Elementary classroom acoustics: what really matters

This work answer the question on what are the optimal acoustic conditions for speech communication and learning in classroom. In order to do this, a simple protocol to carry out measurements to characterize classroom acoustics is provided and the thresholds of the main parameters to guarantee an adequate sound environment for educational facilities have been identified. In 29 first-grade classrooms, background noise level in silence and during group activities, reverberation time also in unoccupied conditions, speech clarity, ratio of useful to detrimental energy and speech signal were acquired along the main axis. Correlation analyses allowed for the selection of reverberation time or speech clarity in the central position as the essential parameters to evaluate the acoustical quality of classrooms, which were clustered either in bad or good acoustic group based on the cluster analysis. The thresholds for the reverberation time and speech clarity in the central position are 0.8 s and 2.6 dB, respectively. Further investigations were performed on the early, late and total components of the sound strength parameter.