title: Long-time average spectrum in individuals with Parkinson disease.
abstract: BACKGROUND
  Various methods of acoustic analysis have been used to describe phonatory deficits in Parkinson disease (PD), including long-time average spectrum (LTAS) analysis.
  
  
  OBJECTIVE
  The aim of this study was to utilize the LTAS to investigate laryngeal deficits in individuals with PD.
  
  
  METHODS
  Twenty-eight individuals with idiopathic PD and 10 controls were participants for this study. An LTAS was generated from a standard reading sample and analyzed using the following measurements: Mean spectral energy (MSE), first spectral peak, spectral tilt (ST), three spectral slope (SS) measures (i.e., SSF0-1kHz, SS1-5kHz, and SS ratio) and four spectral moments (mean, standard deviation, skewness, and kurtosis).
  
  
  RESULTS
  Individuals with PD were found to demonstrate significantly lower MSE, spectral mean and spectral SD, along with higher spectral skewness compared to control speakers. Furthermore, ST was positively correlated with self-rated symptom severity and self-rated medication effectiveness for individuals with PD.
  
  
  CONCLUSIONS
  The LTAS findings were consistent with either reduced vocal fold adduction or vocal fold bowing in individuals with PD compared to control speakers. Additionally, vocal fold adductory changes were one possible explanation for correlations between LTAS and self-ratings of medication effectiveness and disease severity.
authors.affiliation: Department of Communication Sciences and Disorders, Bowling Green State University, Bowling Green, OH, USA.
authors.forename: Lindsey K
authors.initials: LK
authors.lastname: Smith
authors.affiliation: Department of Communication Sciences and Disorders, Bowling Green State University, Bowling Green, OH, USA.
authors.forename: Alexander M
authors.initials: AM
authors.lastname: Goberman
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010300:Parkinson Disease / Q000175:diagnosis* / Q000503:physiopathology; D010699:Phonation / Q000502:physiology; D013061:Speech Acoustics; D013997:Time Factors; D014833:Voice Quality / Q000502:physiology
keywords: LTAS; Parkinson disease; long-time average spectrum; phonation; voice