실제 강의현장에서의 음성과 소음 레벨을 반영한 음성 명료도 지표의 측정 및 평가

초록

The useful-to-detrimental sound ratios (U50) measure can be more practically useful means of assessing and understanding real classroom situations because it can be easily obtained from both measured clarity (C50) and signal-to-noise-ratio (SNR) values in classrooms during speech communication. The goal of this work is to better understand room acoustics conditions for real speech communication during actual lectures and to provide U50 values for achieving ‘good’ acoustical conditions for speech intelligibility in university classrooms. In the present work, U50 is determined from both measured C50 and SNR values during 15 actual lectures in 11 university classrooms in Korea. The linear regression results for speech transmission index (STI) and U50 values show that classrooms having U50 values greater than +4.1 dB correspond to STI values of 0.60, indicating ‘Good’ acoustical conditions for speech intelligibility. The U50 value is 0.9 dB lower than that of the previous study made in quietly occupied classrooms without student activities. The present result indicates that the noise level is not the same as experienced during actual lecturing situations in university classrooms. When the classroom has a SNR (125-4k) value of 7.7 dB or lower a C50 (125-4k) value of 7.3 dB or greater to be required for achieving good acoustical conditions during lectures in university classrooms.

키워드