lack of investigator blinding. Consequently, this study investigated the extent of PTP analysis reliability between unblinded and blinded investigators.
  
  
  METHODS
  Healthy male and female adults were assigned to a vocal fatigue (n = 20) or control group (n = 20) based on their responses to a questionnaire. PTP was assessed after 2 hours of mouth breathing in low humidity (dehydration challenge), following a 5-minute break in ambient humidity, and after 2 hours of mouth breathing in high humidity (humidification).
  
  
  RESULTS
  PTP significantly increased following the laryngeal dehydration challenge. After humidification, PTP returned toward baseline. These effects were observed in both subject groups. PTP measurements were highly correlated between the unblinded and blinded investigator.
  
  
  CONCLUSIONS
  Humidification may be an effective approach to decrease the detrimental voice effects of superficial laryngeal dehydration. These data lay the foundation for future investigations aimed at preventing and treating the negative voice changes associated with chronic, surface laryngeal drying.
authors.forename: Elizabeth Erickson
authors.initials: EE
authors.lastname: Levendoski
authors.forename: Anusha
authors.initials: A
authors.lastname: Sundarrajan
authors.forename: M Preeti
authors.initials: MP
authors.lastname: Sivasankar
mesh_terms: D000328:Adult; D016022:Case-Control Studies; D003681:Dehydration / Q000150:complications*; D005260:Female; D006801:Humans; D006813:Humidity; D007830:Larynx; D008297:Male; D015588:Observer Variation; D010699:Phonation / Q000502:physiology*; D011312:Pressure; D015203:Reproducibility of Results; D016037:Single-Blind Method; D016896:Treatment Outcome; D014832:Voice Disorders / Q000175:diagnosis / Q000209:etiology / Q000628:therapy*; D055815:Young Adult