title: Nonlinear dynamic-based analysis of severe dysphonia in patients with vocal fold scar and sulcus vocalis.
abstract: OBJECTIVE
  The primary goal of this study was to evaluate a nonlinear dynamic approach to the acoustic analysis of dysphonia associated with vocal fold scar and sulcus vocalis.
  
  
  METHODS
  Case-control study.
  
  
  METHODS
  Acoustic voice samples from scar/sulcus patients and age-/sex-matched controls were analyzed using correlation dimension (D2) and phase plots, time-domain based perturbation indices (jitter, shimmer, signal-to-noise ratio [SNR]), and an auditory-perceptual rating scheme. Signal typing was performed to identify samples with bifurcations and aperiodicity.
  
  
  RESULTS
  Type 2 and 3 acoustic signals were highly represented in the scar/sulcus patient group. When data were analyzed irrespective of signal type, all perceptual and acoustic indices successfully distinguished scar/sulcus patients from controls. Removal of type 2 and 3 signals eliminated the previously identified differences between experimental groups for all acoustic indices except D2. The strongest perceptual-acoustic correlation in our data set was observed for SNR and the weakest correlation was observed for D2.
  
  
  CONCLUSIONS
  These findings suggest that D2 is inferior to time-domain based perturbation measures for the analysis of dysphonia associated with scar/sulcus; however, time-domain based algorithms are inherently susceptible to inflation under highly aperiodic (ie, type 2 and 3) signal conditions. Auditory-perceptual analysis, unhindered by signal aperiodicity, is therefore a robust strategy for distinguishing scar/sulcus patient voices from normal voices. Future acoustic analysis research in this area should consider alternative (e.g., frequency- and quefrency-domain based) measures alongside additional nonlinear approaches.
authors.affiliation: Department of Audiology and Speech-Language Pathology, Catholic University of Daegu, Gyeongsan, Korea.
authors.forename: Seong Hee
authors.initials: SH
authors.lastname: Choi
authors.forename: Yu
authors.initials: Y
authors.lastname: Zhang
authors.forename: Jack J
authors.initials: JJ
authors.lastname: Jiang
authors.forename: Diane M
authors.initials: DM
authors.lastname: Bless
authors.forename: Nathan V
authors.initials: NV
authors.lastname: Welham
mesh_terms: D000368:Aged; D001307:Auditory Perception; D016022:Case-Control Studies; D002921:Cicatrix / Q000473:pathology / Q000503:physiopathology*; D055154:Dysphonia / Q000473:pathology / Q000503:physiopathology*; D006801:Humans; D008875:Middle Aged; D017711:Nonlinear Dynamics; D010699:Phonation; D012720:Severity of Illness Index; D013018:Sound Spectrography; D013061:Speech Acoustics; D013068:Speech Production Measurement; D013997:Time Factors; D014827:Vocal Cords / Q000473:pathology / Q000503:physiopathology*; D014833:Voice Quality