Meike Brockmann-Bauser

Acoustic Perturbation Measures Improve with Increasing Vocal Intensity in Individuals With and Without Voice Disorders

OBJECTIVE In vocally healthy children and adults, speaking voice loudness differences can significantly confound acoustic perturbation measurements. This study examines the effects of voice sound pressure level (SPL) on jitter, shimmer, and harmonics-to-noise ratio (HNR) in adults with voice disorders and a control group with normal vocal status. STUDY DESIGN This is a matched case-control study. METHODS We assessed 58 adult female voice patients matched according to approximate age and occupation with 58 vocally healthy women. Diagnoses included vocal fold nodules (n = 39, 67.2%), polyps (n = 5, 8.6%), and muscle tension dysphonia (n = 14, 24.1%). All participants sustained the vowel /a/ at soft, comfortable, and loud phonation levels. Acoustic voice SPL, jitter, shimmer, and HNR were computed using Praat. The effects of loudness condition, voice SPL, pathology, differential diagnosis, age, and professional voice use level on acoustic perturbation measures were assessed using linear mixed models and Wilcoxon signed rank tests. RESULTS In both patient and normative control groups, increasing voice SPL correlated significantly (P < 0.001) with decreased jitter and shimmer, and increased HNR. Voice pathology and differential diagnosis were not linked to systematically higher jitter and shimmer. HNR levels, however, were statistically higher in the patient group than in the control group at comfortable phonation levels. Professional voice use level had a significant effect (P < 0.05) on jitter, shimmer, and HNR. CONCLUSIONS The clinical value of acoustic jitter, shimmer, and HNR may be limited if speaking voice SPL and professional voice use level effects are not controlled for. Future studies are warranted to investigate whether perturbation measures are useful clinical outcome metrics when controlling for these effects.

Do standard instrumental acoustic, perceptual, and subjective voice outcomes indicate therapy success in patients with functional dysphonia?

OBJECTIVES The validity and sensitivity to change of instrumental acoustic measurements in patients with functional dysphonia have been controversially discussed. This work examines combined voice therapy effects on standard acoustic measurements, and if these agree with perceptual and subjective voice outcomes. STUDY DESIGN Retrospective study. METHODS Thirty-nine patients (26 women, 13 men) aged 20-70 years (mean: 46.3, standard deviation 12.8) with functional dysphonia were investigated before and after combined voice therapy. Instrumental parameters included mean and range of speaking fundamental frequency (fo) and intensity (SPL (dBA)); maximum SPL and mean fo of calling voice; minimum, maximum, range of singing voice fo and SPL, jitter (%), and the Dysphonia Severity Index. Voice Handicap Index-9 international was used for subjective and Grading-Roughness-Breathiness-Asthenia-Strain scale for perceptual assessment. Differences were investigated by Wilcoxon signed ranks test and coherences by Spearman rank correlation coefficient. RESULTS After treatment, the speaking voice fo range (7-8.13 semitones) and SPL range (12.9-14.85 dB(A)) were significantly larger (P < 0.05). Both parameters were highly correlated (P < 0.001). Subjective symptoms were significantly reduced from a mean Voice Handicap Index-9 international of 15.6-8.6, and all perceptual Grading-Roughness-Breathiness-Asthenia-Strain scale parameters were significantly improved (G: 1.05-0.51) after therapy (P < 0.05). These findings were not associated with any acoustic parameter (P > 0.05). CONCLUSIONS Significantly improved subjective and perceptual findings verify positive combined voice therapy effects in patients with functional dysphonia. The larger fo and SPL speaking voice range after treatment indicate an altered voice technique. These instrumental measures may be clinical indicators of therapy success and transfer effects.