Water Resistance Therapy in Individuals with Parkinson's Disease: A Session-by-Session Analysis of the Vocal Quality.

Objectives: Verify session-by-session effects of the water resistance therapy (WRT) on the vocal quality of individuals with Parkinson's disease (PD).
Methods: This is a retrospective analytical study. Then, the samples were acquired from a database composed of 10 men aged between 50 and 90 years old diagnosed with PD. The participants underwent WRT with a resonance tube; then, they were guided to perform the following phonatory tasks: comfortable pitch and loudness, high pitch, low pitch, ascending and descending glissandos, and sentence uttering. Furthermore, tube depth ranged from 2 cm to 9 cm. Finally, WRT was implemented twice per week, totaling eight sessions, each lasting 45 minutes. Participants were assessed before and after each therapy session. Hence, the data were assessed with spectrographic analysis, vocal intensity, cepstral peak prominence-smoothed, alpha ratio, L1-L0, oscillatory frequency, and auditory-perceptual assessment of overall degree, roughness, breathiness, and instability. One-way repeated measures analysis of variance and Friedman tests were applied (P < 0.05). Furthermore, Holm-Sidak and Tukey tests were used as posthoc tests.
Results: After the sixth session, the spectrographic analysis revealed that the tracing color intensity of medium frequencies darkened, whereas a better result could be observed after the eighth session. Regarding vocal intensity, the improvement could be observed from the third session. Additionally, L1-L0 followed the same results. The overall degree auditory-perceptual assessment revealed the best results only after the second, third, and fourth sessions; however, after the eighth session, the instability increased.
Conclusions: WRT allowed better results from the third session, with some improvements in the sixth session. However, the instability increased after the eighth session; thus, it is important to review the phonatory tasks and session numbers to avoid an overload in the phonatory system.
Competing Interests: Declaration of Competing Interest None.
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