Immediate Voice Changes Following Low- and High-Water Resistance Phonation in Healthy Adults: An Acoustic and...

The purpose of this study was to make a comparison between the short-term effects of low- and high-resistance water phonation exercises, adjusted using the DoctorVox® device, on acoustic parameters and voice self-perception in healthy adults.

Forty-seven healthy adults (37 females, 10 males) performed both low- and high-resistance exercises in a comparative experimental design. Low resistance was achieved with 3 cm of water in the DoctorVox® device, whereas high resistance was achieved by adjusting the DC-Valve® to a 3-mm opening at the same water depth. Acoustic voice recordings (fundamental frequency [F0], jitter, shimmer, harmonics-to-noise ratio [HNR], and acoustic voice quality index) and self-perception ratings (voice quality, phonatory comfort, and vocal fatigue) were collected at baseline, immediately post exercise, and 30 minutes post exercise. The analysis employed both parametric and nonparametric statistical tests.

The low-resistance condition resulted in a significant immediately post exercise increase in F0 and HNR, and a significant decrease in jitter; however, these effects largely disappeared by the 30-minute mark. In the high-resistance condition, only HNR demonstrated a significant change over time, but subsequent pairwise comparisons were not significant. The only significant difference between the two conditions was a higher HNR in favor of the high-resistance condition at 30 minutes post exercise. Despite the absence of any significant difference between the conditions in self-perception ratings, participants in both groups exhibited a tendency to report heightened voice quality and comfort, alongside diminished fatigue, subsequent to the exercises.

The findings suggest that low-resistance exercises may produce immediate acoustic trends in specific parameters and may be useful as a voice warm-up in healthy individuals. Although the effects of high-resistance exercises appear more limited, the results suggest a potential trend toward more sustained changes in certain acoustic parameters. This study highlights the importance of individualizing resistance levels in voice therapy based on specific goals and provides foundational data to guide clinical practice.