[Influence of classrooms acoustics on the teachers' voice sound pressure level]

Despite recent decreases in the number of registered cases of chronic disease of vocal mechanism, this disorder is still at the forefront of all occupational diseases in Poland. Most of the cases are observed in the Section of Education. Acoustic conditions in classrooms are often thought to be one of the causes of voice disorders. The aim of this study was to examine how the acoustics of classrooms affects the sound pressure of teachers' voice.

The acoustic properties of 21 classrooms in primary schools were studied as regards the working conditions of teachers' voice. The classrooms were divided into two groups: classes 0-III and classes IV-VI. Measurements of acoustic properties were performed according to PN-EN ISO 3382-1:2009, and measurements of sound pressure levels in the classrooms according to the Hodgson method. To study the relationship between the variables Spearman's rank correlation analysis was used.

The study revealed a statistically significant relationship between the classroom acoustics and the students' activity (correlation coefficient, 0.86). It was also shown that the students' activity directly affected the level of teachers' voice (correlation coefficient, 0.68). In only 24% of classrooms SPL of teachers' voice corresponded with the level of normal speech.

The SPL of teachers' voice is influenced by a number of factors, including background noise and indirectly the classroom acoustics. One of the possibilities to improve working conditions of teachers is to create a suitable acoustic climate in the workplace, through acoustic treatment or changing equipment.