Towards classroom acoustic standard in Korea considering occupied acoustic conditions

초록

This study aims to provide data for establishing acoustic standards in Korean school classrooms by analyzing the results of an acoustic survey conducted in 49 classrooms and lecture rooms across elementary, junior high, high schools, and universities, totaling 106 active classes. The findings indicate that in spaces where speech intelligibility is critical, acoustic design should not be limited to unoccupied room conditions but must incorporate occupied conditions reflecting students and teaching activities to ensure adequate speech intelligibility. Based on the acoustic measurement results of classrooms and lecture rooms, the recommended reverberation time for spaces with a volume of 250 m(3) or less is 0.60 s at 125 Hz-4 kHz, with a range of 0.48 s to 0.72 s depending on the number of people in the room. To enable teachers to maintain an appropriate Speech to Noise Ratio (SNR) value without unnecessarily raising their voice levels during class, the maximum noise level in an unoccupied room is L-Aeq <= 40 dBA (the air conditioner is running). To minimize noise from adjacent classrooms during class activities, the wall's sound insulation performance should be STC >= 50 for adjacent classrooms and STC >= 45 for adjacent corridors. In areas where speech privacy is important, such as in a combined wall with a corridor, the STC should be >= 50. To achieve a speech intelligibility of Speech Transmission Index (STI) >= 0.60 and U-50 >= 4.1 dB, the recommended SNR value of >= 15 dBA, and a C-50 of >= 4 dB should be met. In this study, only 5 % of the 106 classrooms were from special schools. Therefore, when establishing acoustic standards for educational facilities,it is necessary to consider not only general schools, but also special schools that require acoustic support.

키워드