Voice Impact of a Prolonged Reading Task at Two Intensity Levels: Subjective Self-Ratings

Objectives: The objectives of this study are to evaluate the impact on voice of both duration and intensity level of 2 hours of continuous oral reading, using subjective self-ratings.
Methods: Fifty normophonic women undergo two sessions of voice loading in which the required intensity level of voice varied: 60-65 dB(A) for the first session, and 70-75 dB(A) for the second session. Voice intensity level is constantly controlled with a Digital Sound Level Meter at a distance of 40cm from the mouth. Subjects’ voices are orally loaded by reading a novel of their choice for 2 hours in a quiet room (background level < 30dBA). The effects of loading are assessed with regard to self-ratings of voice obtained before and every 30 minutes during the loading tasks. The following parameters are evaluated using a 100-mm horizontal visual analogue scale: voice quality, phonation effort, vocal fatigue and laryngeal discomfort. A repeated-measure analysis of variance (ANOVA Duration X Intensity Level) where the subjects are used as their own controls is carried out to compare data obtained at different times of the reading sessions.
Results and conclusion: There is a significant effect of the duration (p < 0.0001) for all the subjective self-ratings, but no differences between the two intensity levels of reading. Feeling of phonation effort, vocal fatigue and laryngeal discomfort significantly increase during prolonged reading, whereas self-rating of voice quality decrease. Subjects do not report more complaints in the 70-75 dB session than in the 60-65 dB one. To conclude, subjects’ self-ratings of voice significantly worsens throughout the reading task as a duration effect, but there is no intensity level effect.