title: Thyroarytenoid muscle activity associated with hypophonia in Parkinson disease and aging.
abstract: OBJECTIVE
  To compare electromyographic (EMG) amplitudes of the thyroarytenoid (TA) muscle in young and older individuals and individuals with idiopathic PD (IPD) under conditions of known vocal loudness (sound pressure level).
  
  
  BACKGROUND
  Voice disorders frequently accompany aging and IPD, but it is unclear how laryngeal muscle physiology is affected by these processes and how changes in laryngeal muscle activity result in characteristic changes of the voice.
  
  
  METHODS
  Absolute and relative (to maximum) EMG amplitudes of the TA muscle were compared during speech and nonspeech tasks. Corresponding sound pressure level (SPL) measures were obtained for the speech tasks.
  
  
  RESULTS
  Absolute TA amplitudes were consistently the highest in the young individuals, lowest in the individuals with IPD, and intermediate in the older individuals. Relative TA amplitudes were generally the highest for the young individuals, lowest for the older individuals, and intermediate for the individuals with IPD. SPL findings showed the older individuals and individuals with IPD produced most of the speech tasks with comparable SPLs, and these levels were consistently lower than those of the young individuals.
  
  
  CONCLUSIONS
  Reduced levels of TA muscle activity may contribute to the characteristic hypophonic voice disorders that frequently accompany IPD and aging.
authors.affiliation: Denver Center for the Performing Arts, Wilbur J. Gould Voice Research Center, CO 80204, USA.
authors.forename: K K
authors.initials: KK
authors.lastname: Baker
authors.forename: L O
authors.initials: LO
authors.lastname: Ramig
authors.forename: E S
authors.initials: ES
authors.lastname: Luschei
authors.forename: M E
authors.initials: ME
authors.lastname: Smith
mesh_terms: D000328:Adult; D000368:Aged; D000375:Aging / Q000502:physiology*; D004576:Electromyography; D005260:Female; D006801:Humans; D007821:Laryngeal Muscles / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D010300:Parkinson Disease / Q000150:complications / Q000503:physiopathology*; D013064:Speech Disorders / Q000209:etiology / Q000503:physiopathology; D014827:Vocal Cords / Q000503:physiopathology*; D014832:Voice Disorders / Q000209:etiology / Q000503:physiopathology*