Assessment of indoor ambient noise level in school classrooms

Previous studies have shown that poor acoustic conditions inside classrooms interfere with an optimal teaching-learning process. Since high background noise levels and long reverberation times cause higher vocal use among teachers, and lower understanding among students, it is recommended to guarantee physical conditions inside the classrooms that ensure optimal conditions for teaching and learning. To reach this goal, it is important to characterize and control two main factors, namely reverberation and noise. This work focuses on measurement and analysis procedures of indoor ambient noise level during primary school classroom activities, with the main objective to optimize the measurement procedure (data acquisition and elaboration) of background noise in real environments. The presented noise levels were measured in three classrooms in a primary school in Torino (before and after acoustical treatment). They were monitored for the entire duration of classroom activities by positioning a sound level meter near to the teacher’s desk, at least one meter far from every surface. From every long-term measurements (LTMs), short-term measurements (STMs) of one, five and 15 minutes were extracted randomly. LTMs and STMs were elaborated in terms of A-weighted equivalent sound pressure level (LAeq) and of A-weighted statistical sound pressure level (LA90 that corresponds to the level which is overtaken for the 90% of the measurement duration). After every monitored activity teachers filled in a questionnaire on work-related conditions. Associations between self-reports and objective LTMs and STMs of noise during teaching hours were determined using Generalized Estimating Equations (GEEs).