Voice characteristics and recovery patterns in Indian adult males after vocal loading

Abstract

The study aimed to measure the effects of vocal loading on voice characteristics in Indian adult males, to document complaints associated with vocal fatigue and to monitor recovery patterns of voice after the vocal loading task. Twenty adult males between the ages of 18 and 30 years participated in this study. The subjects were instructed to read a book at 75-80 dB SPL up to an hour or until they reported themselves as fatigued. Pre and post experiment voice assessments were carried out using GRBAS scale and MDVP analysis. The duration of prolonged reading and signs of vocal fatigue were documented. Voice recovery was tracked at 5, 10, 15, 20 minutes and 24 hours following the immediate post experiment. Paired t test and repeated measure of analysis of variance (ANOVA) were used for statistical analysis. Overall quality of voice change (Grade) was more pronounced after vocal loading. Significant reduction (around 6 seconds) in maximum phonation time and a significant increase in S/Z ratio were found. MDVP analysis revealed significant decrease in lowest fundamental frequency and increase in phonatory fundamental frequency range, short and long term frequency and amplitude measurements, noise and voice irregularity related measures after vocal loading. Initial signs of fatigue such as throat pain, throat tightness and running out of breath were noticed as early as 15 minutes and subjects were able to sustain the task for not more than 30 minutes. Short and long term frequency and amplitude measures and noise to harmonics ratio revealed a significant recovery pattern. Complaints of vocal fatigue, voice symptoms, and vocal recovery after vocal loading can be tracked and monitored using perceptual and acoustic measures. These findings can be applied to understand vocal endurance, susceptibility to vocal fatigue and physiological changes due to vocal loading.