Effects of a Short-Term Vocal Loading Task and Different Restoration Strategies on Voice

Objective: The purpose of this study is to examine the effects of a short-term (30 minutes) vocal loading task (VLT) on the objective and subjective parameters of voice and determine the restorative strategies of three different vocal exercises performed after the VLT.

Methods: The sample of the study included 30 normophonic women. The protocols that were applied in the study were carried out on three consecutive days. In each protocol, right after the VLT based on 30 minutes of phonation at 80-85 dBA_{30 cm}, a randomly selected strategy from among the three different therapeutic strategies was performed for 10 minutes. The therapeutic strategies consisted of the water resistance therapy (tube submerged depth 3-cm) (WRT protocol), the voiced oral high-frequency oscillation (VOHFO) technique performed using the Acapella Duet (Smith Medical, USA) (VOHFO protocol), and the semi-occluded nasal tract exercise (SONTE) (SONTE protocol). The analyses were conducted based on acoustic, electroglottographic, and perceived vocal exertion (Borg CR-100) measurements made at different time points.

Results: After the VLT, increased fundamental frequency (F_o) and cepstral peak prominence (CPP) values, and decreased electroglottography (EGG)-contact quotient (CQ) and nasalance score values were observed. In comparison to the values measured before the performance of the exercises, during all three exercises, EGG-CQ values decreased, and EGG-average (Avg.) jitter values increased. Among the three included exercises, the lowest Borg CR-100 scores were obtained after the SONTE protocol. Only the EGG-CQ values obtained after the SONTE and VOHFO protocols were lower than those obtained after the VLT.

Conclusions: The short-term (30 minutes) VLT (80-85 dBA_{30 cm}) performed in this study led to differences in the subjective and objective parameters that were measured, and it was considered to be an effective VLT. All three exercises that were used immediately after the VLT as restoration strategies were observed to be effective in reducing perceptual vocal effort scores, and similar vocal fold movement patterns were observed during the exercises according to the EGG results. According to the increased acoustic-CPP and reduced EGG-CQ and EGG-Avg. jitter parameter values after the exercises, the SONTE and VOHFO protocols were more successful than the WRT protocol in stabilising the negative effects of vocal loading.