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.