title: Reliability of clinical office-based laryngeal electromyography in vocally healthy adults.
abstract: OBJECTIVE
  This study aimed to conduct a 3-session reliability assessment of the laryngeal electromyography (LEMG) signal in healthy participants during intensity controlled vocalization tasks. We hypothesized that vocal intensity level and testing session would affect LEMG measures.
  
  
  METHODS
  This prospective study used a 2-factor repeated measures design. Seven participants underwent bipolar needle LEMG of the right thyroarytenoid muscle. Data were collected over 3 testing sessions using vocalization tasks performed with visually guided intensity feedback targets (65 and 75 dB SPL). Root mean square amplitudes in microvolts were analyzed for within-session and between-session reliability.
  
  
  RESULTS
  The main effect for intensity was found to approach significance (F = 5.71, P = .054). However, intraclass correlation coefficients (ICCs) using a 2-factor mixed random effect model indicated poor to fair signal reliability between testing sessions (ICC = 0.56 at 65 dB, 0.40 at 70 dB). Intraclass correlation coefficients for within-session data indicated excellent reliability for all testing conditions (0.84-0.98).
  
  
  CONCLUSIONS
  Using a quantitative analysis protocol to inform an essentially qualitative technique, our results indicated that there was generally poor to fair reliability in the LEMG signal over testing sessions. Vocal intensity was an important variable that affected LEMG signal reliability. Standardization of LEMG protocols using vocal control parameters and quantitative analyses may help improve LEMG reliability in clinical settings.
authors.affiliation: College of Health Sciences, University of Kentucky, Lexington, Kentucky, USA.
authors.forename: Daniel J
authors.initials: DJ
authors.lastname: Croake
authors.forename: Joseph C
authors.initials: JC
authors.lastname: Stemple
authors.forename: Timothy
authors.initials: T
authors.lastname: Uhl
authors.forename: Sanford
authors.initials: S
authors.lastname: Archer
authors.forename: Richard D
authors.initials: RD
authors.lastname: Andreatta
mesh_terms: D000293:Adolescent; D000328:Adult; D000553:Ambulatory Care; D004576:Electromyography; D005260:Female; D006801:Humans; D007821:Laryngeal Muscles / Q000502:physiology; D007830:Larynx / Q000502:physiology*; D008297:Male; D009819:Office Visits; D011446:Prospective Studies; D012016:Reference Values; D015203:Reproducibility of Results; D014831:Voice / Q000502:physiology*; D055815:Young Adult
keywords: LEMG; motor units; neuromuscular; thyroarytenoid