Vocal impact of a prolonged reading task in dysphonic versus normophonic female teachers

This study evaluates the effect of a 2-hour reading task between 70 and 75 dB(A) in 16 normophonic and 16 dysphonic female teachers with vocal nodules.

Objective measurements (acoustic analysis, voice range measurements, and aerodynamic measurements) and subjective self-ratings were collected before and every 30 minutes during the reading to determine the voice evolution in both groups.

Fundamental frequency, lowest frequency, highest frequency (F-High), highest intensity, and intensity range increase through the reading, whereas shimmer decreases. Maximum phonation time decreases after 30 minutes. Estimated subglottal pressure (ESP) and sound pressure level increase during the first hour. Afterward, ESP decreases. Self-ratings worsen through time. When comparing the normophonic and the dysphonic teachers, self-ratings reveal more complaints in the dysphonic group. Few differences in objective measurements are found between both groups: normophonic teachers show lower ESP, higher F-High, and greater frequency range.

Frequency modifications from acoustic analysis and voice range measurements suggest an increased laryngeal tension during vocal load, while subjects perceive a worsening of voice. Aerodynamic parameters depict first a deterioration of voice efficiency and then an adaptation to the prolonged reading. The comparison between both groups shows a discrepancy between objective measurements and self-ratings, suggesting that both approaches are necessary to have a complete view of vocal load effects. Surprisingly, both groups behave similarly through vocal load, without more or quicker deterioration of voice in the dysphonic group.