On-Site Sound Pressure Level Evaluation of Emergency Broadcasting Systems in University Buildings

Korean regulations for emergency broadcasting systems specify only the rated power output of loudspeakers: 1 W for indoor and 3 W for outdoor applications. However, they do not provide quantitative sound pressure level (SPL) criteria. In this study, A-weighted SPLs in nine buildings at a university were measured and analyzed by reproducing actual emergency broadcast signals. The measured SPLs ranged from 51 dB (A) to 99 dB (A), indicating a difference of approximately 20 dB (A) between the lowest and highest average values across the buildings. In addition, the alarm tone exhibited SPLs approximately 20 dB (A) higher than those of the voice message, representing a perceptual loudness difference exceeding fourfold. These results confirm that despite the installation of emergency broadcasting systems adhering to power-based criteria, the loudness experienced by occupants can vary substantially depending on the spatial characteristics and specific measurement zones within buildings. Consequently, regulatory provisions based solely on loudspeaker power output are inadequate for ensuring consistent audibility in emergency broadcasts. This indicates the need for quantitative SPL criteria to ensure adequate occupant perception performance.