title: Effect of level of presentation to listeners on scaled speech intelligibility of speakers with dysarthria.
abstract: OBJECTIVE
  This study examined the effect of intensity level of presentation on scaling of speech intelligibility in speakers with and without dysarthria.
  
  
  METHODS
  A total of 50 utterances produced by speakers with dysarthria and healthy speakers were played to 60 listeners in four conditions, which consisted of two different presentation levels (‘high’ vs. ‘low’) and equalization of levels across utterances (‘adjusted’ vs. ‘unadjusted’). Speech intelligibility was scaled by using a direct magnitude estimation technique with and without modulus.
  
  
  RESULTS
  A significant decrease in speech intelligibility was indicated when the stimuli were adjusted to have fixed intensity on the most intense vocalic nuclei of each word, while no significant change was found between ‘high’ and ‘low’ presentation level conditions.
  
  
  CONCLUSIONS
  The findings suggest that an increase in presentation level alone does not result in significant improvement in speech intelligibility ratings. The results are discussed by considering clinical implications in conducting speech therapy with emphasis on intensity variation.
authors.affiliation: Department of Communication Sciences and Disorders, Louisiana State University, Baton Rouge, LA, USA.
authors.forename: Yunjung
authors.initials: Y
authors.lastname: Kim
authors.forename: Christina
authors.initials: C
authors.lastname: Kuo
mesh_terms: D000328:Adult; D004401:Dysarthria / Q000209:etiology / Q000523:psychology*; D006801:Humans; D008144:Loudness Perception; D019578:Multiple System Atrophy / Q000150:complications; D015588:Observer Variation; D010300:Parkinson Disease / Q000150:complications; D013065:Speech Intelligibility; D020521:Stroke / Q000150:complications; D014833:Voice Quality; D055815:Young Adult