title: Residual signal auto-correlation to evaluate speech in Parkinson's disease patients.
abstract: OBJECTIVE
  To evaluate the maximum residual signal auto-correlation also known as pitch amplitude (PA) values in patients with Parkinson's disease (PD) patients.
  
  
  METHODS
  The signals of 21 Parkinson's patients were compared with 15 healthy individuals, divided according age and gender.
  
  
  RESULTS
  Statistical difference was seen between groups for PA, 0.39 for controls and 0.25 for PD. Normal value threshold was set as 0.3; (p<0.001). In the Parkinson's group 80.77%, and in the control group only 12.28%, had a PA<0.3 demonstrating an association between these variables. The dispersion diagram for age and PA for PD individuals showed p=0.01 and r=0.54. There was no significant difference in relation to gender and PA between groups.
  
  
  CONCLUSIONS
  The significant differences in pitchs amplitude between PD patients and healthy individuals demonstrate the methods specificity. The results showed the need of prospective controlled studies to improve the use and indications of residual signal auto-correlation to evaluate speech in PD patients.
authors.affiliation: School of Engineering of São Carlos, University of São Paulo.
authors.forename: José Carlos
authors.initials: JC
authors.lastname: Pereira
authors.forename: Arthur Oscar
authors.initials: AO
authors.lastname: Schelp
authors.forename: Arlindo Neto
authors.initials: AN
authors.lastname: Montagnoli
authors.forename: Ana Rita
authors.initials: AR
authors.lastname: Gatto
authors.forename: André Augusto
authors.initials: AA
authors.lastname: Spadotto
authors.forename: Lídia Raquel
authors.initials: LR
authors.lastname: de Carvalho
mesh_terms: D000328:Adult; D016022:Case-Control Studies; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010300:Parkinson Disease / Q000150:complications / Q000503:physiopathology*; D010699:Phonation / Q000502:physiology*; D012680:Sensitivity and Specificity; D013018:Sound Spectrography; D013061:Speech Acoustics; D013064:Speech Disorders / Q000175:diagnosis* / Q000209:etiology / Q000503:physiopathology; D013067:Speech Perception / Q000502:physiology; D013068:Speech Production Measurement; D014833:Voice Quality