Fundamental frequency, sound pressure level and vocal dose of a vocal loading test in comparison to a real teaching situation.

Vocal loading capacity is an important aspect of vocal health, especially for people in vocally demanding occupations such as teaching. To analyze vocal loading, vocal loading tests (VLTs) or portable voice devices such as accelerometers have been used. However, it remains unclear how much a VLT in a clinical setup reflects the vocal effort of a real situation, in particular for teachers in a given classroom lesson. In this study of vocally healthy 101 student teachers, we analyzed different vocal doses for a 10-min VLT (80 dB at a distance of 30 cm) and a real 45-min teaching lesson. The phonation time, fundamental frequency, sound pressure level, and noise level were recorded using the VoxLog accelerometer/microphone system for both conditions. From these measurements the time dose, cycle dose, distance dose, energy dissipation dose, and radiated energy dose were calculated. The VLT was associated with a higher fundamental frequency, a higher sound pressure level, and higher relative phonation time compared to the real teaching lesson. Nevertheless, most vocal doses did not differ significantly between the conditions. A VLT of 10 min with >80 dB at 30 cm distance shows only small differences of vocal doses in comparison to a real teaching situation of 45 min. Thus, for clinical vocal assessment the vocal load of a VLT can be related to an approximately 45-min teaching situation.