Analysing the vocal behaviour of teachers during classroom teaching using a portable voice accumulator.

Purpose: Teachers are at a considerable risk of developing vocal health problems due to intensive voice use during teaching. This study investigated factors related to the teacher's voice during a teaching situation.

Methods: Overall, 113 teachers were recorded during a typical class lesson, lasting on average 48 min. A portable voice dosimeter (VoxLog System) was used to measure the sound pressure level (SPL) of the noise in the classroom, the teacher's voice SPL, the fundamental frequency (f) and the phonation time. General conditions of each lesson such as number of pupils, lesson subject and the educational level of the class were also collected. For the analysis, vocal loading doses and correlations between teacher's voice and noise SPL were calculated.

Results: Voice and noise SPL values varied across the lesson subjects, with highest levels measured in sports lessons. The mean noise SPL changed throughout a lesson with highest values at the beginning and at the end of the lessons. The correlation analysis of voice and noise SPL identified two groups of teachers with different vocal SPL behaviours. For some teachers, the voice SPL varied with the noise SPL. For others, voice SPL was constantly high. A regression model on the teacher's voice SPL yielded a strong correlation with f, the classroom noise SPL, and the individual vocal SPL behaviour.

Conclusions: Classroom noise SPL and individual vocal SPL behaviour were significantly associated with teachers' voice SPL during teaching. Addressing these factors could be important steps in reducing the vocal load in teachers.