Doctor of Philosophy (PhD)
Communication Sciences and Disorders
Objective: The current study examined the sensitivity of voice outcome measures in discriminating cut-off thresholds between degrees of dysphonia severity, correlations to perceived dysphonia, and the impact of vocal task. Differences between cases of adductor spasmodic dysphonia, benign vocal fold polyps, and unilateral vocal fold paralysis were also explored.
Method: Auditory-perceptual judgments were performed by three raters for four diagnostic groups: Normal (n=14), AdSD (n=15), Polyp (n=15) and UVFP (n=15). Receiver operator characteristic area under the curve (AUC) analyses established screening and dysphonia severity (mild, moderate, severe) cut-off thresholds for auditory-perceptual visual analog scale (VAS) ratings and acoustic measures (f0_SD, CPP, CPP_SD, CSID, H1*-H2*) for connected speech and vowel /i/, and glottal area waveform (GAW) high-speed videoendoscopic measures (f0_SD, H1-H2, open quotient, harmonic-to-noise ratio, harmonic richness factor, maximum declination rate, amplitude quotient, and relative glottal gap) for the vowel /i/. Odds ratios calculated the likelihood of outcome measures to increase degrees of dysphonia severity, and which voice disorders were more likely to have increased or decreased dysphonia compared to each other.
Results: Auditory-perceptual and acoustic cut-off thresholds were established for screening dysphonia and across degrees of dysphonia severity. Significant odds ratios were found for VAS, CPP and CSID. HSV measures had lower correlations (rs=s=0.6-0.8). Vocal task did not influence rater agreement, and connected speech did not show better sensitivity and specificity in establishing dysphonia severity thresholds over sustained vowel /i/. No significant differences were found between connected speech and sustained phonation for spasmodic dysphonia. Only high-speed harmonic GAW measures showed significant differences between disordered groups (AdSD and UVFP for H1-H2 and harmonic richness factor).
Conclusion: VAS and CSID were most robust in measuring dysphonia across vocal tasks. Contrary to expectations, findings did not show task specific differences for spasmodic dysphonia. Between AdSD, Polyps, and UVFP, no significant differences were found for auditory-perceptual and acoustic measures, but differences did emerge between GAW measures. Results varied between which high-speed measures discriminated moderate/severe dysphonia, which showed correlations to auditory-perceptual judgments, and/or differentiated between voice disorders.
Parker, Lindsey Ann, "Defining Change Beyond a Binary System: Measurement and Interpretation of Degrees of Dysphonia Severity in the Individual and Across Voice Disorders" (2022). LSU Doctoral Dissertations. 5986.
Available for download on Monday, November 03, 2025