The Effects of Vocal Loading and Steam Inhalation on Acoustic, Aerodynamic and Vocal Tract Discomfort Measures in Adults

Abstract

<h2>Summary</h2><h3>Objectives</h3> This research investigated the effectiveness of a bespoke 20-minute Vocal Loading Task (VLT) in inducing changes in acoustic, aerodynamic, and vocal tract discomfort measures in vocally healthy adults. It also aimed to determine the effects of 10-minute steam inhalation and its potential effectiveness in reversing the detrimental effects of the VLT. <h3>Study design</h3> One-group pretest-posttest. <h3>Methods</h3> Forty-two vocally healthy adults (18-54 years) performed a 20-minute VLT. Participants read text aloud with higher vocal intensity (70-85 dB), a prosodic voice effect, and a forward head position. The VLT was followed by 10 minutes of steam inhalation over a basin of boiled water and a towel to contain the steam. Outcome measures were acoustic parameters (F₀, intensity, jitter, shimmer, noise-to-harmonics ratio, cepstral peak prominence), maximum phonation time, vocal tract discomfort (VTD), and self-reported effort and fatigue. These were collected at baseline (T0), immediately after VLT (T1), and immediately after steam inhalation (T2). <h3>Results</h3> At T1, there was a statistically significant increase in intensity (<i>P</i> = 0.009), number (<i>P</i> < 0.001) and severity (<i>P</i> < 0.001) of VTD sensations, increased effort (<i>P</i> < 0.001) and increased fatigue (<i>P</i> < 0.001). These measures decreased significantly at T2 and showed no statistical difference between T2 and T0. No significant effects for the remaining outcome measures were observed after either the VLT or the steam inhalation. <h3>Conclusion</h3> The bespoke VLT affected intensity, vocal tract discomfort, and self-perceived effort, and fatigue. This suggests that our short task successfully induced change to vocal tract parameters and may be useful for future research. There were positive effects on intensity, VTD, effort, and fatigue measures after 10 minutes of steam inhalation, reversing the effects of the VLT. This research suggests the potential effectiveness of steam inhalation as a simple and low-cost tool to address excess vocal intensity, vocal tract discomfort, effort, and fatigue.