Objective. The aim of this study was to describe the effect of superficial hydration, with or without, systemic hydration on the vocal quality of female professional singers. Professional voice users exhibit the highest prevalence of voice disorders due to high vocal demands. Previous studies have mainly focused on PTP and PPE when superficial hydration was applied to singers. Thus, the current study focused on vocal quality changes by examining acoustic, perceptual measures and vocal fatigue.
Study design.
A within-subject, experimental, two group comparative, pre-test post-test research design was applied where professional singers between the ages of 18-32 acted as their own control.
Methods. The study replicated the protocol, as executed by van Wyk et al., (2016) with some additions. These additions included the experimental conditions of superficial hydration and combined superficial and systemic hydration and their effects on voice quality in female professional singers. Participants also completed the Vocal Fatigue Index (VFI) in addition to the voice protocol. Pre- and post-test perceptual and acoustic voice assessments were conducted for each participant on two occasions (1) a control test with no applied hydration and (2) a experimental test where participants were randomly divided into a superfical hydration group or a combined systemic and superficial hydration group.
Results. When comparing pre- and posttest results a statistical significant increase in MPT values were obtained for the hypohydrated (p=0,015) and superficial hydration (p=0,004) condition. Furthermore, a significant increase in frequency min (Hz) (p=0.019) within the hypohydrated condition was also observed. Within the combined hydration condition, a significant increase was observed in the intensity (dB) min (p=0.010) and F_0(Hz) min (p=0.002) scores. Between-group, posttest comparison outcomes revealed that where superficial hydration was applied mean shimmer % (p=0.016), MPT (sec) (p=0.003), and dysphonia severity index (DSI) (p=0.020) scores increased significantly and a significant reduction in mean intensity (dB) max (p=0.049) and intensity (dB) min (p=0.018) was observed.
Conclusion. In this study, it was confirmed that the use of superficial hydration had positive outcomes on the perceptual parameters of voice quality and vocal fatigue in female professional singers. Mixed results were however found regarding the acoustic parameters of voice. The positive results obtained pertaining to perceptual voice quality and vocal fatigue, can be used as a potential preventative measure in vocal hygiene programs.
Key Words: Female Professional Singers; Phonotrauma; Superficial Hydration; Vocal Fatigue; Systemic Hydration; Vocal Hygiene.