Water Resistance Therapy in Individuals with Parkinson’s Disease: Session-by-Session Spectrographic Analysis

Objective: To analyze the effects of Water Resistance Therapy (WRT), session by session, on the spectrographic parameters of individuals with Parkinson’s Disease (PD).

Methods: Data from 10 male individuals diagnosed with PD, exhibiting hypokinetic dysarthria, and scoring above 21 on the Montreal Cognitive Assessment protocol were analyzed. The WRT consisted of eight sessions, occurring twice a week and lasting 50 minutes each. The vowel /a/ was recorded at habitual pitch before and after each therapy session. Spectrographic analysis was conducted using Praat software (6.0.52) with a window length of 0.05s, time step of 0.002s, frequency step of 5Hz, maximum frequency of 5000Hz, and Hamming window shape. The parameters evaluated were “tracing color intensity”, “presence of noise”, “definition and regularity of the harmonics”, and “presence of subharmonics”. Two judges assessed these parameters using a 100-mm visual analog scale, the final score was the mean of their values. For “tracing color intensity” and the “presence of noise”, the analysis was based on frequency ranges (low 3000Hz). Repeated measures ANOVA was applied for variables with parametric distribution and the Friedman Test for those with non-parametric distribution (p<0.05).

Results: The variable “tracing color intensity” showed a difference (p=0.001) in medium frequencies. The range became darkened from the sixth session, with a better result in the eighth session. The intensity of color in the spectrographic analysis can indicate the distribution of acoustic energy in the vocal tract (vocal projection). During the sessions, exercises were performed with variations in vocal intensity and the depth of the tube in the water. These phonatory tasks may have contributed to improved intrinsic muscle tonus, promoting better glottal closure and, subsequently, increased subglottic pressure. This improvement was reflected in the more intense color of the spectrogram.

Conclusions: The WRT demonstrated a positive effect on the intensity of color in the spectrogram in medium frequencies in individuals with PD, starting from the sixth therapy session, indicating enhanced vocal projection.