title: The Effectiveness of Low-Level Light Therapy in Attenuating Vocal Fatigue.
abstract: OBJECTIVE
  Low-level light therapy (LLLT) is effective in reducing inflammation, promoting wound healing, and preventing tissue damage, but has not yet been studied in the treatment of voice disorders. The objective of this study was to investigate the possible effectiveness of LLLT in attenuating symptoms of vocal fatigue created by a vocal loading task as measured by acoustic, aerodynamic, and self-reported vocal effort.
  
  
  METHODS
  In a randomized, prospective study, 16 vocally healthy adults divided into four groups underwent a 1-hour vocal loading procedure, followed by infrared wavelength LLLT (828 nm), red wavelength LLLT (628 nm), heat, or no heat-light (control) treatment targeting the laryngeal region of the ventral neck surface. Phonation threshold pressure (PTP), relative fundamental frequency (RFF), and the inability to produce soft voice (IPSV) self-perceptual rating scale were recorded (1) at baseline, (2) immediately after vocal loading, (3) after treatment, and (4) 1 hour after treatment.
  
  
  RESULTS
  Vocal loading significantly increased PTP and IPSV and decreased onset and offset RFFs, consistent with a shift toward vocal dysfunction. Red light significantly normalized the combination of PTP, IPSV, and RFF measures compared to other conditions.
  
  
  CONCLUSIONS
  RFF is sensitive to a vocal loading task in conjunction with PTP and IPSV, and red LLLT may have a normalizing effect on objective and subjective measures of vocal fatigue. The results of this study lay the groundwork and rationale for future research to optimize LLLT wavelength combinations and overall dose.
authors.affiliation: MGH Institute of Health Professions, Charlestown Navy Yard, Boston, Massachusetts.
authors.forename: Loraine Sydney
authors.initials: LS
authors.lastname: Kagan
authors.affiliation: MGH Institute of Health Professions, Charlestown Navy Yard, Boston, Massachusetts; Massachusetts General Hospital Department of Surgery, Harvard Medical School, Boston, Massachusetts. Electronic address: James.Heaton@mgh.harvard.edu.
authors.forename: James T
authors.initials: JT
authors.lastname: Heaton
mesh_terms: D000162:Acoustics; D000328:Adult; D001900:Boston; D005260:Female; D006801:Humans; D007830:Larynx / Q000503:physiopathology / Q000528:radiation effects*; D028022:Low-Level Light Therapy; D008297:Male; D011446:Prospective Studies; D020127:Recovery of Function; D057566:Self Report; D012815:Signal Processing, Computer-Assisted; D013061:Speech Acoustics; D013067:Speech Perception; D013068:Speech Production Measurement; D013997:Time Factors; D016896:Treatment Outcome; D014832:Voice Disorders / Q000175:diagnosis / Q000503:physiopathology / Q000532:radiotherapy*; D014833:Voice Quality / Q000528:radiation effects*; D055815:Young Adult
keywords: Dysphonia; Low-level light therapy; Relative fundamental frequency; Vocal fatigue; Vocal hyperfunction